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Energy Material Advances / 2022 / Article

Research Article | Open Access

Volume 2022 |Article ID 9897860 | https://doi.org/10.34133/2022/9897860

Abraham Adenle, Ming Shi, Xiaoping Tao, Yue Zhao, Bin Zeng, Na Ta, Rengui Li, "Crystal Facet-Dependent Intrinsic Charge Separation on Well-Defined Bi4TaO8Cl Nanoplate for Efficient Photocatalytic Water Oxidation", Energy Material Advances, vol. 2022, Article ID 9897860, 9 pages, 2022. https://doi.org/10.34133/2022/9897860

Crystal Facet-Dependent Intrinsic Charge Separation on Well-Defined Bi4TaO8Cl Nanoplate for Efficient Photocatalytic Water Oxidation

Received28 Apr 2022
Accepted25 May 2022
Published17 Jun 2022

Abstract

The development of photocatalysts with wide spectral absorption and high charge separation efficiency has always been a pursued objective for photocatalytic solar energy conversion. Herein, we reported a wide-range visible-light-active Bi4TaO8Cl (BTOC) single crystal nanoplate with dominating {110} and {001} facets for enhancing the intrinsic charge separation efficiency. Insitu selective photodeposition of metals and metal oxides provides evidences of photogenerated electrons and holes spatially separated on {110} and {001} coexposed facets of BTOC, respectively. The intrinsic charge separation efficiency was demonstrated to be closely dependent on the crystal facets, which can be modulated by tuning the coexposed crystal facet ratio. Further surface modification of BTOC with suitable dual cocatalyst Ag and RuOx enables remarkable improvement of charge separation efficiency and photocatalytic water oxidation performance. Investigation by comparison between well-defined BTOC nanoplate and BTOC nanoparticles confirmed the significance of coexposed crystal facets for efficient spatial charge separation and the blocking of reverse reaction from Fe2+ to Fe3+ ions during water oxidation reaction, indicating that rational modulation of exposed crystal facets is significant for controlling the intrinsic charge separation efficiency on Bi4TaO8Cl photocatalyst for efficient photocatalytic water splitting.

1. Introduction

Photocatalytic water splitting for converting solar energy into clean and sustainable hydrogen energy is a promising approach to solve energy and environmental problems, while efficient photogenerated charge separation on a semiconductor photocatalyst is the key of the heterogeneous photocatalysis process [15]. As it is well known, surface atomic arrangement and coordination of semiconductors significantly affect the physicochemical properties and photogenerated charge separation [6, 7]. Therefore, rational regulation of the exposed crystal facets and surface atomic configurations of semiconductor-based photocatalysts by precisely optimizing the preparation process is essential for modulating the intrinsic charge separation properties [811]. Recently, the strategy for enhancing charge separation is focused on spatial charge separation between coexposed anisotropic facets of a low symmetry single crystal semiconductor [1218]. Realizing spatial charge separation on photocatalysts is dependent on the adopted preparation processes for the construction of crystal facets with dissimilar surface work function [19, 20]. The crystal facet-dependent charge separations have been reported on several photocatalysts, such as BiVO4, TiO2, BiOCl, SrTiO3, BaTaON, and NaTaO3 [2126]. Nevertheless, exploring wide-range visible-light-active photocatalysts with excellent charge separation properties and deepening understandings of the relationship between spatial charge separation and coexposed crystal facets are needed for further enhancing intrinsic charge separation efficiency and promoting the development of photocatalysis.

Silleń-Aurivillius perovskite (Bi4MO8X) compounds with narrow band gap are promising for solar water splitting [2731]. More importantly, their layered structure characteristics are beneficial for constructing anisotropic facets with low symmetry by precisely regulating the preparation procedures [32]. Bismuth tantalum oxychloride (Bi4TaO8Cl) as a typical example was recently reported for the preparation of {001} facet-dominated orthorhombic nanoplates [33], and the {001} facets are considered to be the photoactive surface [34]. In addition, Bi4TaO8X was also recently reported with improved photocatalytic CO2 reduction activity due to the surface modification by Ag nanoparticles [35]. Additionally, photoinduced surface modification by generating reactive species on the Bi4TaO8Cl surface was also reported [36]. Despite most the of literatures having demonstrated improved photocatalytic activities on Bi4TaO8Cl through surface modification [37], or loading of - suitable cocatalyst [38], the relationship between the intrinsic photoreactivity and the exposed facets is still unclear, and there is a lack of in-depth exploration about the crystal facet-dependent charge separation properties of Bi4TaO8Cl.

