S1

Supplementary Information:

Super-Resolution Fluorescence Mapping of Single-nanoparticle Catalysts Reveals

Spatiotemporal Variations in Surface Reactivity

Yuwei Zhanga,b,1, J. Matthew Lucasc,d,1, Ping Songa,b,1, Brandon Beberwyckd,e, Qiang Fua,b, Weilin Xua,b,2,

and A. Paul Alivisatosd,f,g,2

aState Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese

Academy of Science, Changchun 130022, People’s Republic of China; bJilin Province Key Laboratory of Low

Carbon Chemical Power, Changchun Institute of Applied Chemistry, Chinese Academy of Science, Changchun

130022, People’s Republic of China; cDepartment of Mechanical Engineering, University of California at Berkeley,

CA 94720; dMaterials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720;

eDepartment of Materials Science and Engineering, University of California at Berkeley, CA 94720; fDepartment

of Chemistry, University of California at Berkeley, CA 94720, and gKavli Energy Nano Science Institute,

University of California, Berkeley, California 94720, United States

1These authors contributed equally to this work.

*To whom correspondence. E-mail: weilinxu@ciac.ac.cn (W. X.); alivis@berkeley.edu (A. P. A.)

1. Experimental

1.1. Synthesis of Sb-doped TiO2 nanorods

Anatase TiO2 nanorods were synthesized with a modified method according to the literature

with oleic acid (OA, from Sigma-Aldrich) and titanium (IV) isopropoxide (TTIP, from

Sigma-Aldrich) at 270°C (S1). Simply, according to the reference, short TiO2 nanorods (~25

nm) were synthesized and then used as seeds to synthesize the longer TiO2 nanorods used in

this experiment. This different from (S1) where no seeds were used. Pure, long TiO2 nanorods

(90-150 nm) were obtained by conducting size-selective precipitation from hexane/ethanol

solution containing the product mixture. The final, pure TiO2 in hexane was obtained for the

next step: doping. For the doping step, certain amount of tris (dimethylamido) antimony

([(CH3)2N]3Sb) (from Sigma-Aldrich) dissolved in hexane was injected into the purified

pristine TiO2 nanorods solution in hexane with atomic ratio Sb/Ti = 1/100. The obtained

mixture was stirred for 24 h under Argon atmosphere to get even distribution of Sb precursor

on TiO2 nanorods surface. The obtained mixture solution was purified once with

size-selective precipitation and then named Solution A. The final Sb-doped TiO2 nanorods

were obtained by drying the above Solution A in air, then sintering in air on a surface at

500°C for 2 h to remove the surface ligand oleic acid. It has been found the annealing of

anatase TiO2 at 500°C can maintain the anatase phase of TiO2 (S2).

Particle morphologies of doped or undoped TiO2 nanorods were examined by transmission electron

microscopy (TEM, JEOL LEM-4000FX) at 200 kV. Diffuse reflectance spectra were also obtained for

the dry-pressed disk samples using a UV-Vis-NIR spectrophotometer (JASCO) equipped with ISN-470

integrating sphere assembly. Reflectance spectra were referenced to MgO.

S2

Fig. S1. The TEM image of short TiO2 nanorods as seeds for the growth of longer Sb-doped

TiO2 nanorods shown in Fig. 1a in the main text.

Fig. S2. The statistic analysis of the length (A) and diameter (B) of Sb-doped long TiO2

nanorods used here.

Fig. S3. Diffuse reflectance spectra for undoped TiO2 nanorods and Sb-doped TiO2 nanorods.

The above diffuse reflectance and absorbance spectroscopy revealed that the band gap of

the unmodified TiO2 nanorods (white) was approximately 3.3 eV, while the onset of the

optical absorption of the Sb-doped TiO2 nanorods (yellowish) was lowered to about 1.9eV

(~630 nm).

