SnNb2O6 Ultrathin

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Fabrication of 0D/2D carbon nitride quantum dots/ SnNb2O6 ultrathin nanosheets with enhanced photocatalytic hydrogen production Bifu Luo, Yuanzhi Hong, Di Li, Zhenyuan Fang, Yaping Jian, and Weidong Shi ACS Sustainable Chem. Eng., Just Accepted Manuscript • DOI: 10.1021/ acssuschemeng.8b03006 • Publication Date (Web): 10 Sep 2018 Downloaded from http://pubs.acs.org on September 11, 2018

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ACS Sustainable Chemistry & Engineering

Fabrication of 0D/2D carbon nitride quantum dots/SnNb2O6

ultrathin

nanosheets

with

enhanced photocatalytic hydrogen production Bifu Luoa, Yuanzhi Hongb, Di Lic, Zhenyuan Fanga, Yaping Jiana and Weidong Shia* a

School of Chemistry and Chemical Engineering, Jiangsu University, 301

Xuefu Road, Zhenjiang, 212013, People’s Republic of China b

School of Materials Science and Engineering, Jiangsu University, 301

Xuefu Road, Zhenjiang, 212013, People’s Republic of China c

Institute for Energy research, Jiangsu University, 301 Xuefu Road,

Zhenjiang, 212013, People’s Republic of China Authors’ email address: Bifu Luo: [email protected]; Yuanzhi Hong: [email protected]; Di Li: [email protected]; Zhenyuan Fang: [email protected]; Yaping Jian: [email protected] Corresponding author: Weidong Shi: [email protected]. Abstract: 2D nanosheet photocatalysts with appropriate band structure have arouse a great deal of research interest owing to the unique structural and electronic properties. In this work, carbon nitride quantum dots (CNQDs) with upconversion property was constructed on SnNb2O6

ACS Paragon Plus Environment

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ultrathin nanosheets by a facial hydrothermal process. The as-prepared CNQDs/SnNb2O6

0D/2D

nanocomposite

exhibited

an

enhanced

photocatalytic performance of H2 production under visible light irradiation (λ>420 nm). The upconversion behavior of CNQDs endow the CNQDs/SnNb2O6 nanocomposite with the ability of photocatalytic H2 production at wavelengths greater than 600 nm. Moreover, the introduced CNQDs could serve as effective electron collectors and promote the transfer of photo-generated charge carriers, which is elucidated by the transient photocurrent response and electrochemical impendence spectra. Finally, a plausible photocatalytic mechanism was proposed for CNQDs/SnNb2O6 nanocomposite toward the H2 production from water splitting. Keywords: Carbon nitride quantum dots; SnNb2O6 nanosheets; H2 production; Up-conversion property INTRODUCTION As a renewable fuel, hydrogen energy has been considered as an ideal energy source to deal with the growing energy crisis and environmental issues due to the advantages of high combustion value (285.8 kJ·mol-1) and zero carbon emission.1-3 Sunlight-driven photocatalytic water splitting for hydrogen production has been extensively investigated because it is low-cost and environment-friendly. To this end, the discovery of stable, efficient and cost-effective photocatalyst has become


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a priority.4-6 A vast number of materials has been explored as efficient photocatalysts over the last few decades. Among them, 2D nanosheets photocatalyst with appropriate band structure have arouse a great deal of research interest because of their high specific surface area, the unique structure and electronic properties. As a typical ultrathin 2D photocatalyst, SnNb2O6 with different thickness have been reported due to its superior photocatalytic activity. For instance, a typical SnNb2O6 nanoplates with a thickness of 28.1 nm was obtained by Hong et al. via solvothermal method.7 Liang et al. prepared a visible-light-activated SnNb2O6 nanosheets with a thickness of 1-4 nm.8 The layered sheet structure of SnNb2O6 was constructed by the two edge-sharing octahedral NbO6 units and Sn2+ ions that inserted between two octahedron-thick sheets. Moreover, relatively low valence band position endows the SnNb2O6 with the ability that respond to visible light region.9 Therefore, it has been extensively utilized in the degradation of organic pollutes, photocatalytic hydrogen production as well as direct CO2 photoreduction.10-13 Despite this, the photocatalytic activity of single SnNb2O6 nanosheet is still limited by the rapid recombination of photo-generated electrons and holes. Therefore, many strategies have been developed to further improve the photocatalytic performance of single photocatalyst over the last few decades, such as dye and quantum dots-sensitization,14-16 fabrication of heterojunction