Herein, aiming to explore the crystal facet-dependent photoreactivity and modulate the intrinsic charge separation through regulation of highly exposed facets, Bi4TaO8Cl (BTOC) was chosen as a visible-light-active photocatalyst for water oxidation. Well-defined BTOC nanoplates with exposed {110} side facets and {001} top facets were synthesized using a facile flux method. The BTOC nanoplate displays the capacity of spatial charge separation proven by in situ photochemical deposition, where photogenerated electrons and holes are selectively accumulated on the {110} facets and {001} facets, respectively. The BTOC-0.8 displays a higher charge separation efficiency and AQE for photocatalytic O2 evolution than BTOC-0.5, BTOC-2.1, and BTOC-2.5, which may be due to the modulation of the coexposed crystal facet ratio. Furthermore, the charge separation efficiency and photocatalytic activity of BTOC-0.8 were further improved by loading dual cocatalysts Ag and RuOx, and the reverse oxidation of Fe2+ to Fe3+ ions was also blocked owing to spatial charge separation between coexposed facets.

2. Materials and Methods

2.1. Chemicals

Bismuth oxide (Bi2O3) with 99.99% purity was purchased from Aladdin, BiOCl (99.99%) from Sigma-Aldrich, and Ta2O5 (99.99%) from Ameresco Chemical, and NaCl (99.5%) and KCl (99.5%) were purchased from Sinopharm Chemical. All chemicals used were of analytical grade and were used without further purification unless otherwise stated.

2.2. Synthesis of Samples

BTOC well-defined photocatalyst crystal samples, BTOC-0.5, BTOC-0.8, BTOC-2.1, and BTOC-2.5, were prepared using flux method. In a typical synthesis, sample BTOC-0.5 was prepared by weighing stoichiometric ratios of Bi2O3, BiOCl, and Ta2O5 in the ratio of 5 : 4 : 2 in mmol with the eutectic mixture of NaCl : KCl (10 mmol : 10 mmol) as flux agents; the mixture was thoroughly mixed using mortar and pestle. Thereafter, the obtained mixture was transferred into a high-temperature stable evacuated silica crucible and calcined at 973 K for 3 h in a temperature-programed oven. Afterward, the obtained cooled yellow product was washed several times with deionized water and dried in the oven at 353 K overnight. Likewise, sample BTOC-0.8 was prepared by weighing stoichiometric ratios of Bi2O3, BiOCl, and Ta2O5 (5 : 4 : 2 in mmol) with eutectic mixture of NaCl and KCl (36 mmol : 36 mmol) of the precursor as flux agents and following suit. Similarly, samples BTOC-2.1 and BTOC-2.5 were prepared using a similar preparation process, except that the precursor concentration was adjusted. Samples BTOC-2.1 and BTOC-2.5 were prepared by weighing stoichiometric ratios of Bi2O3, BiOCl, and Ta2O5 (2 : 1.5 : 0.8 in mmol) and Bi2O3, BiOCl, and Ta2O5 (1.5 : 1 : 0.5 in mmol) with eutectic mixture of NaCl and KCl (1 : 1) as flux agents, respectively. The precursors were thoroughly mixed together using mortar and pestle for each sample; thereafter, the obtained mixture was transferred into a high-temperature stable evacuated silica crucible and calcined at 1023 K for 3 h in a temperature-programed oven to obtain samples BTOC-2.1 and BTOC-2.5. The obtained cooled yellow powder was washed several times with deionized water and dried in the oven at 353 K.

2.3. Characterizations

The as-prepared BTOC sample crystal structure was characterized using scanning electron microscopy (SEM, Quanta 200 FEG, FEI) and high-resolution transmission electron microscopy (HRTEM, JEM-F200). X-ray diffraction (XRD) was recorded on Rigaku D/Max-2500/PCXRD, and UV-visible (UV-vis) diffuse reflectance spectra were measured on a UV-vis spectrophotometer (JASCO V-550). Transient photocurrent response and electrochemical impedance spectroscopy were measured using an electrochemical workstation and VersaStudio CV (CHI-760D, Chenhua Instruments Co., Ltd.). Mott-Schottky measurements were carried out on a Princeton Applied Research PARSTAT 2273, and the frequency and amplitude of AC potential used were 1 kHz and 100 mV, respectively.