A BA B

S3

1.2. Single molecule experiment on Sb-doped TiO2 nanorods

For typical single molecule experiments, the diluted Solution A with Sb-doped TiO2 nanorods

was spin-coated on a quartz slide surface. After drying in air, the quartz slide was annealed in air

at 500°C for 2 h to remove the ligand oleic acid. After cooling to room temperature, the quartz

slide was washed with DI water to remove unbound nanorods. Using a previously reported

method (S3), a flow cell was made for single molecule experiments. In the experiments, the first

step is photobleaching the fluorescent dust or impurities in the channel by flowing in a blank

air-saturated phosphate (50mM, pH7.3) buffer with flow rate 20 uL/min under high power density

green laser (514 nm) light for 30 min. In this way most of the fluorescent impurities could be

photobleached. The remaining dusts with stable fluorescence then were used as markers. After that

buffers containing 1uM Amplex-Red was flowed through the flow cell illuminated with laser at

approprite intensity.

Single-molecule fluorescence measurements on Sb-doped TiO2 were performed on a

homebuilt prism-type totalinternal reflection (TIR) fluorescence microscope based on a Zeiss

Axiovert 135 TV inverted microscope. A continuous wave 514 nm laser beam (Lexel Laser)

of 10-15 mW was focused onto an area of ~138 × 138 μm2 on the sample to directly excite

both the Sb-doped TiO2 nanorods and the fluorescence of resorufin. The fluorescence of

resorufin was collected by a 60X NA1.2 water-immersion objective (UPLSAPO60XW,

Olympus), filtered by a filter (HQ545LP), and projected onto a camera (Andor iXon EMCCD,

DV887DCS-BV), which is controlled by an Andor iXon software. All optical filters are from

Chroma Technology Corp. The movies are analyzed using a home-written IDL program and

Matlab program, which extracts the fluorescence intensity trajectories from localized

fluorescence spots individually across the entire movie. The intensity of each bright spot in an

image is obtained by integrating the signal counts over an area of ~1×1 μm2.

2.1. Synthesis of Au nanoplates

First, Au seeds were synthesized. Simply, 1 mL of 10 mM sodium citrate solution and 1mL

of 10 mM HAuCl4 solution was added to 37 mL of nanopure H2O in a 50 mL beaker, while

stirring. Meanwhile, a solution of 100 mM NaBH4 was prepared and placed in an ice-bath for 10

min. Once cold, 1 mL of 100 mM NaBH4 solution was added to the sodium citrate-HAuCl4

solution (faint yellow color). The resulting solution immediately turned ruby red in color, which

indicated the formation of Au nanoparticles. The seed solution was continuously stirred for five

minutes after NaBH4 addition, after which time the stirring was stopped and the stir bar was

removed from the solution. The Au seeds were left undisturbed at room temperature for 2~3 h to

allow for hydrolysis of any remaining NaBH4 before further use. The synthesis of Au nanoplates.

A single 100 mL growth solution consisting of 0.25 mM HAuCl4 in 50 mM CTABr, maintained at

250C, was used for nanoplates. To this solution was added 550uL of 100mM ascorbic acid, at

which time the solution turned colorless, which indicated the reduction of Au3+

to Au+. Next,

550uL of 100 mM NaOH was added, raising the final pH to 4, and 10uL of 100 mM NaI was

added to achieve a final concentration of 10uM NaI. To initiate growth, 100uL of Au seed solution

was added, briefly stirred, and allowed to sit overnight in a water bath maintained at 250C.

2.2. Single-molecule chemical reaction experiments on individual Au nanoplates.

Single-molecule fluorescence measurements were performed on a homebuilt prism-type total

internal reflection (TIR) fluorescence microscope based on an Olympus IX71 inverted microscope.

S4

A continuous wave circularly polarized 532 nm laser beam (CrystaLaser, GCL-025-L-0.5%) of

4-6 mW was focused onto an area of ~80×80 m2 on the sample to directly excite the fluorescence

of resorufin. The reactants with 100 nM Resazurin and 2 mM hydroxylamine (NH2OH) were

flowed through over the dispersed Au nanoplates on quartz slide in the micro-flow cell. The

fluorescence of resorufin was collected by a 60X NA1.2 water-immersion objective

(UPLSAPO60XW, Olympus), filtered by two filters (HQ550LP, HQ580m60), and projected onto

a camera (Andor iXon EMCCD, DU-897U-CS0-#BV), which is controlled by an Andor IQ

software. All optical filters are from Chroma Technology Corp. The movies are analyzed using a

home-written IDL program, which extracts the fluorescence intensity trajectories from localized

fluorescence spots individually across the entire movie. The intensity of each bright spot in an

image is obtained by integrating the signal counts over an area of ~1×1 m2.

