research article the multiple effects of precursors on the...

Hindawi Publishing CorporationInternational Journal of PhotoenergyVolume 2013 Article ID 685038 9 pageshttpdxdoiorg1011552013685038

Research ArticleThe Multiple Effects of Precursors on the Properties ofPolymeric Carbon Nitride

Wendong Zhang1 Qin Zhang1 Fan Dong2 and Zaiwang Zhao2

1 College of Urban Construction and Environmental EngineeringChongqing University Chongqing 400045 China

2 Chongqing Key Laboratory of Catalysis and Functional Organic Molecules College of Environmental and Biological EngineeringChongqing Technology and Business University Chongqing 400067 China

Correspondence should be addressed to Fan Dong dfctbu126com

Received 21 May 2013 Accepted 18 July 2013

Academic Editor Pengyi Zhang

Copyright copy 2013 Wendong Zhang et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

Polymeric graphitic carbon nitride (g-C3N4) materials were prepared by direct pyrolysis of thiourea dicyandiamide melamine

and urea under the same conditions respectively In order to investigate the effects of precursors on the intrinsic physicochemicalproperties of g-C

3N4 a variety of characterization tools were employed to analyze the samples The photocatalytic activity of the

sampleswas evaluated by the removal ofNO in gas phase under visible light irradiationThe results showed that the as-preparedCN-T (from thiourea) CN-D (from dicyandiamide) CN-M (from melamine) and CN-U (from urea) exhibited significantly differentmorphologies andmicrostructuresThe band gaps of CN-T CN-D CN-M andCN-Uwere 251 258 256 and 288 eV respectivelyBoth thermal stability and yield are in the following order CN-MgtCN-DgtCN-TgtCN-U The photoactivity of CN-U (319) ishigher than that of CN-T (296) CN-D (222) and CN-M (268) Considering the cost toxicity and yield of the precursorsand the properties of g-C

3N4 the best precursor for preparation of g-C

3N4was melamine The present work could provide new

insights into the selection of suitable precursor for g-C3N4synthesis and in-depth understanding of the microstructure-dependent

photocatalytic activity of g-C3N4

1 Introduction

Visible-light-active photocatalysts are attracting increasinginterests for their potential application in the areas of envi-ronmental protection material science and solar energyconversion by directly utilizing nature sunlight and artificialindoor illumination [1ndash3] During the past few decadesmanyefforts have been devoted to develop novel and efficientvisible light photocatalytic systems including inorganic pho-tocataylsts (eg Fe

2O3 (BiO)

2CO3 Cu2SnS3 SrTiO

3 and

WO3BiOCl) [4ndash7] organic photocataylsts (eg graphitic

carbon nitride g-C3N4) and elemental photocataylsts (eg

Si P S and Se) [8ndash10]In particular g-C

3N4material as a novel mental-free

organic photocatalyst has triggered great attention in the fun-damental and applied scientific researches due to its suitableelectronic band structure nontoxic nature biocompatibility

high thermal and chemical stability easily available at lowcost and amenability to chemical modification [11ndash16] Prop-ertiesmentioned previouslymake it a promising organic pho-tocatalyst for solar energy converting organic photosynthe-sis drug delivery and environment remediation under visiblelight irradiation [17ndash19]

g-C3N4can be prepared by the direct pyrolysis of vari-

ous organic precursors Dong et al prepared g-C3N4from

thiourea and urea at 550∘C for 2 h [20 21] respectively Yan etal obtained g-C

3N4from melamine at 550∘C for 4 h [22] Xu

et al prepared g-C3N4by directly heating dicyandiamide first

at 350∘C for 2 h and then 550∘C for another 2 h [23] respec-tivelyThe different pyrolysis conditions for g-C

3N4synthesis

made the comparison of the precursors difficult Until nowlittle information is known about the effects of precursorson intrinsic physicochemical properties of g-C

3N4under the

same pyrolysis conditions including morphology band gap

2 International Journal of Photoenergy

Table 1 The cost acute toxicity and melting point of thioureadicyandiamide melamine and urea [16]

Precursors Cost ($t) Acute toxicityLD50 (oral rat)

Melting point(∘C)

Thiourea 3906 125mgkg 182Dicyandiamide 1538 4000mgkg 209Melamine 2025 3248mgkg 345Urea 450 8500mgkg 133

thermal stability surface area pore volume and yield andvisible light photocatalytic activity It is thus highly desirableto solve this issue in order to screen the most suitable pre-cursors for synthesis of g-C

3N4

In this paper g-C3N4materials were prepared by directly

treating thiourea dicyandiamide melamine and urea underthe same condition (550∘C for 3 h in air) respectively Theprecursors are easily available in the chemical industry at lowcost (see Table 1) Various characterization tools were utilizedto analyze the effects of precursors on the intrinsic physic-ochemical properties and photocatalytic activity of g-C

3N4

The results showed that the precursors had significant effecton the properties of g-C

3N4 Considering the cost toxicity

and yield of the precursors and the properties of g-C3N4 the

best precursor was confirmed

2 Experimental

21 Synthesis of g-C3N4 In a typical synthesis 12 g of thiourea

was put into a semiclosed alumina crucible with a cover andthen heated to 550∘C in a muffle furnace for 3 h at a heatingrate of 10∘Cminminus1 Following the same procedure g-C

3N4

samples were prepared by directly treating dicyandiamidemelamine and urea respectively After the reaction the alu-mina crucible was cooled to room temperatureThe resultantg-C3N4were collected and ground into powder respectively

The different g-C3N4prepared from thiourea dicyandi-

amidemelamine and ureawere labeled as CN-T CN-D CN-M and CN-U respectively

22 Characterization The crystal phases of the sampleswere analyzed by X-ray diffraction with Cu K120572 radiation(XRD model Dmax RA Rigaku Co Japan) FT-IR spectrawere recorded on a Nicolet Nexus spectrometer on samplesembedded in KBr pellets The morphology and structure ofthe samples were further examined by transmission electronmicroscopy (TEM JEM-2010 Japan) The UV-vis diffusereflection spectra were obtained for the dry-pressed disksamples using a Scan UV-vis spectrophotometer (UV-visDRS UV-2450 Shimadzu Japan) equipped with an integrat-ing sphere assembly using BaSO

4as the reflectance sample

Nitrogen adsorption-desorption was conducted on a nitro-gen adsorption apparatus (ASAP 2020 USA) The thermalstability was detected by using thermogravimetry analysis(TG-DSC Netsch STA 449F3) under N

2gas atmosphere All

the samples were degassed at 150∘C prior to measurements

23 Visible Light Photocatalytic Performance The photocat-alytic activity was investigated by removal of NO at ppb levelsin a continuous flow reactor at ambient temperature Thevolume of the rectangular reactor which was made of poly-methyl methacrylate plastics and covered with quartz-glasswas 45 L (30 cmtimes 15 cmtimes 10 cm) A 100W commercial tung-sten halogen lamp (General Electric) was vertically placedoutside and above the reactor Four minifans were used tocool the flow system Adequate distance was also kept fromthe lamp to the reactor for the same purpose to keep thetemperature at a constant level For the visible light photo-catalytic activity test experiment a UV cut-off filter (420 nm)was adopted to remove UV light in the light beam