3. Results

3.1. Structural and Morphological Characterization

Bismuth tantalum oxychloride Bi4TaO8Cl (BTOC) was prepared using flux preparation method. Firstly, the precursor ratio and the synthesis temperature were extensively studied to determine the optimal synthesis conditions. For BTOC samples prepared using different ratios of Bi2O3, BiOCl, and Ta2O5, the X-ray diffraction (XRD) results show no significant difference and the diffraction peaks of all samples were indexed to Bi4TaO8Cl with orthorhombic phase symmetry, and the UV-visible absorption patterns also exhibit similar optical properties (Figure S1). In addition, the SEM images shows that all samples are nanoplate-like in shape except for thickness differences that affect the proportion of exposed facets (Figure S2). To investigate the validity of precursor ratio regulation, photocatalytic water oxidation was conducted on the BTOC samples using Fe(NO3)3 as electron scavengers (Figure S3). It was observed that photocatalytic water oxidation activity varied significantly with the precursor ratio, and the BTOC prepared using a precursor ratio of 5 : 4 : 2 for Bi2O3, BiOCl, and Ta2O5, respectively, shows the highest photocatalytic activity, showing that acurate precursor concentration plays an important role in preparation of BTOC photocatalyst. Furthermore, different BTOC samples were prepared using the same precursor ratio of 5 : 4 : 2 for Bi2O3 : BiOCl : Ta2O5, respectively, under different temperatures. The XRD peak intensity of the as-prepared samples increases gradually with the increase of temperature, indicating the enhancement of crystallinity (Figure S4a). In addition, UV-visible absorption spectra display similar absorption band edges with exception of the sample at 600°C (Figure S4b). SEM images exhibit that the apparent shape of the as-prepared BTOC changes from regular nanoplates to nanoparticles over temperatures ranging from 900°C to 600°C (Figure S5). Therefore, the flux temperature has significant effect on the growth of BTOC nanoplates crystal. Similarly, the photocatalytic water oxidation activity was conducted, and the BTOC synthesized at 700°C show the highest photocatalytic O2 evolution activity (Figure S6).

In order to further explore the reasons for the differences in photoreactivity of different BTOC nanoplates, several typical BTOC samples were selected for a more detailed characterization and analysis. For convenient identification, these samples are named BTOC-0.5, BTOC-0.8, BTOC-2.1, and BTOC-2.5, according to the diffraction peak intensity ratios of (004) and (220) crystal facets that reflect the modulation of the coexposed facet ratio to some extent. Figure 1(a) shows that there is no obvious difference in the XRD patterns, and they were indexed to the BTOC with orthorhombic phase symmetry. SEM images of BTOC-0.5, BTOC-0.8, BTOC-2.1, and BTOC-2.5 show a square nanoplate-like shape with difference in the thickness (Figure 1(b), Figure S7), which further shows the diversity in the exposed ratio of the top and lateral surfaces. To identify the corresponding exposed facets, high-resolution transmission electron microscopy (HRTEM) analysis was performed on the BTOC-0.8 (Figure 1(c)). Selected-area electron diffraction (SAED) pattern gives a diffraction spot with identified (220) and (200) planes of orthorhombic BTOC (Figure 1(d)). HRTEM image conducted on the top facet shows the lattice fringe spacing of 0.387 nm and 0.274 nm indexes to (110) and (020) planes of BTOC, respectively (Figure 1(e), Figure S8). Therefore, given the orthorhombic BTOC phase symmetry, the highly exposed facets of the as-prepared BTOC samples can be recognized as {001} top facets and {110} side facets; the difference of these samples is the variation in the exposed facet ratio.

3.2. Optical Properties

Figure 2(a) shows the arrangement and coordination of Bi, Ta, O, and Cl atoms along the (001) top facet and (110) side facet. UV-vis diffuse reflectance spectra (DRS) and the Mott-Schottky measurement were conducted to investigate the optical absorption band structure. As shown in Figure 2(b), BTOC-0.5, BTOC-0.8 BTOC-2.1, and BTOC-2.5 display a comparable light absorption edge except that BTOC-2.1 and BTOC-2.5 exhibit higher extinction coefficient in the short wavelength range than BTOC-0.5 and BTOC-0.8. According to the plots of (αhv)1/2 versus photon energy (hv), the band gap energies (Eg) of BTOC-0.5, BTOC-0.8, BTOC-2.1, and BTOC-2.5 were determined to be 2.40 eV. The positive slope of the Mott-Schottky plots reveals the n-type characteristics while the flat band potentials were determined to be between -0.10 V and -0.17 V (vs. RHE) (Figure 2(c)). Combining these results, the electronic band structures of BTOC-0.5, BTOC-0.8, BTOC-2.1, and BTOC-2.5 are shown in Figure 2(d), and the band positions are comparable.

