Submitted Successfully!
To reward your contribution, here is a gift for you: A free trial for our video production service.
Thank you for your contribution! You can also upload a video entry or images related to this topic.
Version Summary Created by Modification Content Size Created at Operation
1 -- 1185 2023-06-21 04:41:09 |
2 format correct Meta information modification 1185 2023-06-25 05:28:28 |

Video Upload Options

Do you have a full video?


Are you sure to Delete?
If you have any further questions, please contact Encyclopedia Editorial Office.
Yan, Y.; Chen, Z.; Cheng, X.; Shi, W. Mechanisms of Photocatalytic Overall Water Splitting. Encyclopedia. Available online: (accessed on 24 June 2024).
Yan Y, Chen Z, Cheng X, Shi W. Mechanisms of Photocatalytic Overall Water Splitting. Encyclopedia. Available at: Accessed June 24, 2024.
Yan, Yujie, Zhouze Chen, Xiaofang Cheng, Weilong Shi. "Mechanisms of Photocatalytic Overall Water Splitting" Encyclopedia, (accessed June 24, 2024).
Yan, Y., Chen, Z., Cheng, X., & Shi, W. (2023, June 21). Mechanisms of Photocatalytic Overall Water Splitting. In Encyclopedia.
Yan, Yujie, et al. "Mechanisms of Photocatalytic Overall Water Splitting." Encyclopedia. Web. 21 June, 2023.
Mechanisms of Photocatalytic Overall Water Splitting

Photocatalytic overall water splitting in solar–chemical energy conversion can effectively mitigate environmental pollution and resource depletion. Stable ternary metal indium zinc sulfide (ZnIn2S4) is considered one of the ideal materials for photocatalytic overall water splitting due to its unique electronic and optical properties, as well as suitable conduction and valence band positions for suitable photocatalytic overall water splitting, and it has attracted widespread researcher interest. 

photocatalytic overall water splitting ZnIn2S4 doping vacancy

1. Introduction

The world is currently suffering from environmental pollution and resource depletion, with energy issues looming large. According to relevant studies, the annual global consumption of energy is equivalent to the solar energy reaching the Earth’s surface every hour; therefore, solar energy as an abundant, non-polluting natural resource has replaced the traditional fuel fossil as a research hotspot [1]. However, solar energy has limitations such as intermittency and low density, so an effective storage method is needed to make efficient use of solar energy [2]. Since 1972, when it was reported that TiO2 semiconductors could produce hydrogen and oxygen when irradiated by ultraviolet light, photocatalysis, which uses solar energy to convert it into storable chemical energy, has attracted extensive research [3].
Hydrogen, as a clean, high-energy-density solar fuel, is the ideal energy carrier. Since most photocatalytic hydrogen production studies require the use of sacrificial agents to achieve this, photocatalytic overall water splitting is considered a low-cost, ideal method for converting solar energy into hydrogen energy [4][5][6]. The photocatalytic overall water splitting process is based on three fundamental photocatalytic processes: photocatalyst absorption of photons to generate electron–hole pairs, photogenerated charge transfer and separation, and surface redox reactions. A variety of semiconductor catalysts such as metal oxides, metal sulfides, and nitrides are currently used in the field of photocatalytic overall water splitting [7][8][9][10][11][12]. Among them, metal sulfides have the advantages of good charge transfer ability, suitable energy band structure for overall water splitting, and excellent light collection ability to become one of the potential catalysts in photocatalytic overall water splitting [13].
Metal sulfides are mainly classified into binary metal sulfides such as CdS, MoS2, and ZnS; ternary metal sulfides such as ZnIn2S4 and CuInS4; and polymetallic sulfides such as AgZnInS [14]. Most of these binary sulfides have some disadvantages that are more difficult to improve, such as ZnS-based photocatalysts having a poor photo-response, responding only to ultraviolet (UV) light, and CdS-based catalysts having severe photo-corrosion and poor stability, whereas ternary metal sulfides tend to be more stable [15][16][17][18]. Zinc indium sulfide (ZnIn2S4), a ternary metal sulfide belonging to the AB2X4 family, has unique electronic and optical properties. Compared with conventional photocatalysts, ZnIn2S4 has a narrower band gap, adjustable between about 2.06 and 2.85 eV, and has thermodynamically suitable conduction and valence band positions for photocatalytic overall water splitting as well as a strong visible-light response range [19][20]. In addition, ZnIn2S4 has many advantages such as strong photostability, relatively environmentally friendly chemical composition, ease of preparation, and wide distribution of raw materials [21]. Therefore, ZnIn2S4 is a more desirable material for photocatalytic overall water splitting.
Although ZnIn2S4 has many advantages, in practical applications, ZnIn2S4-based photocatalysts suffer from difficulties in achieving one-component photocatalytic overall water splitting or low photocatalytic overall water splitting efficiency, mainly due to the slow photo-generated charge separation and migration efficiency and weak solar energy utilization [22][23][24]. Therefore, appropriate modification strategies such as elemental doping, vacancy engineering, the construction of heterojunctions, and the loading of co-catalysts are required to improve the performance of ZnIn2S4-based photocatalyst materials.
Researchers have actively explored how to improve the performance of ZnIn2S4-based photocatalysts and have reported on a review of ZnIn2S4 photocatalysts from different perspectives. For example, Liu et al. reviewed the research progress of ZnIn2S4-based photocatalysts constructed with heterojunctions for photocatalytic hydrogen production [25]. Yadav et al. reviewed various modification strategies to improve the performance of ZnIn2S4-based photocatalysts and summarized their applications in water pollution treatment, CO2 reduction, etc. [26]. However, previous reports are mainly based on applications such as hydrogen production and pollutant treatment, and there is no systematic summary of the research progress on ZnIn2S4-based photocatalysts for achieving photocatalytic overall water splitting.