For each photocatalytic activity test two sample dishes(with a diameter of 120 cm) containing photocatalyst powderwere placed in the center of the reactorTheweight of the pho-tocatalyst used for each dish was kept at 01 g g-C

3N4sample

was added into 30mL of H2O and sonicated for 10min

and then photocatalyst samples were prepared by coatingaqueous suspension of the samples onto the glass dishes Thecoated dishwas pretreated at 60∘C to removewater in the sus-pension and then cooled to room temperature before photo-catalytic testing

TheNO gas was acquired from a compressed gas cylinderat a concentration of 100 ppm of NO (N

2balance BOC

gas) with the National Institute of Standards and Technology(NIST) standardThe initial concentration of NOwas dilutedto about 600 ppb by the air stream supplied by a zero air gen-erator (Thermo Environmental Inc model 111) The relativehumidity at indoor environmental condition is 40ndash80The desired relative humidity in the present system is con-trolled at 50 in the gas flowwhich could simulate the indoorenvironmental conditions The desired relative humidity(RH) level of the NO flow was controlled at 50 by passingthe zero air streams through a humidification chamber Thegas streams were premixed completely by a gas blender andthe flow rate was controlled at 24 Lminminus1 by a mass flowcontroller After the adsorption-desorption equilibrium wasachieved the lamp was turned on The concentration of NOwas continuously measured by a chemiluminescence NOanalyzer (Thermo Environmental Instruments Inc model42c) which monitors NO NO

2 and NOx (NOx represents

NO + NO2) with a sampling rate of 07 Lminminus1 The removal

ratio (120578) of NO was calculated as 120578 () = (1 minus 1198621198620) times 100

where 119862 and 1198620are concentrations of NO in the outlet steam

and the feeding stream respectively The kinetics of photo-catalytic NO removal reaction is a pseudofirst order reactionat low NO concentration as ln(119862

0119862) = 119896119905 where 119896 is the

apparent rate constant

3 Result and Discussion

TheXRD patterns (Figure 1(a)) of the samples prepared fromthiourea dicyandiamide melamine and urea can be indexedto g-C

3N4[24ndash26] The strongest interplanar stacking peaks

of the conjugated aromatic systems at around 276∘ areindexed to graphitic materials as the (002) peak The smallangle peaks at around 130∘ can be indexed to (100) peak

International Journal of Photoenergy 3

5 10 15 20 25 30 35 40

CN-U

CN-M

CN-D

CN-T

Inte

nsity

(au

)

2120579 (deg)

(a)

25 26 27 28 29 30

CN-U

CN-M

CN-D

CN-T

Inte

nsity

(au

)

2120579 (deg)

(b)

Figure 1 XRD patterns of the CN-T CN-D CN-M and CN-U (a) and enlarged view of the (002) peak (b)

400 600 800 1000 1200 1400 1600 1800 2000

CN-U

CN-M

CN-D

CN-T

Tran

smitt

ance

(au

)

Wavenumber (cmminus1)

(a)

2000 2500 3000 3500 4000

CN-U

CN-M

CN-D

CN-T

Tran

smitt

ance

(au

)


(b)

Figure 2 FT-IR spectra for CN-T CN-D CN-M and CN-U

of graphitic materials corresponding to the in-plane tri-s-triazine units which formed one-dimensional (1D) melonstrands Further observation implies (Figure 1(b)) that thetypical (002) peak is 2743∘ for CN-T 2747∘ for CN-D 2760∘for CN-M and 2772∘ for CN-U respectively indicating thatthe interplanar distance tends to decrease and g-C

3N4struc-

ture becomes more compact The dense structure can beascribed to the localization of the electrons and stronger bind-ing between the layers [27 28] The dominant (002) diffrac-tion peaks shifted toward higher diffraction angles for CN-Ucompared with CN-T indicating that O-containing precur-sors (urea) could improve the polycondensation of g-C

3N4 In

addition the intensity and breadth of the XRD patterns(Figure 1) are different due to the presence of different nano-structures and morphologies of the as-prepared g-C

3N4[29]

The chemical structures of dicyandiamide and melaminecontaina C=N bond which plays a key role in the formationof g-C

3N4 However both the S-containing thiourea and

O-containing urea do not containa C=N bond The factindicates that the formation mechanisms and condensationdegrees of thiourea and urea are different from that of dicyan-diamide and melamine [20ndash22 30]

Figure 2(a) shows that the weak absorption at the 700ndash800 cmminus1 region is assigned to the bending vibrationmode ofCN heterocycles and the characteristic out of plane bendingvibration mode of the triazine units at 810 cmminus1 for all thesamples [31] All the samples reveal several bands in the 1200ndash1650 cmminus1 region which corresponds to the typical stretchingvibration modes of the heptazine heterocyclic ring (C

6N7)

units [32]The stretching vibration modes of NndashH and OndashH at

3000ndash3500 cmminus1 are also observed (Figure 2(b)) indicatingthe existence of uncondensed amino groups and absorbedH2Omolecules in all the samples [33] It can be seen that the

peak intensity of CN-U at 400ndash4000 cmminus1 is stronger thanthat ofCN-TCN-D andCN-M indicating thatO-containing


(a) (b)

(c) (d)

Figure 3 TEM images of CN-T (a) CN-D (b) CN-M (c) and CN-U (d)

precursors could improve the polycondensation of g-C3N4

[34]The morphologies and microstructures of CN-T CN-D

CN-M and CN-U were observed by TEM As shown inFigure 3 all the samples consist of large amounts of packinglayers with different sizes of nanosheets and nanoparti-cles which exhibit obviously wrinkles and irregular shapesFigure 3(a) shows that CN-T is composed of smooth and flatlayers Numerous large buckle nanosheets with aggregatedstructures which formed smooth layers in the CN-D sam-ple can be seen in Figure 3(b) By observing carefully forCN-M (Figure 3(c)) the layers consist of dense and thicknanosheets with irregular shape Figure 3(d) shows that CN-U is composed of smooth and thin layers with typical porousmorphology and loose structureThe result clearly shows thatCN-U prepared from urea favors the formation of typicalporous structure The fact indicates that the morphologiesand microstructures of the resultant g-C

3N4strongly depend

on the different heteroatom-containing precursorsAs shown in Figure 4(a) all the samples exhibit excellent

visible light absorption and the absorption edges of the sam-ples shift apparently to longer wavelengths from CN-U toCN-T The band energies (119864

119892) which can be estimated from

the intercept of the tangents to the plots of (119860ℎ])12 versusphoto energy (Figure 4(b)) are 251 258 256 and 288 eVfor CN-T CN-D CN-M and CN-U respectively The factindicates that the precursors could affect the band gap and

absorption edge of g-C3N4 which may be caused by the dif-

ferent local structures defects and degrees of condensationduring the pyrolysis [8 11]