3.3. Photogenerated Charge Distribution

The photogenerated charge distribution on the coexposed {001} and {110} facets of the as-prepared BTOC samples was further explored by in situ photochemical deposition of metal oxides and metals [22]. As depicted in Figure 3, after photooxidation reactions taking Mn2+ and Pb2+ ions as precursors and IO3- ion as electron scavenger, MnOx and PbO2 particles were found mainly deposited on the top {001} surface, showing that photogenerated holes are specifically selectively accumulated on the {001} facets (Figures 3(b) and 3(c), Figure S9). Also, after photoreduction reactions of metals in the presence of methanol (CH3OH) as the hole scavenger, it is revealed that Au, Ag, and Pd particles were specifically deposited on the {110} lateral facets and not on the {001} top facets, suggesting that {110} facets are more favorable for accumulating photogenerated electrons on the BTOC (Figures 3(d)–3(f), Figure S9). To further corroborate the selectively spatial separation of electrons and holes between the coexposed {110} and {001} facets, simultaneous photodeposition of Au and MnOx was conducted. After photodeposition reaction, Au and MnOx particles were found selectively aggregated on the {110} and {001} facets, respectively, showing precisely that, spatial separation of photogenerated electrons and holes on the coexposed facets of BTOC was achieved (Figure S9). As schematically demonstrated in Figure 3(g), photogenerated electrons and holes are spatially separated on the {110} and {001} coexposed facets of BTOC nanoplates, respectively. These results confirm that precisely controlled exposure of anisotropic crystal facets could achieve effective spatial charge separation by properly optimizing the synthesis parameters during BTOC sample preparation.

3.4. Charge Separation Efficiency

To investigate the intrinsic charge separation efficiency of BTOC-0.5, BTOC-0.8, BTOC-2.1, and BTOC-2.5 samples, photocatalytic reaction was conducted in the presence of CH3OH as hole scavengers and Fe3+ ions as electron acceptors under visible light (). Noticeably, BTOC-0.8 displays much higher charge separation efficiency than BTOC-0.5, BTOC-2.1, and BTOC-2.5 (Figure 4(a), Figure S10), although electrons and holes are spatially separated onto different coexposed facets for all samples, indicating that charge separation and migration from the bulk to the surface in BTOC are largely affected by the difference in the coexposed facet ratio. Furthermore, photocatalytic water oxidation and the corresponding apparent quantum efficiency (AQE) tests were conduted to explore the effect of charge separation property on photocatalytic water oxidation performance. The results show that BTOC-0.8 still displays the higher photocatalytic O2 evolution activity than other samples regardless of whether AgNO3 and Fe(NO3)3 are electron acceptors (Figure 4(b), Figure S11) and achieves the highest AQE for photocatalytic water oxidation (Figure S11). This is consistent with the results of charge separation efficiency, indicating that the variation of photocatalytic activity between BTOC samples mainly originates from the difference of charge separation properties. Moreover, photoelectrochemical (PEC) measurement was also performed to corroborate the above results, and the BTOC-0.8 shows a markedly higher photocurrent density than others, a result comparable with the charge separation efficiency trend (Figure 4(c)). Also, electrochemical impedance spectroscopy (EIS) analysis was adopted to explore the charge transfer process (Figure 4(d), Table S1). It is shown that the BTOC-0.8 possess the smaller charge transfer resistance indicating faster charge separation and transfer. The above results specifically confirm that charge separation is readily available on these samples, but the difference in charge carrier dynamics owing to the different coexposed facet ratio led to the observed significant difference in the photocatalytic performance between the as-prepared samples.