structure, 17,18 and loading of cocatalysts.19,20 Recently, the research on quantum dots in photocatalysis and photoelectrocatalysis has gradually become a hot topic due to its better photostability, low-toxicity and tunable surface chemistry.21-24 Specially, carbon-based quantum dots are of great interest in the realm of catalysis, such as carbon quantum dots (CQDs),25,26 graphene quantum dots and carbon nitride quantum dots (CNQDs).27-30 Different from graphene quantum dots and CQDs, CNQDs exhibits a unique property because there exist abundant graphitic or pyridinic N atoms in the sp2 plane and amine groups (–NH or –NH2) on the terminating edges. Moreover, like N-doped graphene quantum dots, CNQDs could also serve as electron acceptors to accelerate charge transport.31-33 Therefore, CNQDs could be employed as an alternative catalyst in photocatalysis and electrocatalysis. Wang et al. successfully prepared g-C3N4 quantum dots by a thermal-chemical etching process and used as general energy-transfer components to enhance the photocatalytic activity of single-component bulk g-C3N4 and P25, which is ascribed to the up-conversion behavior of as-prepared CNQDs.34 Zhong and co-workers incorporated g-C3N4 quantum dots on graphene nanosheets. The as-prepared g-C3N4 quantum dots/graphene nanosheets exhibited a low overpotential and long-term durability for HER performance.35 To the best of our knowledge, no work was reported for the preparation of 0D/2D CNQDs/SnNb2O6 ultrathin


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nanosheets nanocomposite. It is expected that the intrinsic nature of CNQDs can increase the light-harvesting and charge migration of SnNb2O6 ultrathin nanosheets. In the present study, for the first time, CNQDs/SnNb2O6 ultrathin nanosheets nanocomposite was fabricated via a facile hydrothermal process. The up-conversion behavior of CNQDs was demonstrated by photoluminescent spectra when excitation with long wavelengths. It could also be validated by the hydrogen evolution experiments at long wavelength using a cut-off filter (λ > 600 nm). The sample loaded with 10 wt.% of CNQDs shows a photocatalytic H2 production of 11.2 umol·h-1·g-1 under the irradiation of light with wavelength greater than 600nm, which is four times higher than that of loading with 5 wt.% of CNQDs. while no H2 was detected on pristine CNQDs and SnNb2O6 nanosheets.

In

addition,

transient

photocurrent

response

and

electrochemical impedance spectra of CNQDs/SnNb2O6 photocatalyst suggest that CNQDs plays a crucial role in accelerating photocatalytic reaction.

Finally,

a

plausible

photocatalytic

mechanism

of

CNQDs/SnNb2O6 nanocomposite photocatalyst was proposed for enhancing photocatalytic H2 production. EXPERIMENTAL SECTION Materials. Urea, niobic oxide (Nb2O5) and potassium hydroxide (KOH) were purchased from Sigma-Aldrich. Sodium citrate, thiacetamide, and



stannous chloride (SnCl2·2H2O) were commercially supplied by Aladdin (Shanghai, China). All reagents were analytically grade and used without further purification. Synthesis of catalysts. The pure SnNb2O6 was prepared by a two-step hydrothermal method according to a literature procedure,36 as illustrated in Scheme 1. A suspension was obtained by dissolving 0.5 g of Nb2O5 and 3.36 g of KOH in 60 mL distilled water. The suspension was stirred for 30 min and then sealed to a Teflon-lined autoclave that was kept at 180 ◦C for 72 h. After natural cooling to the room temperature, Nb2O5·nH2O precursor solution was obtained by adjusting the pH value of suspension to 7.0 with HCl (2 M). Thereafter, 0.4244 g of SnCl2·2H2O added slowly to Nb2O5·nH2O solution and stirred for another 30 min and continued to adjust pH to 2.0 with HCl (2 M). The mixture then transferred to Teflon-lined autoclave and kept at 180 ◦C for 48 h. The yellow precipitate was collected by centrifugation and thoroughly washed with deionized water and ethanol several times and dried at 60 ◦C in vacuum for 12 h to obtain pure SnNb2O6. CNQDs was prepared through a hydrothermal route according to previous report with a little modification.37 Typically, 0.1 g of urea and 0.081 g of sodium citrate was homogeneously mixed and ground for 5 min in a mortar. The mixture was transferred into a Teflon-lined autoclave which is filled with deionized water to 80% volume of autoclave capacity