Figure 5 shows the nitrogen adsorption-desorptionisotherms and corresponding curves of the pore sizedistribution for CN-T CN-D CN-M and CN-U Theisotherms of CN-T (Figure 5(a)) CN-D (Figure 5(c)) andCN-M (Figure 5(e)) can be classified to type IV whichindicates the presence of mesoporesThe CN-U exhibits typeIII behavior (Figure 5(g)) which can be ascribed to the weakadsorbent-adsorbent interaction [35] The specific surfaceareas and pore volumes of CN-T (23m2g and 014 cm3g)and CN-U (153m2g and 040 cm3g) are significantlyhigher than that of CN-D (18m2g and 009 cm3g) andCN-M (14m2g and 006 cm3g) The data illustrates thatthe heteroatoms of sulfur and oxygen play a key role inincreasing the specific surface area and enlarging the porevolume during the condensation The formation of H

2S and

CO2 release of NH

3 and generation of additional H

2Ovapor

during the pyrolysis of thiourea and urea favor the expansionof the packing layers and porous structure [32 35] Furtherobservation implies that all the samples have microporesand mesopores The interconnected porous network couldmainly contribute to the formation of micropores andmesopores of CN-T (Figure 5(b)) and CN-U (Figure 5(h))the aggregation of nanosheets and nanoparticles could resultin the formation of the micropores and mesopores of CN-D(Figure 5(d)) and CN-M (Figure 5(f)) [19 20]


300 350 400 450 500 550 600 650Wavelength (nm)

Abs (

au)

CN-U

CN-MCN-D

CN-T

(a)

(Ahv

)12

Band gap (eV)22 24 26 28 3 32 34

CN-U

CN-M

CN-D

CN-T

CN-TEg = 251 eVCN-D Eg = 258 eVCN-M Eg = 256 eVCN-U Eg = 288 eV

(b)

Figure 4 UV-vis DRS (a) and plots of (119860ℎ])12 versus photo energy (b) of CN-T CN-D CN-M and CN-U

Table 2 The 119878BET pore volume band gap removal ration initial rate constant 119896 yield and thermal stability of CN-T CN-D CN-M andCN-U

Samples 119878BET (m2g) Pore volume

(cm3g) Band gap (eV) Removal ratio120578 () k (minminus1) Yield (g) Thermal

stability (∘C)CN-T 23 014 251 296 0310 146 lt550∘CCN-D 18 009 258 222 0079 373 lt563∘CCN-M 14 006 256 268 0298 532 lt575∘CCN-U 153 040 288 319 0384 012 lt530∘C

In order to understand the thermal stability of CN-T CN-D CN-M and CN-U the thermal analysis was carried outby using TG-DSC and the heating rate of 20∘Cmin under N

2

gas atmosphere It can be found that the CN-T (Figure 6(a))CN-D (Figure 6(b)) and CN-M (Figure 6(c)) became unsta-ble when the heating temperature was above 550 563 and575∘C respectively The exothermic peaks can be seen at6724 for CN-T 6831 for CN-D and 6495∘C for CN-Uwhich should be attributed to the decomposition for thesamples Figure 6(d) shows that no significant weight loss ofCN-U is recorded when the temperature is below 530∘C andcomplete decomposition of CN-U occurred at 750∘C Furtherobservation reveals that there are two strong exothermicpeaks at 5501 and 6824∘C of CN-U which can be ascribedto the sublimation and thermal decomposition [36] respec-tively It should be noted that the thermal stability of the sam-ples is different due to the different degrees of condensationand the packing between the layers during the polymerization[37 38]

The photocatalytic performance of the as-prepared sam-ples was further evaluated by removal of NO in gas phasein order to demonstrate their potential ability for indoor airpurification under visible light irradiation at room temper-ature (Figure 7) There are four reactions of the photocat-alytic materials which involved that NO reacted with the

photo-generated reactive radicals and produced HNO2and

HNO3displayed in the following [39]

NO + 2∙OH 997888rarr NO2+H2O

NO2+∙OH 997888rarr NO

3

minus+H+

NO +NO2+H2O 997888rarr 2HNO

2

NO+ ∙O2

minus997888rarr NO

3

minus

(1)

Figure 7(a) shows the variation of NO concentration(1198621198620) with irradiation time over the samples under

visible light irradiation (120582 gt 420 nm) Here 1198620is the initial

concentration of NO and 119862 is the concentration of NO afterphotocatalytic reaction for time 119905

As shown in Figure 7(a) the concentration of NO forall samples decreased rapidly due to the photocatalyticdegradation in 5min However the reaction intermediatesand final products generated during irradiation may occupythe active sites of photocatalyst which result in the decreasein activity After 40min irradiation the removal rates andapparent rate constants of CN-T (292 and 0310minminus1)and CN-U (322 and 0384minminus1) are higher than thatof CN-D (222 and 0079minminus1) and CN-M (262 and


20

40

60

80

100

0 02 04 06 08 1Relative pressure (PP0)

Adso

rbed

vol

ume (

cm3g

)

(a)

1 10 100

0

100

200

300

400

500

600

Pore diameter (nm)

dVdD

(cm

3gminus

1)times

105

(b)

10

20

30

40

50

60


Adso

rbed

vol

ume (

cm3g

)

(c)

0

50

100

150

200

250

1 10 100Pore diameter (nm)

dVdD

(cm

3gminus

1)times

105

(d)

10

20

30

40


Adso

rbed

vol

ume (

cm3g

)

(e)

02468

101214

1 10Pore diameter (nm)

dVdD

(cm

3gminus

1)times

105

(f)

50

100

150

200

250


Adso

rbed

vol

ume (

cm3g

)

(g)

0

100

200

300

400

500

600


dVdD

(cm

3gminus

1)times

105

(h)

Figure 5 N2adsorption-desorption isotherms of CN-T (a) CN-D (c) CN-M (e) and CN-U (g) and the corresponding pore size distribution

curves of CN-T (b) CN-D (d) CN-M (f) and CN-U (h)


0 100 200 300 400 500 600 700 800 900 1000

0

20

40

60

80

100 02

exo

Wei

ght l

oss (

)

minus2minus4minus6minus8minus10minus12minus14minus16minus18minus20minus22minus24minus26minus28

DSC

(m

Wm

g)

Temperature (∘C)

6724 ∘C

9862

(a)

0 100 200 300 400 500 600 700 800 900 1000

0

20

40

60

80

100

0

2

4

exo

Wei

ght l

oss (

)

minus2

minus4

minus6

minus8

minus10

minus12

DSC

(m

Wm

g)

Temperature (∘C)

6831 ∘C

9554

(b)

0 100 200 300 400 500 600 700 800 900 1000

0

20

40

60

80

100exo

Wei

ght l

oss (

)

0minus2

minus4

minus6

minus8

minus10

minus12

minus14

minus16

minus18

minus20

DSC

(m

Wm

g)

Temperature (∘C)

6495 ∘C

9547

(c)

exo

100 200 300 400 500 600 700 800 900 1000

0

20

40

60

80

100

Wei

ght l

oss (

)

0

minus10

minus20

minus30

minus40

DSC

(m

Wm

g)

Temperature (∘C)

6824 ∘C

5501 ∘C

7769

1407

824

(d)