3.5. Photocatalytic Activity

As the reduction and oxidation cocatalysts has been widely demonstrated to promote surface reaction, we further optimized the photocatalytic activity by loading appropriate cocatalysts. BTOC is modified by means of in situ photodeposition of Ag and RuOx as a single and or dual cocatalyst, and the photocatalytic water oxidation performance was tested in the present of Fe(NO3)3 as electron scavengers. As shown in Figure 5(a), the cocatalyst-modified BTOC-0.8 show higher photocatalytic activity regardless of single or dual cocatalyst modification than the pristine BTOC-0.8, especially the sample loaded with a dual cocatalyst (Ag/RuOx/BTOC-0.8); the photocatalytic activity almost doubled. In addition, (Fe,Ru)Ox as dual cocatalyst was also demonstrated to enhance the photocatalytic activity as shown in Figure S12 [39]. Moreover, the improved surface reaction in turn further promotes the enhancement of charge separation efficiency (Figure 5(b)), which indicates that the loading of the cocatalyst significantly accelerates the extraction and utilization of photogenerated charges. Finally, the AQE of photocatalytic oxygen evolution improved to ~10% at 420 nm (Figure 5(b)). As it has been demonstrated previously that achieving spatial charge separation between coexposed facets on well-define particulate photocatalysts could inhibit the reverse oxidation reaction from Fe2+ to Fe3+ due to the existence of coulomb repulsion force between the Fe2+ ions and positively charged facets [40, 41], time-dependent photocatalytic water oxidation was conducted in the presence of the Fe3+/Fe2+ shuttle to corroborate the effect of spatial charge separation on blocking of reverse reaction. Notably, Fe2+ ions formed during the photocatalytic water oxidation could reach the theoretical value of Fe3+ ions in the original solution, regardless of the initial concentration of Fe3+ (Figure 5(c), Figure S13), and the cocatalysts promoted the water oxidation reaction rate and accelerated the consumption of Fe3+ ions (Figure 5(d)). This illustrates that the oxidation reverse reaction, from Fe2+ to Fe3+, was completely blocked by the achievement of spatial charge separation, which was also observed in BTOC-2.1 (Figure S14). In order to further confirm the significant role of spatial charge separation between coexposed facets in improving photocatalytic water oxidation activity, BTOC nanoparticle was prepared under the same reaction conditions and explored for photocatalytic water oxidations (Figure S15S16). The results clearly show that BTOC nanoparticles display a very poor photocatalytic activity compared to the well-defined BTOC nanoplates, indicating that the spatial charge separation within BTOC nanocrystals plays a substantial role on the intrinsic charge separation efficiency and photocatalytic performance (Figure S17).

4. Discussion

In summary, we have synthesized well-defined Bi4TaO8Cl (BTOC) nanoplates with {110} and {001} dominant facets as a visible-light-active semiconductor. We demonstrated that the BTOC nanoplates possess the capacity of spatial charge separation, where photogenerated electrons and holes prefer to accumulate on the {110} facets and {001} facets, respectively. The intrinsic charge separation efficiency was demonstrated to be closely dependent on the crystal facets, which can be modulated by tuning the coexposed crystal facet ratio. The BTOC-0.8 displays a significant high charge separation efficiency and AQE for photocatalytic water oxidation, owing to the modulation of the coexposed crystal facet ratio. The photocatalytic water oxidation activity was further improved by loading dual cocatalysts Ag and RuOx, and the oxidation reverse reaction of Fe2+ to Fe3+ ions was totally blocked owing to spatial charge separation between coexposed facets. Our work unravels the crystal facet-dependent intrinsic photoreactivity, which provides a feasible strategy to fabricate semiconductor-based photocatalyst for solar energy conversion.

Data Availability

All data presented in the paper and the supporting information are available from the corresponding author upon reasonable request.

Conflicts of Interest

The authors declare no conflict of interest.

Authors’ Contributions

R.L. conceived the idea and revised the manuscript. A.A. and M.S. designed and performed most of the experiments and data analysis. X.T., Y.Z., and B.Z. contributed to the photocatalysis test and analysis. N.T. contributed to the HRTEM analysis. All authors discussed the results and contributed to the manuscript. Abraham Adenle and Ming Shi contributed equally to this work.

Acknowledgments

The work was supported by the National Key Research and Development Program of China (2021YFA1502300), conducted by the Fundamental Research Center of Artificial Photosynthesis (FReCAP), and financially supported by the National Natural Science Foundation of China (22088102). R.L. thanks the support from the National Natural Science Foundation of China (22090033) and the Youth Innovation Promotion Association of the Chinese Academy of Sciences. A.A. gratefully acknowledges the CAS-TWAS Presidential fellowship.