2. Mechanisms of Photocatalytic Overall Water Splitting

Photocatalytic overall water splitting consists of two half-reactions, the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). Theoretically, in order to achieve overall water splitting, the semiconductor band gap should be no less than 1.23 eV under standard conditions, the potential at the bottom of the conduction band should be less than 0 eV (H2/H+ = 0 eV vs. NHE, pH = 0), and that at the top of the valence band should be greater than 1.23 eV (H2O/O2 = 1.23 eV vs. NHE, pH = 0) [27]. The redox potential of water is all located within the band gap of the photocatalyst and photocatalytic overall water splitting is thermodynamically feasible. However, photocatalytic overall water splitting is an uphill reaction requiring additional energy to promote water splitting, which is a thermodynamically unfavorable process (G > 0); therefore, hydrogen and oxygen are prone to the reverse reaction and H2O reformation, which severely inhibits the photocatalytic water splitting activity [28].
Semiconductor-based photocatalysts for photocatalytic overall water splitting are based on three basic processes of photocatalysis: under solar irradiation with an energy greater than the band gap of the photocatalyst, photogenerated electrons are excited to leap to the conduction band and photogenerated holes remain in the valence band; photogenerated charges migrate separately to the semiconductor reaction site; and un-recombined photogenerated electrons and holes undergo redox reactions of water at the catalyst surface [29]. From the kinetic point of view, the recombination of photogenerated carriers is much faster than their redox reactions at the surface. The Coulomb force constraints between photogenerated charges and high interfacial potential barriers during charge transfer lead to rapid photogenerated carrier recombination and low utilization efficiency, which severely limit photocatalytic activity [30].
In addition, the range of solar energy utilization affects the photocatalytic activity. According to relevant research reports, the UV content of natural sunlight is less than 3%, the visible content is less than 40%, and the near-infrared occupies about 50% of the sunlight, while photocatalytic materials capture light basically in the UV and visible region, with a low efficiency of solar energy utilization [31][32]. The overall photocatalytic water splitting activity is limited by the low light collection capacity of the catalyst, the rate of photogenerated charge separation and migration, and the surface oxidation reaction [33]. Therefore, researchers have adopted corresponding modification strategies to prepare photocatalysts with high activity and high solar energy utilization efficiency. The stable ternary metal sulfide ZnIn2S4 is one of the ideal materials for photocatalytic overall water splitting due to its advantages. As shown in Scheme 1, the ZnIn2S4-based photocatalysts have thermodynamically suitable conduction and valence band positions for photocatalytic water splitting. However, single-component photocatalytic water splitting is difficult to achieve due to the overall low charge utilization and solar utilization as well as photo-corrosion phenomena. Therefore, modification strategies such as the doping of heteroatoms, formation of defects, construction of heterojunctions, and loading of co-catalysis were adopted to enhance the ZnIn2S4-based photocatalytic performance.
Scheme 1. Schematic diagram of ZnIn2S4-based photocatalyst photocatalytic overall water splitting.