A flow cell, 100 m (height) ×2 cm (length)×5 mm (width), formed by double-sided tapes

sandwiched between a quartz slide (Technical Glass or Finkenbeiner) and a borosilicate coverslip

(Gold Seal®), was used to support catalysts and hold aqueous sample solutions for

single-molecule fluorescence measurements. A suitable amount of colloidal Au nanoplates

solution was spin-coated onto quartz slide, and then rinsed several times with MilliQ water to

remove unbound nanoparticles. On the quartz slide two holes were drilled to connect to

polyethylene tubing and a syringe pump for continuous solution flow at 10 L/minute.

For the ex-situ TEM experiments, the Au nanoplates were dispersed on a copper grid with

special marks on. In order to fix the nanoplates on the carbon film, a very diluted Nafion (a

polymer) solution (0.1%) was added to the solution. Before the reaction, we took some TEM

images from several areas with special marks so that we can possibly find them again after

the reaction. After that, the copper grid was embedded in a normal flow cell for single

molecule experiments. Then reactant solution was flowed into the cell with the same setup as

the normal single molecule experiments under laser irradiation. After 8hr of reaction, the

copper grid was taken out carefully and detected under TEM again to find the areas that have

been observed before the reaction. By this way, we can see the possible variations induced by

the reaction or catalysis on the shape of Au nanoplates.

3. Single-molecule catalysis mapping on individual nanocatalysts

In our experiments, the time of 13 or 10 hours doesn’t mean a single movie is 10+ hours long.

Instead, 20+ movies have been taken sequentially for a total time of 10+ hours. Each movie is

~30 minutes long.We did not observe obvious lateral drift of our system in 2 hours after

taking precautions to stabilize our optical system. These precautions include flattening the

laser table, fixing the flow cell very securely to the optical system, and finally allowing the

system to rest for 30 minutes before the beginning of data acquisition to allow any fast drift to

settle. We also minimize any disturbances or traffic in the optical room during data

acquisition. Here we need to explain how we correct for drift, which is somewhat complicated

because it occurs on two different time scales. This has been added to the text as well for

clarification. First, on the longer time scales, we use big, bright marks on our substrates as

reference and are present in each movie taken. Since the reference marks remain constant

through all the acquisitions taken on the same area, the reference mark is used to monitor any

lateral drift of the system. At the beginning of an acquisition we draw a square around each

mark on the computer monitor (as shown in the following Fig. S4A). If the reference marks

S5

are not within the squares at the beginning of the next acquisition we carefully adjust the

sample stage to return the reference marks to their original position. Second, on a

frame-by-frame time scale, we also account for drift during a given movie acquisition. We

analyzed the precise positions of the marks in each frame by doing 2D Gaussian fitting with

the point-spread-function as has been used in prior reports (S4). Any drift of these marks in

each frame can then be applied to the catalysis mapping in that same frame.

To determine the center position of the fluorescence PSF of individual single resorufin

molecules on single nanocatalysts, an image area of 13×13 pixels (~3.5×3.5 um2) with the

bright point centered was selected out for two-dimensional (2D) Gaussian fitting. Then we

used the following equation for 2D Gaussian fitting to localize the center position of the

fluorescence PSF:

(S-1)

Here I(x,y) is the fluorescence intensity counts of the product molecule in the image at

position (x,y), the exponential term is a 2D Gaussian function, and δ is half of the pixel size.

Along the x or y axis, the integration over each pixel is done numerically by dividing each

pixel into 11 equal segments (further increasing the number of segments does not improve the

fitting accuracy). Because the laser field in our experiment is not homogeneous over the entire

illumination area (note the area analyzed for one molecule is very small relative to the laser

illumination area of ~80×80 um2, though), we used a sloping plane, A+Bx+Cy, to account for

the background in the fitting. (x0,y0) gives the center position of the PSF (S4).

In order to precisely map molecule position on individual nanoparticles, we considered the

positional stability of the system by considering its focal stability and lateral stability (S5).