Supplementary Materials

Figures S1–S17 and Tables S1 show the SEM, XRD, UV-vis absorption spectra, photocatalytic activity results, HRTEM, and SAED patterns. (Supplementary Materials). (Supplementary Materials)

References

  1. Z. Wang, Y. Luo, T. Hisatomi et al., “Sequential cocatalyst decoration on BaTaO2N towards highly-active Z-scheme water splitting,” Nature Communications, vol. 12, no. 1, p. 1005, 2021. View at: Publisher Site | Google Scholar
  2. Q. Wang, T. Hisatomi, Q. Jia et al., “Scalable water splitting on particulate photocatalyst sheets with a solar-to-hydrogen energy conversion efficiency exceeding 1%,” Nature Materials, vol. 15, no. 6, pp. 611–615, 2016. View at: Publisher Site | Google Scholar
  3. D. Wang, R. Li, J. Zhu et al., “Photocatalytic water oxidation on BiVO4 with the electrocatalyst as an oxidation cocatalyst: essential relations between electrocatalyst and photocatalyst,” The Journal of Physical Chemistry C, vol. 116, no. 8, pp. 5082–5089, 2012. View at: Publisher Site | Google Scholar
  4. L. Liao, Q. Zhang, Z. Su et al., “Efficient solar water-splitting using a nanocrystalline CoO photocatalyst,” Nature Nanotechnology, vol. 9, no. 1, pp. 69–73, 2014. View at: Publisher Site | Google Scholar
  5. N. Li, Y. Jiang, X. Wang et al., “Efficient charge separation and transfer of a TaON/BiVO4 heterojunction for photoelectrochemical water splitting,” RSC Advances, vol. 11, no. 22, pp. 13269–13273, 2021. View at: Publisher Site | Google Scholar
  6. A. J. Cowan, W. Leng, P. R. Barnes, D. R. Klug, and J. R. Durrant, “Charge carrier separation in nanostructured TiO2 photoelectrodes for water splitting,” Physical Chemistry Chemical Physics, vol. 15, no. 22, pp. 8772–8778, 2013. View at: Publisher Site | Google Scholar
  7. H. Wang, P. Amsalem, G. Heimel, I. Salzmann, N. Koch, and M. Oehzelt, “Band-bending in organic semiconductors: the role of alkali-halide interlayers,” Advanced Materials, vol. 26, no. 6, pp. 925–930, 2014. View at: Publisher Site | Google Scholar
  8. L. Ferrighi, G. Fazio, and C. D. Valentin, “Charge Carriers Separation at the Graphene/(101) Anatase TiO2Interface,” Advanced Materials Interfaces, vol. 3, no. 6, article 1500624, 2016. View at: Publisher Site | Google Scholar
  9. J. Ge, X. Ding, D. Jiang, L. Zhang, and P. Du, “Efficient improved charge separation of FeP decorated worm-like nanoporous BiVO4 photoanodes for solar-driven water splitting,” Catalysis Letters, vol. 151, no. 5, pp. 1231–1238, 2021. View at: Publisher Site | Google Scholar
  10. W. Gao, J. Lu, S. Zhang et al., “Suppressing photoinduced charge recombination via the Lorentz force in a photocatalytic system,” Advancement of Science, vol. 6, no. 18, article 1901244, 2019. View at: Publisher Site | Google Scholar
  11. R. Vinoth, P. Karthik, C. Muthamizhchelvan, B. Neppolian, and M. Ashokkumar, “Carrier separation and charge transport characteristics of reduced graphene oxide supported visible-light active photocatalysts,” Physical Chemistry Chemical Physics, vol. 18, no. 7, pp. 5179–5191, 2016. View at: Publisher Site | Google Scholar
  12. M. Costa, G. Costa, A. Lima et al., “Investigation of charge recombination lifetime in γ-WO3 films modified with Ag0 and Pt0 nanoparticles and its influence on photocurrent density,” Ionics, vol. 24, no. 10, pp. 3291–3297, 2018. View at: Publisher Site | Google Scholar
  13. G. Liu, Y. Zhu, Q. Yan et al., “Tuning electron transfer by crystal facet engineering of BiVO4 for boosting visible-light driven photocatalytic reduction of bromate,” Science of The Total Environment, vol. 762, article 143086, 2021. View at: Publisher Site | Google Scholar
  14. X. Wang, D. Liao, H. Yu, and J. Yu, “Highly efficient BiVO4 single-crystal photocatalyst with selective Ag2O-Ag modification: orientation transport, rapid interfacial transfer and catalytic reaction,” Dalton Transactions, vol. 47, no. 18, pp. 6370–6377, 2018. View at: Publisher Site | Google Scholar