  1. Tao, X.; Zhao, Y.; Wang, S.; Li, C.; Li, R. Recent advances and perspectives for solar-driven water splitting using particulate photocatalysts. Chem. Soc. Rev. 2022, 51, 3561–3608.
  2. Wang, Q.; Domen, K. Particulate Photocatalysts for Light-Driven Water Splitting: Mechanisms, Challenges, and Design Strategies. Chem. Rev. 2020, 120, 919–985.
  3. Fujishima, A.; Honda, K. Electrochemical Photolysis of Water at a Semiconductor Electrode. Nature 1972, 238, 37–38.
  4. Hu, J.; Chen, C.; Zheng, Y.; Zhang, G.; Li, C.M. Spatially Separating Redox Centers on Zlog cheme ZnIn2S4/BiVO4 Hierarchical Heterostructure for Highly Efficient Photocatalytic Hydrogen Evolution. Small 2020, 16, 2002988.
  5. Su, T.; Men, C.; Chen, L.; Chu, B.; Luo, X.; Ji, H.; Chen, J.; Qin, Z. Sulfur Vacancy and Ti3C2Tx Cocatalyst Synergistically Boosting Interfacial Charge Transfer in 2D/2D Ti3C2Tx/ZnIn2S4 Heterostructure for Enhanced Photocatalytic Hydrogen Evolution. Adv. Sci. 2022, 9, 2103715.
  6. Du, C.; Zhang, Q.; Lin, Z.; Yan, B.; Xia, C.; Yang, G. Half-unit-cell ZnIn2S4 monolayer with sulfur vacancies for photocatalytic hydrogen evolution. Appl. Catal. B Environ. 2019, 248, 193–201.
  7. Liu, K.; Zhang, B.; Zhang, J.; Lin, W.; Wang, J.; Xu, Y.; Xiang, Y.; Hisatomi, T.; Domen, K.; Ma, G. Synthesis of Narrow-Band-Gap GaN:ZnO Solid Solution for Photocatalytic Overall Water Splitting. ACS Catal. 2022, 12, 14637–14646.
  8. Zhang, G.G.; Wang, X.C. Oxysulfide Semiconductors for Photocatalytic Overall Water Splitting with Visible Light. Angew. Chem.-Int. Ed. 2019, 58, 15580–15582.
  9. Gogoi, D.; Shah, A.; Rambabu, P.; Qureshi, M.; Golder, A.; Peela, N. Step-Scheme Heterojunction between CdS Nanowires and Facet-Selective Assembly of MnOx-BiVO4 for an Efficient Visible-Light-Driven Overall Water Splitting. ACS Appl. Mater. Interfaces 2021, 13, 45475–45487.
  10. Iwashina, K.; Iwase, A.; Ng, Y.H.; Amal, R.; Kudo, A. Z-schematic water splitting into H2 and O2 using metal sulfide as a hydrogen-evolving photocatalyst and reduced graphene oxide as a solid-state electron mediator. J. Am. Chem. Soc. 2015, 137, 604–607.
  11. Hayat, A.; Sohail, M.; Anwar, U.; Taha, T.A.; El-Nasser, K.S.; Alenad, A.M.; Al-Sehemi, A.G.; Alghamdi, N.A.; Al-Hartomy, O.A.; Amin, M.A.; et al. Enhanced photocatalytic overall water splitting from an assembly of donor-π-acceptor conjugated polymeric carbon nitride. J. Colloid Interface Sci. 2022, 624, 411–422.
  12. Sun, S.; Gao, R.; Liu, X.; Pan, L.; Shi, C.; Jiang, Z.; Zhang, X.; Zou, J.J. Engineering interfacial band bending over bismuth vanadate/carbon nitride by work function regulation for efficient solar-driven water splitting. Sci. Bull. 2021, 67, 389–397.
  13. Pan, Y.; Yuan, X.; Jiang, L.; Yu, H.; Zhang, J.; Wang, H.; Guan, R.; Zeng, G. Recent advances in synthesis, modification and photocatalytic applications of micro/nano-structured zinc indium sulfide. Chem. Eng. J. 2018, 354, 407–431.
  14. Zhu, Q.; Xu, Q.; Du, M.; Zeng, X.; Zhong, G.; Qiu, B.; Zhang, J. Recent Progress of Metal Sulfide Photocatalysts for Solar Energy Conversion. Adv. Mater. 2022, 34, e2202929.
  15. Hao, X.Q.; Zhou, J.; Cui, Z.W.; Wang, Y.C.; Wang, Y.; Zou, Z. Zn-vacancy mediated electron-hole separation in ZnS/g-C3N4 heterojunction for efficient visible-light photocatalytic hydrogen production. Appl. Catal. B Environ. 2018, 229, 41–51.
  16. Xue, S.; Huang, W.; Lin, W.; Xing, W.; Shen, M.; Ye, X.; Liang, X.; Yang, C.; Hou, Y.; Yu, Z. Interfacial engineering of lattice coherency at ZnO-ZnS photocatalytic heterojunctions—ScienceDirect. Chem Catal. 2022, 2, 125–139.
