Our Chemical Route to Nanotechnology: An Overview

H. S. Virk1 & Poonam Sharma2

1Nanotechnology Laboratory, DAV University, Jalandhar-144008, India

2Department of Chemistry, St. Francis Xavier University, Nova Scotia, Canada

Routes to Nanotechnology

• Physical, chemical, biological and nature’s self assembly.

• Top-down and bottom-up approaches.• Chemical route to nanotechnology is simpler,

cheaper and allows fabrication at bench top conditions.

• Reverse micelles (microemulsions route) is a versatile method to produce a variety of nanoparticles.

Bottom Up Techniques Used

• Reverse micelles, co-precipitation, solvo-thermal, sol-gel and seed growth technique.

• Quantum dots, nanorods and nanoneedles of Barium Carbonate, Barium Oxalate, Iron Oxalate, Barium hexaferrite, Zinc Oxide, Cadmium Sulphide, Cadmium Oxide and Silver prepared for characterization using SEM, TEM,

UV-Vis, FTIR, XRD, TGA & VSM techniques.

Reverse Micelle Schematic

Nanoparticle Synthesis (ME route)

SEM image of Barium Carbonate Nanorods

TEM images of Barium Carbonate Nanorods

TEM images of Iron Oxalate and Barium Oxalate Nanocrystals

TEM image of CdO Quantum Dots

Conversion of Quantum Dots of Conversion of Quantum Dots of CdO to Nanorods using EDA CdO to Nanorods using EDA

CdS Nanocrystals(CTAB+n-butanol)

CdS Nanoneedles(CTAB+n-hexanol)

CdS Quantum Dots( molar ratio=5)

CdS Nanorods (molar ratio=15)

Ba-M Hexaferrite Crystals (ME)

Ba-M Hexaferrite Crystals (CP)

Ba-hexaferrite ME(after calcination)

Ba-hexaferrite CP(after calcination)

Hysteresis loops of Ba-hexaferrite nanoparticles (CP & ME samples)

SEM image of ZnO Nanocrystals in Ethanol and Nanorod(adding EDA)

TEM image of Ag quantum dots and embedded nano particles

Electrochemical Synthesis

• Electrochemistry has been used to fabricate nanowires and heterojunctions of Cu, Cu-Se and Cd-S. The results of our investigations can be exploited for fabrication of nanodevices for application in opto-electronics and nano- electronics. During failure of our Experiments, exotic patterns (nanoflowers, nanocrystals, nanobuds) were produced under nature’s self assembly.

Electrolytic CellElectrolytic Cell

Electrodeposition of Nanowires

• The electrolyte used is CuSO4.5H2O acidic solution. The rate of deposition depends upon current density, inter-electrode distance, cell voltage, electrolyte concentration and temperature etc. The technique has been tested for growth of nanowires of Copper and heterojunctions of Cu-Se and Cd-S electrochemically using anodic alumina and polymer templates (Nuclepore Filters).

Atomic Force Microscope(NT-MDT)

AFM image of hexagonal pores of AFM image of hexagonal pores of Anodic Alumina Membrane (AAM)Anodic Alumina Membrane (AAM)

SEM Images of Cu Nanowires using SEM Images of Cu Nanowires using Electrodeposition TechniqueElectrodeposition Technique

Capping Effect of Current VariationCapping Effect of Current Variation

Copper Lillies grown due to over- Copper Lillies grown due to over- deposition of Copper in AAM deposition of Copper in AAM

Copper Nanoflowers grown in Polymer Template (100nm pores)

Copper Marigold (Gainda) Flower

A Garden of Copper NanoflowersA Garden of Copper NanoflowersA Garden of Copper NanoflowersA Garden of Copper Nanoflowers

SEM micrograph of Nanocrystals of SEM micrograph of Nanocrystals of Polycrystalline CopperPolycrystalline Copper

XRD Spectrum of polycrystalline XRD Spectrum of polycrystalline Copper nanocrystalsCopper nanocrystals

Position [°2Theta] (Copper (Cu))

10 20 30 40 50 60 70

Counts

0

20000

40000

60000

36.6

37 [

°]

38.2

83 [

°]

43.4

61 [

°]

45.4

48 [

°]

48.9

20 [

°]

50.5

80 [

°]

54.3

04 [

°]54.9

56 [

°]

64.8

09 [

°]

74.2

99 [

°]

KK1

XRD spectrum of Cu nanowiresXRD spectrum of Cu nanowires

Position [°2Theta] (Copper (Cu))

30 40 50 60 70 80 90

Counts

0

400

1600

Cu polycrystalline

SEM Image of CdS NanowiresSEM Image of CdS Nanowires

HRTEM image showing CdS HRTEM image showing CdS Nanowire & Heterojunctions Nanowire & Heterojunctions

I-V plot of CdS Nanowire arrays I-V plot of CdS Nanowire arrays showing RTD characteristics showing RTD characteristics

SEM image of Cu-Se NanowiresSEM image of Cu-Se Nanowires

Cu-Se nanowires exhibit p-n Cu-Se nanowires exhibit p-n junction diode characteristicsjunction diode characteristics

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