We found no obvious defocusing in two hours with tight fixing of all the optic pieces and the

flow cell. For the lateral stability of the optical system, large bright fluorescent spherical dust

particles, which do not blink and cannot be photobleached in several hours, were found and

used as reference markers for factoring out lateral drift in the recorded movie (S6). The

system experiences lateral drift of tens of nanometers on the time scales of hours (an example

for Sb-TiO2 system shown in Fig. S4B). This drift is corrected by aligning and registering all

images using the positions of the dust particle emitters, which can be obtained with up to 10-

nm accuracy using 2D-Gaussian fitting.

Drift in the z-direction is not an issue because our resolution is bigger than the thickness of

the sample. For the two types of nanocatalysts used in the present wok, one is TiO2

nanorods with diameter less than 5 nm, the other one is Au nanoprism with thickness about 8

nm. These two nanoparticles only lie down, rather than stand vertically, on the quartz slide

surface, just as they do in TEM images (Fig. 1 and Fig. S17). The thickness of these

samples in z-direction is less than the resolution of about 20 nm. To the best of our

knowledge, the best spatial resolution with optical super-resolution method is at best 10 nm.

That means the best 3D imaging method and analysis along the z-direction cannot distinguish

the top and bottom of such thin nanocrystals as those we used in this study.

S6

The 3D imaging methods along the z-direction only work for the samples with large sizes,

such as some biological systems. For the nanoparticles used in this study, which are both

thinner than our spatial resolution and are almost certainly lying flat on the substrate, the

z-drift analysis would not be able to distinguish drift from the top to the bottom of the

nanocrystal. Or the z-direction analysis is not applicable to such thin samples.

Fig. S4.(A) Scheme to show the drift correction in a large length scale. (B)Typical lateral drift

from the marker in x- and y-directions. Data shown are taken from part of a long movie (time

interval is 0.1 s).

4. Position accuracy:

Repeated observation of a single fixed dye molecule. To ensure positional accuracy of the

molecule over time, we determined the positions of a single fluorescent molecule fixed in a

Nafion film from each frame in one ton by 2D Gaussian fitting. Fig. S5 shows the fitted

positions for the molecule at each frame under the optical setup for Sb-doped TiO2 catalytic

system. All these fitted positions are located within 40 × 40 nm2.The full width at half

maximum of the corresponding Gaussian distribution, which is generally defined as the

resolution (S7), equals about 20 nm in both x- and y-directions.

Fig. S5. Repeated localization of a single, fixed resorufin molecule from one ton. The full

width at half maximum of Gaussian distribution fitted to these positions indicated by a red

circle. The red square is the averaged center of this molecule.

A

B

S7

5. The effect of molecule diffusion on the distribution of product molecules over a

larger spatial area than the real dimension of the TiO2 nanorod.

Prior experimental (S8-S9) and theoretical (S10-S11) literatures have studied the diffusion of

molecules across surfaces in a boundary layer (Fig. S6). It is known that the diffusion

coefficient (D) quickly decreases the closer the molecule is to the solid surface. That means

the D value of molecules close to a solid surface is much smaller than the coefficient value of

molecule in free solution. For the case of resorufin (D = 4.8×10-10

m2 s

-1 in free solution)

(S12), we do not know its exact D value when it adsorbs on (or is very close to the)

nanocatalyst surface, but we do know it must be much smaller than 4.8×10-10

m2 s

-1. Since the

general simulation shows that the D value could decrease up to 4-6 orders of magnitude when

the molecule is close enough to the solid surface (S11), we assume 5 orders of magnitude

decrease in diffusion and approximate D for resorufin near the surface as 4.8×10-15

m2 s

-1.

Fick’s law defines the relationship between the distance travelled, d, by a molecule during

time, t, where D is the diffusion coefficient.

(S-2)

Using this equation, we can assess the distance of molecule diffusion within the time of

100ms (0.1s) to be about

The d value of 30 nm indicates the distance resorufin diffuses after its formation on the active

site should be in the range of tens of nanometers on the timescale of 100ms, which is our

image acquisition cycle time. Therefore diffusion of the product molecules within the static

fluid boundary layer near the nanocatalyst could reasonably be expected to account for much

of the apparent broadening observed in Fig 2.