Figure 6 TG-DSC thermalgrams for CN-T (a) CN-D (b) CN-M (c) and CN-U (d)

50

60

70

80

90

100

0 10 20 30 40Time (min)

CC

0(

)

CN-UCN-MCN-D CN-T

(a)

04

035

03

025

02

015

01

005

0

k(m

inminus1)

SamplesCN-UCN-MCN-D CN-T

(b)

Figure 7 Photocatalytic activity (a) and initial rate constants (b) of CN-T CN-D CN-M and CN-U for removal of NO under visible lightirradiation (120582 gt 420 nm) at room temperature


0298minminus1) respectively Generally CN-T CN-D and CN-M with narrower band gaps than CN-U (see Table 2) arefavorable for photocatalytic reaction due to the enhancedvisible light absorption with more available photogeneratedelectron hole In fact the high surface areas and largepore volumes can enhance the adsorption of reactantsand diffusion of the reaction products and provide moreefficient active sites for photochemical reaction [40 41]Thus the surface area and pore volume of CN-U play amore significant role in NO degradation than the electronicproperties However it is interesting to find that the CN-M exhibits higher photocatalytic activity than that of CN-D Figure 4(b) shows that the band energy of CN-M isnarrower than that of CN-D which can enhance visiblelight absorption in CN-M sample On the other hand theenhanced condensation of CN-M can effectively reduce thenumber of structure defects (eg uncondensation groups of ndashNH2and ndashNH)which always capture the electrons or holes to

prevent the following photoredox reaction [8] The fact indi-cates that the photocatalytic efficiency strongly depends onthe surface area pore volume band energy and the degree ofcondensation of g-C

3N4

To ensure the large-scale application four evaluationindicators were proposed for screening the most suitableprecursors including the cost toxicity and yield of the pre-cursors and the removal rate for the contaminant As shownin Tables 1 and 2 melamine exhibits the middle cost toxicityand removal ratio for the degradation of NO However itpossesses the highest yield among the four precursors Basedon the advantages analysis previously mentioned the bestprecursor is melamine

4 Conclusions

In summary g-C3N4samples were prepared by a simple

pyrolysis of thiourea dicyandiamide melamine and ureaunder the same procedures respectively The systematic re-search results confirmed that the precursors have significanteffect on the morphology band gap surface area pore vol-ume thermal stability and visible light photocatalytic activityof g-C

3N4 Considering the cost toxicity and yield of the

precursors and the properties of g-C3N4 the best precursor

for preparation of g-C3N4is melamine The present work

could provide new insights into appropriate selection ofprecursors for g-C

3N4synthesis as visible light photocatalyst

in environmental protection

Conflict of Interests

The authors declare that they have no conflict of interests

Acknowledgments

This research is financially supported by the National Nat-ural Science Foundation of China (51108487) the NationalHigh Technology Research and Development Program (863Program) of China (2010AA064905) the Natural ScienceFoundation Project of CQ CSTC (cstc2012jjA20014) and the

Critical Patented Projects in the Control and Management ofthe National Polluted Water Bodies (2012ZX07102-001-003)

References

[1] J S Zhang J H Sun K Maeda et al ldquoSulfur-mediated syn-thesis of carbon nitride band-gap engineering and improvedfunctions for photocatalysisrdquo Energy amp Environmental Sciencevol 4 no 3 pp 675ndash678 2011

[2] H Tong S X Ouyang Y P Bi N T Umezawa M Oshikiriand J H Ye ldquoNano-photocatalytic materials possibilities andchallengesrdquoAdvancedMaterials vol 24 no 2 pp 229ndash251 2012

[3] J G Yu M Jaroniec and G X Lu ldquoTiO2photocatalytic mate-

rialsrdquo International Journal of Photoenergy vol 2012 Article ID206183 5 pages 2012

[4] N Todorova T Giannakopoulou G Romanos T Vaimakis JG Yu and C Trapalis ldquoPreparation of fluorine-doped TiO

2

photocatalysts with controlled crystalline structurerdquo Interna-tional Journal of Photoenergy vol 2008 Article ID 534038 9pages 2008

[5] F Dong W K Ho S C Lee et al ldquoTemplate-free fabricationand growth mechanism of uniform (BiO)

2CO3hierarchical

hollow microspheres with outstanding photocatalytic activitiesunder both UV and visible light irradiationrdquo Journal of Materi-als Chemistry vol 21 no 33 pp 12428ndash12436 2011

[6] J G Yu P Y Zhang H G Yu and C Trapalis ldquoEnvironmentalphotocatalysisrdquo International Journal of Photoenergy vol 2012Article ID 594214 4 pages 2012

[7] Q Y Chen andDMa ldquoPreparation of nanostructured Cu2SnS3

photocatalysts by solvothermal methodrdquo International Journalof Photoenergy vol 2013 Article ID 593420 5 pages 2013

[8] X CWang S Blechert andMAntonietti ldquoPolymeric graphiticcarbonnitride for heterogeneous photocatalysisrdquoACSCatalysisvol 2 no 8 pp 1596ndash1606 2012

[9] Y J Cui Z X Ding X Z Fu and X CWang ldquoConstruction ofconjugated carbon nitride nanoarchitectures in solution at lowtemperatures for photoredox catalysisrdquo Angewandte Chemievol 51 no 47 pp 11814ndash11818 2012

[10] G Liu P Niu and HM Cheng ldquoVisible-light-active elementalphotocatalystsrdquo ChemPhysChem vol 14 no 5 pp 885ndash8922013

[11] Y Wang X C Wang and M Antonietti ldquoPolymeric graphiticcarbon nitride as a heterogeneous organocatalyst from photo-chemistry to multipurpose catalysis to sustainable chemistryrdquoAngewandte Chemie vol 51 no 1 pp 68ndash89 2012

[12] Z Z Lin and X CWang ldquoNanostructure engineering and dop-ing of conjugated carbon nitride semiconductors for hydrogenphotosynthesisrdquo Angewandte Chemie vol 52 no 6 pp 1735ndash1738 2013

[13] GXin andY LMeng ldquoPyrolysis synthesized g-C3N4for photo-

catalytic degradation of methylene bluerdquo Journal of Chemistryvol 2013 Article ID 187912 5 pages 2013

[14] J D Hong X Y Xia Y S Wang and R Xu ldquoMesoporouscarbon nitride with in situ sulfur doping for enhanced pho-tocatalytic hydrogen evolution from water under visible lightrdquoJournal of Materials Chemistry vol 22 no 30 pp 15006ndash150122012

[15] G P Mane D S Dhawale C Anand et al ldquoSelective sensingperformance of mesoporous carbon nitride with a highly or-dered porous structure prepared from 3-amino-124-triazinerdquoJournal of Materials Chemistry A vol 1 no 8 pp 2913ndash29202013


[16] httpenwikipediaorgwikiMainPage[17] X H Li X C Wang and M Antonietti ldquoMesoporous g-

C3N4nanorods as multifunctional supports of ultrafine metal

nanoparticles hydrogen generation from water and reductionof nitrophenol with tandem catalysis in one steprdquo ChemicalScience vol 3 no 6 pp 2170ndash2174 2012