  15. D. Wang, H. Jiang, X. Zong et al., “Crystal facet dependence of water oxidation on BiVO4 sheets under visible light irradiation,” Chemistry - A European Journal, vol. 17, no. 4, pp. 1275–1282, 2011. View at: Publisher Site | Google Scholar
  16. C. W. Kim, Y. S. Son, M. J. Kang, D. Y. Kim, and Y. S. Kang, “(040)-crystal facet engineering of BiVO4 plate photoanodes for solar fuel production,” Advanced Energy Materials, vol. 6, no. 4, article 1501754, 2016. View at: Publisher Site | Google Scholar
  17. M. Shi, G. Li, J. Li et al., “Intrinsic facet-dependent reactivity of well-defined BiOBr nanosheets on photocatalytic water splitting,” Angewandte Chemie, vol. 132, no. 16, pp. 6652–6657, 2020. View at: Publisher Site | Google Scholar
  18. Y. Zhao, R. Li, L. Mu, and C. Li, “Significance of crystal morphology controlling in semiconductor-based photocatalysis: a case study on BiVO4 photocatalyst,” Crystal Growth & Design, vol. 17, no. 6, pp. 2923–2928, 2017. View at: Publisher Site | Google Scholar
  19. S. Sato, K. Kataoka, R. Jinnouchi et al., “Band bending and dipole effect at interface of metal-nanoparticles and TiO2 directly observed by angular-resolved hard X-ray photoemission spectroscopy,” Physical Chemistry Chemical Physics, vol. 20, no. 16, pp. 11342–11346, 2018. View at: Publisher Site | Google Scholar
  20. Q. Zeng, X. Wang, X. Xie et al., “Band bending of TiO2 induced by O-xylene and acetaldehyde adsorption and its effect on the generation of active radicals,” Journal of Colloid and Interface Science, vol. 572, pp. 374–383, 2020. View at: Publisher Site | Google Scholar
  21. R. Li, F. Zhang, D. Wang et al., “Spatial separation of photogenerated electrons and holes among {010} and {110} crystal facets of BiVO4,” Nature Communications, vol. 4, no. 1, p. 1432, 2013. View at: Publisher Site | Google Scholar
  22. Z. Zheng, B. Huang, J. Lu, X. Qin, X. Zhang, and Y. Dai, “Hierarchical TiO2 microspheres: synergetic effect of {001} and {101} facets for enhanced photocatalytic activity,” Chemistry - A European Journal, vol. 17, no. 52, pp. 15032–15038, 2011. View at: Publisher Site | Google Scholar
  23. M. Li, S. Yu, H. Huang et al., “Unprecedented eighteen-faceted BiOCl with a ternary facet junction boosting cascade charge flow and photo-redox,” Angewandte Chemie International Edition, vol. 58, no. 28, pp. 9517–9521, 2019. View at: Publisher Site | Google Scholar
  24. L. Mu, B. Zeng, X. Tao, Y. Zhao, and C. Li, “Unusual charge distribution on the facet of a SrTiO3 nanocube under light irradiation,” The Journal of Physical Chemistry Letters, vol. 10, no. 6, pp. 1212–1216, 2019. View at: Publisher Site | Google Scholar
  25. Y. Luo, S. Suzuki, Z. Wang et al., “Construction of spatial charge separation facets on BaTaO2N crystals by flux growth approach for visible-light-driven H2 production,” ACS Applied Materials & Interfaces, vol. 11, no. 25, pp. 22264–22271, 2019. View at: Publisher Site | Google Scholar
  26. Q. Zhang, Z. Li, S. Wang et al., “Effect of redox cocatalysts location on photocatalytic overall water splitting over cubic NaTaO3 semiconductor crystals exposed with equivalent facets,” ACS Catalysis, vol. 6, no. 4, pp. 2182–2191, 2016. View at: Publisher Site | Google Scholar
  27. P. Chen, H. Liu, W. Cui, S. C. Lee, L. Wang, and F. Dong, “Bi-based photocatalysts for light-driven environmental and energy applications: structural tuning, reaction mechanisms, and challenges,” EcoMat, vol. 2, article e12047, 2020. View at: Publisher Site | Google Scholar
  28. A. Nakada, A. Saeki, M. Higashi, H. Kageyama, and R. Abe, “Two-step synthesis of Sillén-Aurivillius type oxychlorides to enhance their photocatalytic activity for visible-light-induced water splitting,” Journal of Materials Chemistry A, vol. 6, no. 23, pp. 10909–10917, 2018. View at: Publisher Site | Google Scholar