Fig. S6. The scheme to show the results induced by the boundary layer on a nanoparticle

surface. Due to the boundary layer, the product molecules seen from super-resolution

mapping will be distributed in a wider range (l2) than the real dimension (l1) of nanoparticles

Di

DoDi << Do

Di : diffusion coefficient in the boundary layer;

Do : diffusion coefficient out of the boundary layer;

: solid nanoparticle.

l1

l2

>l1l2

S8

6. The calculation of error bar for TOF from individual nanocatalyst

From atypical single-particle fluorescence intensity trajectory, such as the one shown in

Fig. 1d, we can get two series of waiting times, schematically shown in Fig. S7. The first

series, {toff1, toff2, toff3…..}, is the dark waiting time before a product molecule is formed. The

second series, {ton1, ton2, ton3…..}, is the bright waiting time before a newly formed product

molecule drifts away. The value of toff1 + ton1is the time needed for the formation of a product

molecule or for a complete turnover of reaction. The inverse of that, (1/ (toff1 + ton1)), is the

turnover frequency (TOF, s-1

).

From the formation of many individual product molecules on a single nanocrystal, we

obtain a series of TOF: {1/ (toff1 + ton1), 1/ (toff2 + ton2), 1/ (toff3 + ton3), …} From this series of

values of TOF, we finally obtain an averaged TOF and the corresponding Standard Error of

Mean (s.e.m), such as the one shown in the main text: 0.22 ±0.01 s-1

, where the 0.22 is the

averaged TOF based on a series of individual TOF, the 0.01 is the corresponding s.e.m.

Fig. S7. The scheme to show the calculation of the averaged TOF and the corresponding

error bar (standard error of mean, s.e.m.).

7. Comparison of the productivities between the middle and the ends on the same

nanorods.

Fig. S8. Statistical analysis about the difference of the productivities between the middle

and the ends. TOFm: averaged TOF of the middle of a rod; TOFe: average TOF of the two

ends of the same rod.

ton1

toff1

ton2 ton3 ton4 ton5 ton6 ton7

…..

toff2 toff3 toff4 toff5 toff6

Flu

ore

sc

en

ce

Inte

ns

ity

Time

Time of each turnover: { (toff1 + ton1), (toff2 + ton2), (toff3 + ton3) , (toff4 + ton4),….}

Turnover frequency (TOF): { 1/(toff1 + ton1), 1/(toff2 + ton2), 1/(toff3 + ton3) , 1/(toff4 + ton4),….}

S9

8. Additional single molecule catalysis mapping of single nanocatalyst.

Fig. S9. Time sequential mapping for another Sb-doped TiO2 nanorods, just like the one

shown in Fig. 2 in the main text. The yellow arrow approximately shows the location of the

nanorod.

9.Time-dependent aspect ratio (Rasp) of the distribution of localization events from single

nanorods.

Alternatively, in order to observe the activity fluctuation in different ways, we analyzed the

time-dependent aspect ratio of the distribution of localization events from individual

nanoparticle. For that goal, all the localization events were divided into five parts in the time

order just like that shown in Fig. 2 and Fig.3 in the main text. As the insert shows in the

following Fig. S10F, the maximum distance between 95% of data points (excluding ~5%

outliers) were used approximately as the distribution width (Wx or Wy) of each part of

localization events in either x- or y-direction. Based on the obtained Wx and Wy, we obtained

the aspect ratio (Rasp=Wy / Wx) of the distribution of localization events for each particle at

different time (noted as 1, 2, 3, 4 and 5 in the time order, which correspond to the

distributions shown in A,B,C,D, and E, respectively). Rasp close to 1 is typical of activity

near the middle of the nanorod while Rasp close to 2 is typical of activity spread across both

ends of the nanorod.

When tracking the time-dependent variation of Rasp on individual TiO2 nanorods, we find that

Rasp increased from a small value (~1) to a large value for all these individual nanorods. In

some instances, we also observed Rasp decrease after a maximum. The increase of Rasp (Fig.

S10-S14) indicates the shift or extension of active domain from the middle of the rod to the

two ends. The decrease of Rasp after a maximum could be due to the activity fluctuation of

different parts of the rod. The activity recovery or deactivation of part of an individual

nanorod also can be observed from the variation of Rasp (such as Fig. S12 and S13).

Aggregated observations across multiple individual nanorods indicate there are

particle-to-particle differences in the time scale of shift of active domain (Fig. S14).