[18] B Kiskan J S Zhang X C Wang M Antonietti and Y YagcildquoMesoporous graphitic carbon nitride as a heterogeneous visi-ble light photoinitiator for radical polymerizationrdquo ACS MacroLetters vol 1 no 5 pp 546ndash549 2012

[19] M Shalom S Inal C Fettkenhauer D Neher and M Antoni-etti ldquoImproving carbon nitride photocatalysis by supramolec-ular preorganization of monomersrdquo Journal of the AmericanChemical Society vol 135 no 19 pp 7118ndash7121 2013

[20] F Dong LWWu Y J SunM Fu Z BWu and S C Lee ldquoEffi-cient synthesis of polymeric g-C

3N4layered materials as novel

efficient visible light driven photocatalystsrdquo Journal of MaterialsChemistry vol 21 no 39 pp 15171ndash15174 2011

[21] F Dong Y J Sun L WWu M Fu and Z B Wu ldquoFacile trans-formation of low cost thiourea into nitrogen-rich graphitic car-bon nitride nanocatalyst with high visible light photocatalyticperformancerdquo Catalysis Science amp Technology vol 2 no 7 pp1332ndash1335 2012

[22] S C Yan Z S Li and Z G Zou ldquoPhotodegradation perfor-mance of g-C

3N4fabricated by directly heating melaminerdquo

Langmuir vol 25 no 17 pp 10397ndash10401 2009[23] H Xu J Yan Y G Xu et al ldquoNovel visible-light-driven

AgXgraphite-like C3N4(X =Br I) hybrid materials with syn-

ergistic photocatalytic activityrdquo Applied Catalysis B vol 129 pp182ndash193 2013

[24] A Vinu ldquoTwo-dimensional hexagonally-ordered mesoporouscarbon nitrides with tunable pore diameter surface area andnitrogen contentrdquo Advanced Functional Materials vol 18 no5 pp 816ndash827 2008

[25] A Vinu K Ariga T Mori et al ldquoPreparation and characteri-zation of well-ordered hexagonal mesoporous carbon nitriderdquoAdvanced Materials vol 17 no 13 pp 1648ndash1652 2005

[26] A Vinu P Srinivasu D P Sawant et al ldquoThree-dimensionalcage typemesoporousCN-based hybridmaterial with very highsurface area and pore volumerdquo Chemistry of Materials vol 19no 17 pp 4367ndash4372 2007

[27] X G Ma Y H Lv J Xu Y F Liu R Q Zhang and Y F Zhu ldquoAstrategy of enhancing the photoactivity of g-C

3N4via doping

of nonmetal elements a first-principles studyrdquo The Journal ofPhysical Chemistry C vol 116 no 44 pp 23485ndash23493 2012

[28] J Gracia and P Kroll ldquoFirst principles study of C3N4carbon

nitride nanotubesrdquo Journal of Materials Chemistry vol 19 no19 pp 3020ndash3026 2009

[29] F Goettmann A Fischer M Antonietti and A ThomasldquoChemical synthesis of mesoporous carbon nitrides using hardtemplates and their use as ametal-free catalyst for Friedel-Craftsreaction of benzenerdquo Angewandte Chemie vol 45 no 27 pp4467ndash4471 2006

[30] Y Zhang Z M Pan and X C Wang ldquoAdvances in photocatal-ysis in Chinardquo Chinese Journal of Catalysis vol 34 no 3 pp524ndash535 2013

[31] V N Khabashesku J L Zimmerman and J L MargraveldquoPowder synthesis and characterization of amorphous carbonnitriderdquo Chemistry of Materials vol 12 no 11 pp 3264ndash32702000

[32] G G Zhang J S Zhang M W Zhang and X C Wang ldquoPoly-condensation of thiourea into carbon nitride semiconductors asvisible light photocatalystsrdquo Journal of Materials Chemistry vol22 no 16 pp 8083ndash8091 2012

[33] Y Ham K Maeda D Cha K Takanabe and K DomenldquoSynthesis and photocatalytic activity of poly (triazine imide)rdquoChemistry vol 8 no 1 pp 218ndash224 2013

[34] Y J Cui J S Zhang G G Zhang et al ldquoSynthesis of bulkand nanoporous carbon nitride polymers from ammoniumthiocyanate for photocatalytic hydrogen evolutionrdquo Journal ofMaterials Chemistry vol 21 no 34 pp 13032ndash13039 2011

[35] Y W Zhang J H Liu G Wu and W Chen ldquoPorous graphiticcarbon nitride synthesized via direct polymerization of urea forefficient sunlight-driven photocatalytic hydrogen productionrdquoNanoscale vol 4 no 17 pp 5300ndash5303 2012

[36] S Wang Q Y Gao and J C Wang ldquoThermodynamic analysisof decomposition of thiourea and thiourea oxidesrdquoThe Journalof Physical Chemistry B vol 109 no 36 pp 17281ndash17289 2005

[37] J Xu H T Wu X Wang B Xue Y X Li and Y Cao ldquoAnew and environmentally benign precursor for the synthesisof mesoporous g-C

3N4with tunable surface areardquo Physical

Chemistry Chemical Physics vol 15 no 13 pp 4510ndash4517 2013[38] M Sadhukhan and S Barman ldquoBottom-up fabrication of two-

dimensional carbon nitride and highly sensitive electrochemi-cal sensors for mercuric ionsrdquo Journal of Materials Chemistry Avol 1 no 8 pp 2752ndash2756 2013

[39] H T Tian J W Li M Ge Y P Zhao and L Liu ldquoRemoval ofbisphenol a by mesoporous BiOBr under simulated solar lightirradiationrdquo Catalysis Science amp Technology vol 2 no 11 pp2351ndash2355 2012

[40] J S Zhang X F Chen K Takanabe et al ldquoSynthesis of a carbonnitride structure for visible-light catalysis by copolymerizationrdquoAngewandte Chemie vol 49 no 2 pp 441ndash444 2010

[41] J H Li B Shen Z H Hong B Z Lin B F Gao and YL Chen ldquoA facile approach to synthesize novel oxygen-dopedg-C3N4with superior visible-light photoreactivityrdquo Chemical

Communications vol 48 no 98 pp 12017ndash12019 2012

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Inorganic ChemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

International Journal ofPhotoenergy


Carbohydrate Chemistry

International Journal of


Journal of

Chemistry


Advances in

Physical Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

SpectroscopyInternational Journal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of


Chromatography Research International


Applied ChemistryJournal of



Theoretical ChemistryJournal of


Journal of

Spectroscopy

Analytical ChemistryInternational Journal of


Journal of


Quantum Chemistry


Organic Chemistry International

ElectrochemistryInternational Journal of



CatalystsJournal of


Table 1 The cost acute toxicity and melting point of thioureadicyandiamide melamine and urea [16]

Precursors Cost ($t) Acute toxicityLD50 (oral rat)

Melting point(∘C)

Thiourea 3906 125mgkg 182Dicyandiamide 1538 4000mgkg 209Melamine 2025 3248mgkg 345Urea 450 8500mgkg 133

thermal stability surface area pore volume and yield andvisible light photocatalytic activity It is thus highly desirableto solve this issue in order to screen the most suitable pre-cursors for synthesis of g-C