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(100 mL) and heated to 180 ◦C for 2 h in a drying oven. After cooling naturally, the obtained light-yellow solution was washed with ethanol and centrifugation at 12, 000 rpm for three times. The as-prepared sample was dialyzed in pure water with dialysis membrane for 24 h. g-C3N4 quantum dots was obtained by a freeze-drying process for the dialysis solution. Preparation of CNQDs/SnNb2O6 nanocomposite. Typically, 0.2 g of as-prepared SnNb2O6 photocatalysts was dispersed in 40 mL of distilled water and stirred for 30 min. a certain amount of CNQD was added to above suspension and ultrasound for 20 min under constant stirring. then the mixture suspension was transferred to a 100 mL Teflon-lined autoclave and heated to 180 ◦C for 4 h to ensure CNQDs were incorporated on the surface of SnNb2O6 nanosheet. After cooling to room temperature, the sample was centrifugated and washed with ethanol and deionized

water

for

several

times.

Finally,

CNQDs/SnNb2O6

nanocomposite was obtained after the sample dried at 80 ◦C for 24 h. The mass ratio of CNQDs was 0 wt.%, 5 wt.%, 10wt.%, 100 wt.%, respectively. They were denoted as SNO, CNS-5, CNS-10 and CNQDs, respectively.



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Scheme 1. Schematic illustration of the synthesis process of 0D/2D CNQDs/SnNb2O6 nanocomposite. Characterization. The crystallinity and phase of as-prepared samples was analyzed by powder X-ray diffraction (XRD) patterns (Bruker D8 Advance diffractometer, Germany) using a CuKα radiation source (λ=1.542 Å). The composition of the photocatalysts were acquired on an X-ray

photoelectron

spectrometer

(Thermo

ESCALAB

250Xi).

Field-emission scanning electron image (FESEM, Hitachi, Japan) was carried out to examine the morphology of the samples. Transmission electron microscopy and high-resolution TEM (HRTEM) was collected on a F20 S-TWIN TEM instrument, operated at 200 kV accelerating voltage (Tecnai G2 FEI, Co.). UV-vis diffuse reflectance spectra (DRS) was performed on a Shimadzu UV-2550 spectrum. Photoluminescence spectra (PL) were taken using a F4500 photoluminescence detector (Hitachi, Japan) at room temperature. Photocatalytic H2 production test. Photocatalytic hydrogen evolution


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over the photocatalyst was carried out using a gas closed circulation system and the 300 W Xenon lamp equipped with a cutoff filter (λ > 420 nm). Moreover, a cutoff filter (λ > 600 nm) was also used to investigate the photocatalytic performance of as-prepared samples based on the upconversion property of CNQDs. In a typical process, 0.05 g of photocatalyst powder was suspended by constant stirring in 200 mL of mixed aqueous solution containing 40 mL of methanol and 160 mL of water. As a comparison, some samples are loaded with 0.5wt.% Pt as a co-catalyst. Prior to illumination, the system was pumped to vacuum to remove any dissolved air and ensure the reaction system is under anaerobic conditions. The solution temperature of reaction system was kept at 5 ◦C by a water cooling system. The above solution was constantly stirred to keep the uniformity of the suspension under photocatalytic reaction. The content of H2 was analyzed by gas chromatography (GC-7900, CEAULIGHT, China, TCD, Nitrogen as a carrier gas and 5 Å molecular sieve column) at the given time intervals. Photoelectrochemical measurements. Spin coating method was adopted to prepare the working electrodes according to the previous reports.38,39 In a typical process, 0.1 g of as-prepared catalyst dispersed in 3 mL ethanol containing 0.01 g of PVP (K30, Mw = 40000) and 0.03 mL of oleic acid. The suspension gradually coated onto a clean fluorine-doped tin oxide (FTO) glass surface via a spin coater (MODEL