2

9

18

A B C D E I

F G H I

J K L M

N

S10

Fig. S10. (A-E)The time-sequence of two-dimensional histograms of five parts of

localizations on an individual nanorod shown in Fig.2. (A): the first part of localization events;

(B): the second part of localization events; (C): the third part of localization events; (D): the

fourth part of localization events; and (E): the fifth part of localization events. The blue

ellipse indicates the distribution of all localization events on the nanorod, while the yellow

ellipse indicates the distribution of localization events during the particular time interval. (F)

Time-dependence of Rasp obtained from (A) to (E) on the single nanorod. The inset in (F)

shows the calculation of Rasp of the distribution of localization events from the distribution

width of Wx and Wy.

Fig. S11. The second example to show the time-dependent variation of Rasp on an individual

TiO2 nanorod, just like that shown in Fig. S10. In sample it took longer before the center of

activity shifted from the center to the ends than the sample in Fig. S10.

S11

Fig. S12. The third example to show the time-dependent variation of Rasp on individual TiO2

nanorod. This nanorod shows the fluctuation of catalytic activity at the ends of the nanorod.

Fig. S13. The fourth example to show the time-dependent variation of Rasp on individual TiO2

nanorod shown in Fig. S9. This nanorod shows clearly the activity recovery of the middle

and the activity fluctuation of the ends.

S12

Fig. S14. The time-dependence of Rasp on 83 individual TiO2 nanorods. The thick pink curve

is the average. The error bar is the standard deviations (SD).

The statistical analysis (Fig. S14) from multiple individual nanorods indicates there is

particle-to-particle difference in the time scale of shift of active domain.

10. Structural heterogeneity of different rods

Fig. S15. Typical HRTEM to reflect the structural heterogeneity of nanorods. From top to

bottom: a bulb-shaped and an undefined end facet; very flat ends on this rod; possible

side growth on the rod; both rough and smooth ends of rods in the same frame; rod is

tapered and rough.

S13

11. FFT along a High resolution TEM image of a Sb-doped TiO2 nanorod.

Fig. S16. The FFT along a HRTEM image of a Sb-doped-TiO2 nanorod.

12. The characterization of Au nanoplates.

Fig. S17. The characterization of Au nanoplates. (A) Typical TEM images of Au nanoplates.

(B) HRTEM image of part of a Au nanoplate; the inset shows the d-space to be about 0.25 nm.

(C) Selected area (electron) diffraction (SAED) from a Au nanoplate. The spots in (C) marked

by a box, triangle, and circle correspond to 1/3(422), {220), and (422) diffractions,

respectively. (D) XRD patterns of the obtained Au nanoprisms deposited on a glass slide.

2.5AO

A B

C D

S14

Fig. S17A presents some typical Au nanoplates of regular triangular shape. Fig. S17B is

the HRTEM image of the edge part of one Au nanoplate. The lattice spacing (2.5 Å) agrees

fairly well with the (111) lattice spacing of Au single-crystal structure. This observation is

strongly consistent with the SAED analyses (Fig. S17C). Three sets of spots can be identified

based on d-spacing. The set with a spacing of 1.41 Å is due to the (220) reflection of fcc Au.

It indicates that the prepared nanoplates are single-crystalline with (111) lattice planes as the

basal planes. The outer set with a lattice spacing of 0.81 Å can be indexed to the (422) Bragg

reflection. These two sets of reflection are both allowed by a fcc lattice. The inner set with a

lattice spacing of 2.41 Å is believed to originate from the forbidden 1/3{422} reflection (S13).

This forbidden reflection has also been observed in other Ag or Au nanostructures in the form

of thin plates or films bounded by atomically flat surfaces. According to the results of Pileni

et al., (S13) such 1/3(422)forbidden reflections observed on the plate-like structures of Au or

Ag should be attributed to (111) stacking faults lying parallel to the (111) surface and

extending across the entire nanoplate. The hexagonal nature of the diffraction spots supports

the fact that Au nanoprisms are highly [111]-oriented, with the planar face perpendicular to

the electron beam. A typical XRD pattern for the as-prepared Au nanoprisms is shown in Fig.

S17D, four peaks assigned to (111), (200), (220), (311) reflections are face-centered-cubic

(fcc) metallic Au structure (ICCD, PDF2 65-8601). It is worth noting that the intensity ratio of

(111) to (200) peaks is much higher than the standard value, indicating that the main product

is single crystalline with (111) planes as two basal surfaces, and the (111) facets tend to be

oriented parallel to the substrate surface. For Au structure of this morphology, it is quite

common that the lowest free energy of the (111) planes can induce the formation of plate like

structure in chemical method (S14, S15).