  17. Yu, J.; Yu, Y.; Peng, Z.; Wei, X.; Bei, C. Morphology-dependent photocatalytic H2-production activity of CdS. Appl. Catal. B Environ. 2014, 156–157, 184–191.
  18. Yuan, Y.-J.; Chen, D.; Yu, Z.-T.; Zou, Z.-G. Cadmium sulfide-based nanomaterials for photocatalytic hydrogen production. J. Mater. Chem. A Mater. Energy Sustain. 2018, 6, 11606–11630.
  19. Ren, Y.; Foo, J.J.; Zeng, D.; Ong, W.J. ZnIn2S4-Based Nanostructures in Artificial Photosynthesis: Insights into Photocatalytic Reduction toward Sustainable Energy Production. Small Struct. 2022, 3, 2200017.
  20. Chen, K.; Shi, Y.; Shu, P.; Luo, Z.; Shi, W.; Guo, F. Construction of core–shell FeS2@ZnIn2S4 hollow hierarchical structure S-scheme heterojunction for boosted photothermal-assisted photocatalytic H2 production. Chem. Eng. J. 2023, 454, 140053.
  21. Zhang, G.; Wu, H.; Chen, D.; Li, N.; Xu, Q.; Li, H.; He, J.; Lu, J. A mini-review on ZnIn2S4-Based photocatalysts for energy and environmental application. Green Energy Environ. 2022, 7, 176–204.
  22. Chandrasekaran, S.; Yao, L.; Deng, L.; Bowen, C.; Zhang, Y.; Chen, S.; Lin, Z.; Peng, F.; Zhang, P. Recent advances in metal sulfides: From controlled fabrication to electrocatalytic, photocatalytic and photoelectrochemical water splitting and beyond. Chem. Soc. Rev. 2019, 48, 4178–4280.
  23. Cai, Y.; Shi, Y.; Shi, W.; Bai, S.; Yang, S.; Guo, F. A one-photon excitation pathway in 0D/3D CoS2/ZnIn2S4 composite with nanoparticles on micro-flowers structure for boosted visible-light-driven photocatalytic hydrogen evolution. Compos. Part B Eng. 2022, 238, 109955.
  24. Shi, W.; Hao, C.; Fu, Y.; Guo, F.; Tang, Y.; Yan, X. Enhancement of synergistic effect photocatalytic/persulfate activation for degradation of antibiotics by the combination of photo-induced electrons and carbon dots. Chem. Eng. J. 2022, 433, 133741.
  25. Liu, C.; Zhang, Q.; Zou, Z. Recent advances in designing ZnIn2S4-based heterostructured photocatalysts for hydrogen evolution. J. Mater. Sci. Technol. 2023, 139, 167–188.
  26. Yadav, G.; Ahmaruzzaman, M. Recent progress on synthesis and modifications of ZnIn2S4 based novel hybrid materials for potential applications. Mater. Sci. Eng. B 2023, 292, 116418.
  27. Wang, Z.; Li, C.; Domen, K. Recent developments in heterogeneous photocatalysts for solar-driven overall water splitting. Chem. Soc. Rev. 2019, 48, 2109–2125.
  28. He, R.; Ran, J. Dilemma faced by photocatalytic overall water splitting. J. Mater. Sci. Technol. 2023, 157, 107–109.
  29. Navalon, S.; Dhakshinamoorthy, A.; Alvaro, M.; Ferrer, B.; Garcia, H. Metal-Organic Frameworks as Photocatalysts for Solar-Driven Overall Water Splitting. Chem. Rev. 2023, 123, 445–490.
  30. Bie, C.; Wang, L.; Yu, J. Challenges for photocatalytic overall water splitting. Chem 2022, 8, 1567–1574.
  31. Huang, Y.; Li, D.; Feng, S.; Jia, Y.; Guo, S.; Wu, X.; Chen, M.; Shi, W. Pt Atoms/Clusters on Ni-phytate-sensitized Carbon Nitride for Enhanced NIR-light-driven Overall Water Splitting beyond 800 nm. Angew. Chem. Int. Ed. Engl. 2022, 61, e202212234.
  32. Zhou, P.; Navid, I.A.; Ma, Y.; Xiao, Y.; Wang, P.; Ye, Z.; Zhou, B.; Sun, K.; Mi, Z. Solar-to-hydrogen efficiency of more than 9% in photocatalytic water splitting. Nature 2023, 613, 66–70.
  33. Hu, L.; Huang, J.; Wang, J.; Jiang, S.; Sun, C.; Song, S. Efficiently photocatalytic H2O overall splitting within the strengthened polarized field by reassembling surface single atoms. Appl. Catal. B Environ. 2023, 320, 121945.
Contributors MDPI registered users' name will be linked to their SciProfiles pages. To register with us, please refer to : , , ,
View Times: 371
Revisions: 2 times (View History)
Update Date: 25 Jun 2023
Video Production Service