  29. D. Kato, K. Hongo, R. Maezono et al., “Valence band engineering of layered bismuth oxyhalides toward stable visible-light water splitting: Madelung site potential analysis,” Journal of the American Chemical Society, vol. 139, no. 51, pp. 18725–18731, 2017. View at: Publisher Site | Google Scholar
  30. S. Wang, B. Huang, Z. Wang et al., “A new photocatalyst: Bi2TiO4F2 nanoflakes synthesized by a hydrothermal method,” Dalton Transactions, vol. 40, no. 47, pp. 12670–12675, 2011. View at: Publisher Site | Google Scholar
  31. K. Ogawa, A. Nakada, H. Suzuki et al., “Flux synthesis of layered oxyhalide Bi4NbO8Cl photocatalyst for efficient Z-scheme water splitting under visible light,” ACS Applied Materials & Interfaces, vol. 11, pp. 5642–5650, 2019. View at: Publisher Site | Google Scholar
  32. X. Tao, Y. Zhao, L. Mu, S. Wang, R. Li, and C. Li, “Bismuth tantalum oxyhalogen: a promising candidate photocatalyst for solar water splitting,” Advanced Energy Materials, vol. 8, no. 1, article 1701392, 2018. View at: Publisher Site | Google Scholar
  33. L. Li, Q. Han, L. Tang et al., “Flux synthesis of regular Bi4TaO8Cl square nanoplates exhibiting dominant exposure surfaces of {001} crystal facets for photocatalytic reduction of CO2 to methane,” Nanoscale, vol. 10, no. 4, pp. 1905–1911, 2018. View at: Publisher Site | Google Scholar
  34. X. Tao, Y. Wang, J. Qu, Y. Zhao, R. Li, and C. Li, “Achieving selective photocatalytic CO2 reduction to CO on bismuth tantalum oxyhalogen nanoplates,” Journal of Materials Chemistry A, vol. 9, no. 35, pp. 19631–19636, 2021. View at: Publisher Site | Google Scholar
  35. X. Tao, W. Shi, B. Zeng et al., “Photoinduced surface activation of semiconductor photocatalysts under reaction conditions: a commonly overlooked phenomenon in photocatalysis,” ACS Catalysis, vol. 10, no. 10, pp. 5941–5948, 2020. View at: Publisher Site | Google Scholar
  36. X. Tao, Y. Gao, S. Wang et al., “Interfacial charge modulation: an efficient strategy for boosting spatial charge separation on semiconductor photocatalysts,” Advanced Energy Materials, vol. 9, no. 13, article 1803951, 2019. View at: Publisher Site | Google Scholar
  37. S. Chen, T. Takata, and K. Domen, “Particulate photocatalysts for overall water splitting,” Nature Reviews Materials, vol. 2, no. 10, 2017. View at: Publisher Site | Google Scholar
  38. W. Kurashige, Y. Mori, S. Ozaki et al., “Activation of water-splitting photocatalysts by loading with ultrafine Rh–Cr mixed-oxide cocatalyst nanoparticles,” Angewandte Chemie, International Edition, vol. 132, no. 18, pp. 7142–7148, 2020. View at: Publisher Site | Google Scholar
  39. A. Nakada, H. Suzuki, J. J. M. Vequizo et al., “Fe/Ru oxide as a versatile and effective cocatalyst for boosting Z-scheme water-splitting: suppressing undesirable backward electron transfer,” ACS Applied Materials & Interfaces, vol. 11, no. 49, pp. 45606–45611, 2019. View at: Publisher Site | Google Scholar
  40. A. Adenle, H. Zhou, X. Tao et al., “Crystal facet modulation of Bi2WO6 microplates for spatial charge separation and inhibiting reverse reaction,” Chemical Communications, vol. 57, no. 88, pp. 11637–11640, 2021. View at: Publisher Site | Google Scholar
  41. Y. Zhao, C. Ding, J. Zhu et al., “A hydrogen farm strategy for scalable solar hydrogen production with particulate photocatalysts,” Angewandte Chemie, International Edition, vol. 59, no. 24, pp. 9653–9658, 2020. View at: Publisher Site | Google Scholar

Copyright © 2022 Abraham Adenle et al. Exclusive Licensee Beijing Institute of Technology Press. Distributed under a Creative Commons Attribution License (CC BY 4.0).

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