KW-4A, Shanghai), China) after the mixture suspension stirring for 2 h. Then prepared sample was then annealed in a muffle at 400 ◦C for 2 h to ensure a better electronic connection between the sample and FTO. Photocurrent measurement was carried out using the conventional three-electrode setup (Pt wire and Ag/AgCl electrode was used as the counter electrode and reference electrode, respectively) connected to an electrochemical station (CHI 852C, Shanghai Chenhua, China). 0.05 M Na2SO4 was used as the electrolyte solution and a 300 W xenon lamp (the light intensity is 47 mW/cm2) was used as a light source. Electrochemical impedance spectra (EIS) was conducted on three electrode quartz cell with 5 mM [Fe(CN)6]3−/[Fe(CN)6]4− solution at room temperature (CHI 760E, Shanghai Chenhua, China). RESULTS AND DISCUSSION The morphologies and nanostructure of pristine SNO and CNQDs/SNO composite catalyst were investigated using SEM, TEM and HRTEM images. As illustrated in Figure 1a, SNO presented a layer stacking structure with the irregular ultrathin nanosheet. The TEM image further confirmed the ultrathin flake structure of SNO (Figure 1b). The plate nanosheet structure of SNO can not only effectively improve the specific surface area, but also provide a better substrate for the deposition of CNQDs.40,41 Figure 1c displays the representative low-resolution TEM image of CNQDs/SNO composite. It can be seen that CNQDs (black dots)


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are inhomogeneous dispersed on the surface of SNO nanosheet. HRTEM image presented in Figure 1d depicts a distinctive lattice spacing of 0.28 nm, which correspond to the (600) plane of monoclinic SnNb2O6, another interplanar distance is approximately 0.34 nm, revealing the lattice plane of (002) plane of hexagonal g-C3N4.42,43 These results indicate that CNQDs/SNO composite photocatalyst were successfully prepared.

Figure 1. (a) SEM and (b) TEM of images SnNb2O6 nanosheet. (c) TEM and (d) HRTEM image of CNS-10. Figure 2 displays the X-ray diffraction patterns (XRD) of as-obtained CNQDs/SNO composite samples as well as the pristine CN and SNO samples. For pure CNQDs, two peaks can be observed at 2θ values of 13.1° and 27.1°, which can be assigned to an in-plane structural packing motif of tri-s-triazine for (100) crystal plane and stacking of conjugated ACS Paragon Plus Environment


aromatic rings for (002) crystal plane, respectively.44 No other impurity peaks were observed, suggesting that as-prepared CNQDs have high purity. The pristine SNO exhibits a monoclinic phase with characteristic diffraction peaks at 24.7 o, 29.0 o, 31.3 o, 34.1 o, 36.8 o, 51.0 o, 53.0 o, 54.5 o and 61.6 o, which correspond to (-111), (-311), (510), (202), (020), (222), (-113), (911) and (331) diffraction planes, respectively (JCPDS No. 84-1810). While no peaks of CNQDs was observed with the addition of CNQDs. This phenomenon may be ascribed to the low amount of CNQDs in the CNQDs/SNO composite, resulting in CNQDs were well-dispersed on the surface of SNO and the characteristic peaks of CNQDs are overlapped by the peaks of SNO. Similar findings are reported by other literature.45-47 Moreover, the peaks in CNQDs/SNO composites show no significant changes compared to the pure SNO, indicating that the deposition of CNQDs has little effect on the crystal structure of SNO.


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Figure 2. XRD patterns of CNQDs, SNO and CNQDs/SNO composites with different mass ratios of CNQDs. XPS measurement was used to investigate surface structure and composition of CNS-10. As shown in Figure 3a, the survey XPS spectrum shows that the existence of Sn, Nb, O, C and N elements. No other foreign element was detected. The C 1s spectrum could be deconvoluted into three peaks centered at 288.5, 286.1 and 284.8 eV. Among them, the binding energy peak at 286.1 eV are attributed to N-sp3 C and C=O bonds and the peak at 288.5 eV is ascribed to the sp2-hybridized carbon in N-containing aromatic ring (N-C=N). Whereas the peak at 284.8 eV is derived from sp2 C=C bonds.48 Three peaks are presented after fitting of N 1s spectra at around 400.8, 399.5 and 398.8 eV. These peaks can be regarded as the sp2 hybridized nitrogen involved in ACS Paragon Plus Environment


the tertiary nitrogen N (C)3 groups, triazine rings (C-N=C) and the free amino groups (N-H), respectively.49 For Sn 3d spectrum (Fig 3d), two major peaks can be observed at 494.6 and 486.1 eV, which is ascribed to the binding energy of Sn 3d5/2 and 3d3/2, respectively. Two prominent peaks for Nb 3d (Figure 3e) at 206.8 and 209.6 eV with a 2.8 eV spin-orbit splitting value is characteristic of Nb5+ species in the CNS-10. The O 1s spectrum shown in Figure 3f can be split into three peaks. The peak at 532.7 eV is assigned to the adsorbed water species, whereas the peaks at 531.6 and 530.1 eV can be ascribed to and surface hydroxyl groups and crystal lattice oxygen in the structure of SNO, respectively.50