3N4

In this paper g-C3N4materials were prepared by directly

treating thiourea dicyandiamide melamine and urea underthe same condition (550∘C for 3 h in air) respectively Theprecursors are easily available in the chemical industry at lowcost (see Table 1) Various characterization tools were utilizedto analyze the effects of precursors on the intrinsic physic-ochemical properties and photocatalytic activity of g-C

3N4

The results showed that the precursors had significant effecton the properties of g-C

3N4 Considering the cost toxicity

and yield of the precursors and the properties of g-C3N4 the

best precursor was confirmed

2 Experimental

21 Synthesis of g-C3N4 In a typical synthesis 12 g of thiourea

was put into a semiclosed alumina crucible with a cover andthen heated to 550∘C in a muffle furnace for 3 h at a heatingrate of 10∘Cminminus1 Following the same procedure g-C

3N4

samples were prepared by directly treating dicyandiamidemelamine and urea respectively After the reaction the alu-mina crucible was cooled to room temperatureThe resultantg-C3N4were collected and ground into powder respectively

The different g-C3N4prepared from thiourea dicyandi-

amidemelamine and ureawere labeled as CN-T CN-D CN-M and CN-U respectively

22 Characterization The crystal phases of the sampleswere analyzed by X-ray diffraction with Cu K120572 radiation(XRD model Dmax RA Rigaku Co Japan) FT-IR spectrawere recorded on a Nicolet Nexus spectrometer on samplesembedded in KBr pellets The morphology and structure ofthe samples were further examined by transmission electronmicroscopy (TEM JEM-2010 Japan) The UV-vis diffusereflection spectra were obtained for the dry-pressed disksamples using a Scan UV-vis spectrophotometer (UV-visDRS UV-2450 Shimadzu Japan) equipped with an integrat-ing sphere assembly using BaSO

4as the reflectance sample

Nitrogen adsorption-desorption was conducted on a nitro-gen adsorption apparatus (ASAP 2020 USA) The thermalstability was detected by using thermogravimetry analysis(TG-DSC Netsch STA 449F3) under N

2gas atmosphere All

the samples were degassed at 150∘C prior to measurements

23 Visible Light Photocatalytic Performance The photocat-alytic activity was investigated by removal of NO at ppb levelsin a continuous flow reactor at ambient temperature Thevolume of the rectangular reactor which was made of poly-methyl methacrylate plastics and covered with quartz-glasswas 45 L (30 cmtimes 15 cmtimes 10 cm) A 100W commercial tung-sten halogen lamp (General Electric) was vertically placedoutside and above the reactor Four minifans were used tocool the flow system Adequate distance was also kept fromthe lamp to the reactor for the same purpose to keep thetemperature at a constant level For the visible light photo-catalytic activity test experiment a UV cut-off filter (420 nm)was adopted to remove UV light in the light beam

For each photocatalytic activity test two sample dishes(with a diameter of 120 cm) containing photocatalyst powderwere placed in the center of the reactorTheweight of the pho-tocatalyst used for each dish was kept at 01 g g-C

3N4sample

was added into 30mL of H2O and sonicated for 10min

and then photocatalyst samples were prepared by coatingaqueous suspension of the samples onto the glass dishes Thecoated dishwas pretreated at 60∘C to removewater in the sus-pension and then cooled to room temperature before photo-catalytic testing

TheNO gas was acquired from a compressed gas cylinderat a concentration of 100 ppm of NO (N

2balance BOC

gas) with the National Institute of Standards and Technology(NIST) standardThe initial concentration of NOwas dilutedto about 600 ppb by the air stream supplied by a zero air gen-erator (Thermo Environmental Inc model 111) The relativehumidity at indoor environmental condition is 40ndash80The desired relative humidity in the present system is con-trolled at 50 in the gas flowwhich could simulate the indoorenvironmental conditions The desired relative humidity(RH) level of the NO flow was controlled at 50 by passingthe zero air streams through a humidification chamber Thegas streams were premixed completely by a gas blender andthe flow rate was controlled at 24 Lminminus1 by a mass flowcontroller After the adsorption-desorption equilibrium wasachieved the lamp was turned on The concentration of NOwas continuously measured by a chemiluminescence NOanalyzer (Thermo Environmental Instruments Inc model42c) which monitors NO NO

2 and NOx (NOx represents

NO + NO2) with a sampling rate of 07 Lminminus1 The removal

ratio (120578) of NO was calculated as 120578 () = (1 minus 1198621198620) times 100

where 119862 and 1198620are concentrations of NO in the outlet steam

and the feeding stream respectively The kinetics of photo-catalytic NO removal reaction is a pseudofirst order reactionat low NO concentration as ln(119862

0119862) = 119896119905 where 119896 is the

apparent rate constant

3 Result and Discussion

TheXRD patterns (Figure 1(a)) of the samples prepared fromthiourea dicyandiamide melamine and urea can be indexedto g-C

3N4[24ndash26] The strongest interplanar stacking peaks

of the conjugated aromatic systems at around 276∘ areindexed to graphitic materials as the (002) peak The smallangle peaks at around 130∘ can be indexed to (100) peak


5 10 15 20 25 30 35 40

CN-U

CN-M

CN-D

CN-T

Inte

nsity

(au

)

2120579 (deg)

(a)

25 26 27 28 29 30

CN-U

CN-M

CN-D

CN-T

Inte

nsity

(au

)

2120579 (deg)

(b)


400 600 800 1000 1200 1400 1600 1800 2000

CN-U

CN-M

CN-D

CN-T

Tran

smitt

ance

(au

)


(a)

2000 2500 3000 3500 4000

CN-U

CN-M

CN-D

CN-T

Tran

smitt

ance

(au

)


(b)



3N4struc-


3N4 In


3N4[29]





6N7)





(a) (b)

(c) (d)





3N4strongly depend








2S and

CO2 release of NH


2Ovapor



300 350 400 450 500 550 600 650Wavelength (nm)

Abs (

au)

CN-U

CN-MCN-D

CN-T

(a)

(Ahv

)12

Band gap (eV)22 24 26 28 3 32 34

CN-U

CN-M

CN-D

CN-T


(b)







2







3

minus+H+


2

NO+ ∙O2

minus997888rarr NO

3

minus

(1)






20

40

60

80

100


Adso

rbed

vol

ume (

cm3g

)

(a)

1 10 100

0

100

200

300

400

500

600

Pore diameter (nm)

dVdD

(cm

3gminus

1)times

105

(b)

10

20

30

40

50

60


Adso

rbed

vol

ume (

cm3g

)

(c)

0

50

100

150

200

250


dVdD

(cm

3gminus

1)times

105

(d)

10

20

30

40


Adso

rbed

vol

ume (

cm3g

)

(e)

02468

101214


dVdD

(cm

3gminus

1)times

105

(f)

50

100

150

200

250


Adso

rbed

vol

ume (

cm3g

)

(g)

0

100

200

300

400

500

600


dVdD

(cm

3gminus

1)times

105

(h)