More data to confirm the single-crystallinity in Au nanoplates

Fig. S18. Typical bright field and electron diffraction of entire single nanoplates on multiple

nanocrystals (A←→D; B←→E; C←→F). All the nanoparticles analyzed produced

single-crystal diffraction patterns.

A B C

D E F

S15

Proof (1) of the flatness of Au nanoplates: rocking angle bright field TEM

Fig. S19. Typical bright field images of two Au nanoplates at different alpha tilt angles. (A)

with 0° tilt; (B) with 20° tilt; (C) with 40° tilt

A flat object, when tilted, should lose its original aspect ratio. The red and green dashed

triangles are copied from the 0° tilt case and meant to guide the eye to the distortion of aspect

ratio.

Proof (2) of flatness: Moire patterns are unlikely in non-planar structures

Fig. S20. The observation of Moire patterns in bright field. They are due to small rotational

misalignments in the crystal structure. They are unlikely unless the crystals can lay on top of

each other. Such an alignment is unlikely in pyramidal or other non-planar structure.

0° tilt 20° tilt 40° tilt

A B C

S16

Fig. S21. The size (side-length) distribution of Au nanoplates.

13. Characterization of the gold nanoplates with Atomic force microscopy (AFM)

Fig. S22. Typical AFM image of Au nanoplates. The outline of surface-flat gold nanoplates

with triangle-shape just like that shown in TEM image (Fig. S17A). The thickness of the

nanoplates is about 8 nm.

Fig. S23.Time sequential mapping for another Au nanoplate, just like the one shown in Fig. 3

in the main text. The white triangle approximately indicates the location of the Au nanoplate.

A B

K

C D E F

G H I J L

M N O P Q

S17

14.Time-dependent aspect ratio (Rasp) of the distribution of localization events from

single Au nanoplates.

As for the triangular Au nanoplates, the Rasp was also obtained in the same way as above for

TiO2nanorods. However, as shown below (Fig. S24-S26), the Rasp (<Rasp>=1.02 ± 0.04) on

single nanoparticle is approximately independent of the time. Also the difference of

time-dependent Rasp among different individual Au nanoparticles is very small as shown in

Fig. S26.

Compared with that observed on individual TiO2 nanorods shown above (Fig. S10-S14), the

Rasp for individual Au nanoplates is much less informative. The big difference observed here

between Rasp for individual TiO2 nanorods and the Rasp for individual Au nanoplate probably

could be attributed to different activity patterns between different (1D vs. 2D) nanocatalysts

shown in Fig. 2 and Fig. 3 in the main text.

Fig. S24. (A-E)The time-sequence of two-dimensional histograms of five parts of

localizations on single Au nanoplate shown in Fig.3(C-G) in the main text. (A): the first part

of localization events; (B): the second part of localization events; (C): the third part of

localization events; (D): the fourth part of localization events; and (E): the fifth part of

localization events. The dotted triangle indicates the distribution range of all localization

events. (F) Time-dependence of Rasp obtained from (A) to (E) on the single Au nanoplate.

Fig. S25. Time-dependence of Rasp obtained from 2D mapping (A) to (E) on the single Au

nanoplate shown in Fig. S23.

A B C D E

F

A

B

C

D

E

A

B

C DE

S18

Fig.S26. Time-dependence of Rasp on 67 individual Au nanoplates. The thick blue curve is the

average. The error bar is the standard deviations (SD).

Fig. S27The morphology of the same set of Au nanoplates studied with TEM

before(A)/after(B) the fluorogenic reaction. The symbols (*, #, @), circles and arrows

mark the variations of corners and shapes of Au nanoplates after reaction.

Fig. S28. Scheme to show the relationship among the surface reconstruction (blue), dynamic

reactivity pattern fluctuation (yellow) and the reactivity fluctuation of single nanocatalyst

(red).

A B

catalysis/reaction-driven

surface reconstruction

reactivity fluctuation

of Single nanocatalystdynamical fluctuation

of reactivity pattern

different Natural

propertiesof active sites

S19

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