Figure 3. XPS spectra of the CNS-10 sample. (a) the survey spectrum. (b) C 1s. (c) N 1s. (d) Sn 3d. (e) Nb 3d and (f) O 1s. Figure 4 shows the UV-vis diffuse spectra of CNQDs, SNO, and


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CNQDs/SNO composites. The SNO displays a sharp absorption edge of ∼580 nm, corresponding to the bandgap energy of 2.2 eV, which is close to the previous literature.51 Whereas the pristine CNQDs exhibits the absorption in the wavelength 200-800 nm, which indicates that CNQDs has a better photo-absorption ability in both UV and visible light region. It can be observed that the sensitization of SnNb2O6 with the CNQDs could increase the absorption range. Specially, the absorption in the visible light region is significantly extended when the quantum dot content is 10 wt.%. This is mainly due to the coupling of electrons and quantum effects of CNQDs. As a result, the as-prepared CNQDs/SNO composites could increase the utilization of solar light and improve the photocatalytic performance toward the hydrogen generation from water splitting.

Figure 4. UV-vis diffuse reflectance spectra of pure CNQD, SNO, and the CNQDs/SNO composites. ACS Paragon Plus Environment


Figure 5a shows the photoluminescence spectra of CNQDs under different excitation wavelengths. When the excitation wavelength increases from 340 to 400 nm, the PL peak moves toward a longer wavelength. However, the emission peak decreases rapidly when the excitation wavelength is 420 nm. The same phenomenon has been reported in the previous literature.34 The intrinsic luminescence of CNQDs may be caused by the π–π* transition in the aromatic structure. In addition, the upconverted photoluminescence spectra of CNQDs was also investigated by using different excitation wavelengths, as shown in Figure 5b. It was observed that when varied from 720 to 840 nm, CNQDs shows the emission in the range of 350 to 650 nm, which is occupied most of the visible light range. This indicates that the as-prepared CNQDs have obvious up-conversion property, which could be used as energy transfer component to convert long wavelength light to visible light and thus enhance the solar energy harvesting in CNQDs/SNO photocatalytic system. The upconversion behavior of CNQDs is mainly caused by the multiphoton excitation process.52


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Figure 5. (a) PL spectra of the CNQDs at different excitation wavelengths. (b) the upconversion PL spectra of the CNQDs. The photocatalytic performance of various photocatalysts for hydrogen production under visible light irradiation was detected, as shown in Figure 6. No H2 was detected for the pristine SNO under visible light irradiation (λ >420 nm) within 5 h. This may be caused by the fast recombination of photo-induced electrons and holes in SNO nanosheet. To verify this hypothesis, 0.5 wt.% Pt was loaded as a cocatalyst on the SNO nanosheet. It can be seen that the photocatalytic H2 production from water splitting was significantly improved after the loading of Pt, achieving a value of 90 µmol·g-1 within 5 h under visible light irradiation (Figure 5a). Moreover, the pristine CNQDs did not show any photocatalytic H2 generation under the same conditions. Despite this, photocatalytic H2 production of CNQDs/SNO composite exhibits an obvious improvement with the addition of CNQDs. The amount of H2 achieved to 38 µmol g-1 for CNS-5, whereas H2 was greatly enhance ACS Paragon Plus Environment


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when the content of CNQDs achieved to 10 wt.% (105 µmol g-1), which is even higher than the Pt/SNO sample (90 µmol g-1). Figure 6b shows the hydrogen production rate for various samples. Note that the CNS-10 exhibits the highest hydrogen production rate in contrast to other species, which is about 2.6-fold and 1.4-fold higher than the CNS-5 and Pt/SNO, respectively. To

further

investigate

the

up-conversion effect

of

CNQDs,

photocatalytic H2 for the as-prepared sample under near-infrared light (λ > 600 nm) was carried out, as presented in Figure 6c. No H2 produced for SNO and Pt/SNO, while H2 produced rate was 2.8 µmol g-1 h-1 for CNS-5 and the amount increased to 11.2 µmol g-1 h-1 for CNS-10, which is four times higher than that of CNS-5. The result suggests that the CNQDs could be used as up-conversion function material to enhance the photo-absorption of photocatalyst and thus promoting the photocatalytic H2 activity from water splitting. The stability of CNS-10 sample was also studied, and the result was presented in Figure 6d. The CNS-10 sample shows no obvious deactivation after four cycles, suggesting that CNS-10 is stable during the photocatalytic reaction.