0 100 200 300 400 500 600 700 800 900 1000

0

20

40

60

80

100 02

exo

Wei

ght l

oss (

)


DSC

(m

Wm

g)

Temperature (∘C)

6724 ∘C

9862

(a)

0 100 200 300 400 500 600 700 800 900 1000

0

20

40

60

80

100

0

2

4

exo

Wei

ght l

oss (

)

minus2

minus4

minus6

minus8

minus10

minus12

DSC

(m

Wm

g)

Temperature (∘C)

6831 ∘C

9554

(b)

0 100 200 300 400 500 600 700 800 900 1000

0

20

40

60

80

100exo

Wei

ght l

oss (

)

0minus2

minus4

minus6

minus8

minus10

minus12

minus14

minus16

minus18

minus20

DSC

(m

Wm

g)

Temperature (∘C)

6495 ∘C

9547

(c)

exo

100 200 300 400 500 600 700 800 900 1000

0

20

40

60

80

100

Wei

ght l

oss (

)

0

minus10

minus20

minus30

minus40

DSC

(m

Wm

g)

Temperature (∘C)

6824 ∘C

5501 ∘C

7769

1407

824

(d)


50

60

70

80

90

100

0 10 20 30 40Time (min)

CC

0(

)

CN-UCN-MCN-D CN-T

(a)

04

035

03

025

02

015

01

005

0

k(m

inminus1)


(b)





3N4


4 Conclusions











Acknowledgments



References






2



2CO3hierarchical

































3N4via doping





























Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


5 10 15 20 25 30 35 40

CN-U

CN-M

CN-D

CN-T

Inte

nsity

(au

)

2120579 (deg)

(a)

25 26 27 28 29 30

CN-U

CN-M

CN-D

CN-T

Inte

nsity

(au

)

2120579 (deg)

(b)


400 600 800 1000 1200 1400 1600 1800 2000

CN-U

CN-M

CN-D

CN-T

Tran

smitt

ance

(au

)


(a)

2000 2500 3000 3500 4000

CN-U

CN-M

CN-D

CN-T

Tran

smitt

ance

(au

)


(b)



3N4struc-


3N4 In


3N4[29]





6N7)





(a) (b)

(c) (d)





3N4strongly depend








2S and

CO2 release of NH


2Ovapor



300 350 400 450 500 550 600 650Wavelength (nm)

Abs (

au)

CN-U

CN-MCN-D

CN-T

(a)

(Ahv

)12

Band gap (eV)22 24 26 28 3 32 34

CN-U

CN-M

CN-D

CN-T


(b)







2







3

minus+H+


2

NO+ ∙O2

minus997888rarr NO

3

minus

(1)






20

40

60

80

100


Adso

rbed

vol

ume (

cm3g

)

(a)

1 10 100

0

100

200

300

400

500

600

Pore diameter (nm)

dVdD

(cm

3gminus

1)times

105

(b)

10

20

30

40

50

60


Adso

rbed

vol

ume (

cm3g

)

(c)

0

50

100

150

200

250


dVdD

(cm

3gminus

1)times

105

(d)

10

20

30

40


Adso

rbed

vol

ume (

cm3g

)

(e)

02468

101214


dVdD

(cm

3gminus

1)times

105

(f)

50

100

150

200

250


Adso

rbed

vol

ume (

cm3g

)

(g)

0

100

200

300

400

500

600


dVdD

(cm

3gminus

1)times

105

(h)




0 100 200 300 400 500 600 700 800 900 1000

0

20

40

60

80

100 02

exo

Wei

ght l

oss (

)


DSC

(m

Wm

g)

Temperature (∘C)

6724 ∘C

9862

(a)

0 100 200 300 400 500 600 700 800 900 1000

0

20

40

60

80

100

0

2

4

exo

Wei

ght l

oss (

)

minus2

minus4

minus6

minus8

minus10

minus12

DSC

(m

Wm

g)

Temperature (∘C)

6831 ∘C

9554

(b)

0 100 200 300 400 500 600 700 800 900 1000

0

20

40

60

80

100exo

Wei

ght l

oss (

)

0minus2

minus4

minus6

minus8

minus10

minus12

minus14

minus16

minus18

minus20

DSC

(m

Wm

g)

Temperature (∘C)

6495 ∘C

9547

(c)

exo

100 200 300 400 500 600 700 800 900 1000

0

20

40

60

80

100

Wei

ght l

oss (

)

0

minus10

minus20

minus30

minus40

DSC

(m

Wm

g)

Temperature (∘C)

6824 ∘C

5501 ∘C

7769

1407

824

(d)


50

60

70

80

90

100

0 10 20 30 40Time (min)

CC

0(

)

CN-UCN-MCN-D CN-T

(a)

04

035

03

025

02

015

01

005

0

k(m

inminus1)


(b)





3N4


4 Conclusions











Acknowledgments



References






2



2CO3hierarchical

































3N4via doping





























Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


(a) (b)

(c) (d)





3N4strongly depend








2S and

CO2 release of NH


2Ovapor



300 350 400 450 500 550 600 650Wavelength (nm)

Abs (

au)

CN-U

CN-MCN-D

CN-T

(a)

(Ahv

)12

Band gap (eV)22 24 26 28 3 32 34

CN-U

CN-M

CN-D

CN-T


(b)







2







3

minus+H+


2

NO+ ∙O2

minus997888rarr NO

3

minus

(1)






20

40

60

80

100


Adso

rbed

vol

ume (

cm3g

)

(a)

1 10 100

0

100

200

300

400

500

600

Pore diameter (nm)

dVdD

(cm

3gminus

1)times

105

(b)

10

20

30

40

50

60


Adso

rbed

vol

ume (

cm3g

)

(c)

0

50

100

150

200

250


dVdD

(cm

3gminus

1)times

105

(d)

10

20

30

40


Adso

rbed

vol

ume (

cm3g

)

(e)

02468

101214


dVdD

(cm

3gminus

1)times

105

(f)

50

100

150

200

250


Adso

rbed

vol

ume (

cm3g

)

(g)

0

100

200

300

400

500

600


dVdD

(cm

3gminus

1)times

105

(h)




0 100 200 300 400 500 600 700 800 900 1000

0

20

40

60

80

100 02

exo

Wei

ght l

oss (

)


DSC

(m

Wm

g)

Temperature (∘C)

6724 ∘C

9862

(a)

0 100 200 300 400 500 600 700 800 900 1000

0

20

40

60

80

100

0

2

4

exo

Wei

ght l

oss (

)

minus2

minus4

minus6

minus8

minus10

minus12

DSC

(m

Wm

g)

Temperature (∘C)

6831 ∘C

9554

(b)

0 100 200 300 400 500 600 700 800 900 1000

0

20

40

60

80

100exo

Wei

ght l

oss (

)

0minus2

minus4

minus6

minus8

minus10

minus12

minus14

minus16

minus18

minus20

DSC

(m

Wm

g)

Temperature (∘C)

6495 ∘C

9547

(c)

exo

100 200 300 400 500 600 700 800 900 1000

0

20

40

60

80

100

Wei

ght l

oss (

)

0

minus10

minus20

minus30

minus40

DSC

(m

Wm

g)

Temperature (∘C)

6824 ∘C

5501 ∘C

7769

1407

824

(d)


50

60

70

80

90

100

0 10 20 30 40Time (min)

CC

0(

)

CN-UCN-MCN-D CN-T

(a)

04

035

03

025

02

015

01

005

0

k(m

inminus1)


(b)





3N4


4 Conclusions











Acknowledgments



References






2



2CO3hierarchical

































3N4via doping





























Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


300 350 400 450 500 550 600 650Wavelength (nm)

Abs (

au)

CN-U

CN-MCN-D

CN-T

(a)

(Ahv

)12

Band gap (eV)22 24 26 28 3 32 34

CN-U

CN-M

CN-D

CN-T


(b)







2







3

minus+H+


2

NO+ ∙O2

minus997888rarr NO

3

minus

(1)






20

40

60

80

100


Adso

rbed

vol

ume (

cm3g

)

(a)

1 10 100

0

100

200

300

400

500

600

Pore diameter (nm)

dVdD

(cm

3gminus

1)times

105

(b)

10

20

30

40

50

60


Adso

rbed

vol

ume (

cm3g

)

(c)

0

50

100

150

200

250


dVdD

(cm

3gminus

1)times

105

(d)

10

20

30

40


Adso

rbed

vol

ume (

cm3g

)

(e)

02468

101214


dVdD

(cm

3gminus

1)times

105

(f)

50

100

150

200

250


Adso

rbed

vol

ume (

cm3g

)

(g)

0

100

200

300

400

500

600


dVdD

(cm

3gminus

1)times

105

(h)




0 100 200 300 400 500 600 700 800 900 1000

0

20

40

60

80

100 02

exo

Wei

ght l

oss (

)


DSC

(m

Wm

g)

Temperature (∘C)

6724 ∘C

9862

(a)

0 100 200 300 400 500 600 700 800 900 1000

0

20

40

60

80

100

0

2

4

exo

Wei

ght l

oss (

)

minus2

minus4

minus6

minus8

minus10

minus12

DSC

(m

Wm

g)

Temperature (∘C)

6831 ∘C

9554

(b)

0 100 200 300 400 500 600 700 800 900 1000

0

20

40

60

80

100exo

Wei

ght l

oss (

)

0minus2

minus4

minus6

minus8

minus10

minus12

minus14

minus16

minus18

minus20

DSC

(m

Wm

g)

Temperature (∘C)

6495 ∘C

9547

(c)

exo

100 200 300 400 500 600 700 800 900 1000

0

20

40

60

80

100

Wei

ght l

oss (

)

0

minus10

minus20

minus30

minus40

DSC

(m

Wm

g)

Temperature (∘C)

6824 ∘C

5501 ∘C

7769

1407

824

(d)


50

60

70

80

90

100

0 10 20 30 40Time (min)

CC

0(

)

CN-UCN-MCN-D CN-T

(a)

04

035

03

025

02

015

01

005

0

k(m

inminus1)


(b)





3N4


4 Conclusions











Acknowledgments



References






2



2CO3hierarchical

































3N4via doping





























Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


20

40

60

80

100


Adso

rbed

vol

ume (

cm3g

)

(a)

1 10 100

0

100

200

300

400

500

600

Pore diameter (nm)

dVdD

(cm

3gminus

1)times

105

(b)

10

20

30

40

50

60


Adso

rbed

vol

ume (

cm3g

)

(c)

0

50

100

150

200

250


dVdD

(cm

3gminus

1)times

105

(d)

10

20

30

40


Adso

rbed

vol

ume (

cm3g

)

(e)

02468

101214


dVdD

(cm

3gminus

1)times

105

(f)

50

100

150

200

250


Adso

rbed

vol

ume (

cm3g

)

(g)

0

100

200

300

400

500

600


dVdD

(cm

3gminus

1)times

105

(h)




0 100 200 300 400 500 600 700 800 900 1000

0

20

40

60

80

100 02

exo

Wei

ght l

oss (

)


DSC

(m

Wm

g)

Temperature (∘C)

6724 ∘C

9862

(a)

0 100 200 300 400 500 600 700 800 900 1000

0

20

40

60

80

100

0

2

4

exo

Wei

ght l

oss (

)

minus2

minus4

minus6

minus8

minus10

minus12

DSC

(m

Wm

g)

Temperature (∘C)

6831 ∘C

9554

(b)

0 100 200 300 400 500 600 700 800 900 1000

0

20

40

60

80

100exo

Wei

ght l

oss (

)

0minus2

minus4

minus6

minus8

minus10

minus12

minus14

minus16

minus18

minus20

DSC

(m

Wm

g)

Temperature (∘C)

6495 ∘C

9547

(c)

exo

100 200 300 400 500 600 700 800 900 1000

0

20

40

60

80

100

Wei

ght l

oss (

)

0

minus10

minus20

minus30

minus40

DSC

(m

Wm

g)

Temperature (∘C)

6824 ∘C

5501 ∘C

7769

1407

824

(d)


50

60

70

80

90

100

0 10 20 30 40Time (min)

CC

0(

)

CN-UCN-MCN-D CN-T

(a)

04

035

03

025

02

015

01

005

0

k(m

inminus1)


(b)





3N4


4 Conclusions











Acknowledgments



References






2



2CO3hierarchical

































3N4via doping





























Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


0 100 200 300 400 500 600 700 800 900 1000

0

20

40

60

80

100 02

exo

Wei

ght l

oss (

)


DSC

(m

Wm

g)

Temperature (∘C)

6724 ∘C

9862

(a)

0 100 200 300 400 500 600 700 800 900 1000

0

20

40

60

80

100

0

2

4

exo

Wei

ght l

oss (

)

minus2

minus4

minus6

minus8

minus10

minus12

DSC

(m

Wm

g)

Temperature (∘C)

6831 ∘C

9554

(b)

0 100 200 300 400 500 600 700 800 900 1000

0

20

40

60

80

100exo

Wei

ght l

oss (

)

0minus2

minus4

minus6

minus8

minus10

minus12

minus14

minus16

minus18

minus20

DSC

(m

Wm

g)

Temperature (∘C)

6495 ∘C

9547

(c)

exo

100 200 300 400 500 600 700 800 900 1000

0

20

40

60

80

100

Wei

ght l

oss (

)

0

minus10

minus20

minus30

minus40

DSC

(m

Wm

g)

Temperature (∘C)

6824 ∘C

5501 ∘C

7769

1407

824

(d)


50

60

70

80

90

100

0 10 20 30 40Time (min)

CC

0(

)

CN-UCN-MCN-D CN-T

(a)

04

035

03

025

02

015

01

005

0

k(m

inminus1)


(b)





3N4


4 Conclusions











Acknowledgments



References






2



2CO3hierarchical

































3N4via doping





























Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of




3N4


4 Conclusions











Acknowledgments



References






2



2CO3hierarchical

































3N4via doping





























Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of




















3N4via doping





























Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of










Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of

research article the multiple effects of precursors on the...

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