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Figure 6. (a) The photocatalytic H2 production activity of various samples. (b) the rate of H2 evolution over different samples under visible light irradiation (λ>420 nm). (c) the long wavelength light irradiation (λ >600 nm). (d) recyclability study of CNS-10. Error bars represent mean ± s.d. of at least three independent experiments. Photocurrent response and electrochemical impedance spectra (EIS) were used to understand the migration and separation of photoinduced carriers in photocatalyst under light irradiation. Figure 7a shows photocurrent responses of SNO and CNS-10 composite. The photocurrent density of CNS-10 is significantly higher than the pure SNO, which is about 2.5-fold higher than that of SNO, indicating a higher ability of charge separation is achieved for CNS-10. Figure 7b exhibits the EIS ACS Paragon Plus Environment


results of SNO and CNS-10 samples. The smaller arc radius on the EIS Nyquist plot of CNS-10 photoelectrode under light irradiation suggests that effective separation of photogenerated electron-hole pairs and a faster interfacial charge transfer was occurred compared to the pure SNO ultrathin nanosheets. As a result, an enhanced photocatalytic H2 performance was achieved. It could be concluded that the introduction of CNQDs is beneficial to accelerate the electron transfer, which is similar to carbon quantum dots reported by other researchers.53-55

Figure 7. (a) Transient photocurrent response and (b) Nyquist plots of SnNb2O6 and CNS-10 samples. On the basis of the discussion above, we proposed a possible photocatalytic H2 from water splitting for CNQDs/SNO composite, as shown in Scheme 2. Generally, the pristine SNO ultrathin nanosheet could be generated under visible light irradiation (λ>420 nm) and produce electrons and holes owing to its suitable bandgap. CNQDs on the surface of ultrathin SNO nanosheet can serve as an electron acceptor and improve


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the transfer efficiency of photo-generated carriers. The electrons on the conduction of SNO rapidly migrate to the surface of quantum dots and thereby achieving the photocatalytic H2 production, where holes on the valence band would be captured by methanol and oxidation products was formed. When the incident light wavelength is greater than 600 nm, the pristine SNO could not be generated owing to its wide band gap. However, CNQDs can convert long wavelength light (λ >600 nm) into visible light to excite SNO to generate photogenerated carriers due to upconversion property of CNQDs. Therefore, CNQDs could not only be served as an electron acceptor to accelerate electronic transfer, but also increase the utilization of solar light. As a result, an enhanced photocatalytic H2 from water splitting was achieved for CNQDs/SNO composite.



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Scheme 2. Photocatalytic H2 production mechanism over CNQDs/SNO nanocomposite under visible light irradiation. CONCLUSIONS In brief, g-C3N4 quantum dots modified SnNb2O6 ultrathin nanosheet photocatalyst was fabricated via a facile hydrothermal method. The photocatalytic

water

splitting

for

hydrogen

activity

on

the

CNQDs/SnNb2O6 catalysts were conducted under visible light and NIR light irradiation. With the addition of CNQDs, the photocatalytic performance of H2 production was significantly improved in contrast to the pristine SnNb2O6. It should be noted that photocatalytic H2 activity is still present under the long wavelength (λ > 600 nm) irradiation. On one hand, the upconversion effect of CNQDs could extend the absorption of the photocatalyst. On the other hand, the existence of CNQDs could be served as an effective collector of charge carriers thus improve photocatalytic H2 generation. The present work provides a way to improve photocatalytic activity by not only increasing the utilization of sunlight, but also accelerating the electron transfer of the photocatalyst. AUTHOR INFORMATION Corresponding Author *E-mail: [email protected]. Notes The authors declare no competing financial interest.


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ACKNOWLEDGMENTS The authors gratefully acknowledge the support from the National Natural Science Foundation of China (21477050 and 21522603), the Excellent

Youth

Foundation

of

Jiangsu

Scientiﬁc

Committee

(BK20140011), the Program for New Century Excellent Talents in University (NCET-13-0835), the Henry Fok Education Foundation (141068) and the Innovation/Entrepreneurship Program of Jiangsu Province (Surencaiban [2016] 32).

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0D/2D carbon nitride quantum dots/ SnNb2O6 ultrathin nanosheets with enhanced photocatalytic hydrogen production was fabricated. 338x190mm (150 x 150 DPI)


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SnNb2O6 Ultrathin

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