Directed Charge Transfer-Driven Efficient Photocatalytic Hydrogen Production in Dual S-Scheme WS₂/Co₉S₈/ZnCdS Heterojunction

Abstract

ZnCdS-based photocatalysts exhibit great potential for solar-driven hydrogen (H₂) evolution due to their tunable bandgaps and visible-light absorption. Nevertheless, rapid charge recombination and structural instability hinder their practical implementation. To overcome these challenges, this work proposes a dual S-scheme heterojunction design strategy utilizing polyoxometalates (POMs) as precursors to precisely control the heterojunction interfacial coupling. A dual S-scheme WS₂/Co₉S₈/ZnCdS system was synthesized via a precursor-guided sulfidation process, using K₇[Co₂W₁₁O₄₀H₂]·15H₂O (Co₂W₁₁) POM clusters as dual-source templates. This approach enables the simultaneous achievement of tight interfacial coupling and a simplified single-interface architecture. The charge transfer mechanism within the heterojunction was systematically investigated through analyses of the Fermi level, band structure, ultrafast timescale femtosecond transient absorption (fs-TAS), time-resolved photoluminescence (TRPL), in situ x-ray photoelectron spectroscopy (XPS), and synchrotron radiation. The dual S-scheme heterojunction not only expands the light absorption range of ZnCdS but also promotes efficient charge migration and separation. Under visible-light irradiation (λ ≥ 420 nm), this dual S-scheme heterojunction exhibits remarkable stability and achieves a hydrogen evolution rate of up to 15.66 mmol g⁻¹ h⁻¹, surpassing most reported noble metal-free ZnCdS-based photocatalysts. This research provides a robust methodology for developing dual S-scheme heterojunctions that enhance photocatalytic hydrogen evolution efficiency.

Keywords

dual S-scheme heterojunction / photocatalytic hydrogen / polyoxometalates / ZnCdS

References

[1] D. Zhang, Z. Gao, D. Yang, et al., “Crystal-Interface-Mediated Self-Assembly of ZnIn₂S₄/CdS S-Scheme Heterojunctions Toward Efficient Photocatalytic Hydrogen Production,” Carbon Energy 7, no. 6 (2025): e707.

[2] W. Li, D. Li, Z. Chen, et al., “High-Efficient Degradation of Dyes by Zn_xCd_1−xS Solid Solutions Under Visible Light Irradiation,” Journal of Physical Chemistry C 112, no. 38 (2008): 14943–14947.

[3] X. Wang, B. Liu, S. Ma, et al., “Induced Dipole Moments in Amorphous ZnCdS Catalysts Facilitate Photocatalytic H₂ Evolution,” Nature Communications 15, no. 1 (2024): 2600.

[4] J. Wang, X. Niu, R. Wang, et al., “High-Entropy Alloy-Enhanced ZnCdS Nanostructure Photocatalysts for Hydrogen Production,” Applied Catalysis B: Environment and Energy 362 (2025): 124763.

[5] J. Du, L. Zhang, L. Zhang, X. Ma, and Z. Jin, “Polarised Electric Field Induced Efficient Photocatalytic Hydrogen Production at NiCrO₄/ZnCdS Heterogeneous Interface,” Journal of Colloid and Interface Science 689 (2025): 137211.

[6] B. Zhu, C. Jiang, J. Xu, Z. Zhang, J. Fu, and J. Yu, “Quantum Dots in S-Scheme Photocatalysts,” Materials Today 82 (2025): 251–273.

[7] J. Cai, B. Liu, S. Zhang, et al., “ZnIn₂S₄/MOF S-Scheme Photocatalyst for H₂ Production and Its Femtosecond Transient Absorption Mechanism,” Journal of Materials Science & Technology 197 (2024): 183–193.

[8] K. Meng, J. Zhang, B. Zhu, C. Jiang, H. García, and J. Yu, “Interfacial Charge Transfer in ZnO/COF S-Scheme Photocatalyst via Zn−N Bond,” Advanced Materials 37, no. 29 (2025): 2505088.

[9] M. Liu, W. Yang, R. Xiao, et al., “Construction of Dual S-Scheme Ag₂CO₃/Bi₄O₅I₂/g-C₃N₄ Heterostructure Photocatalyst With Enhanced Visible-Light Photocatalytic Degradation for Tetracycline,” Journal of Colloid and Interface Science 438 (2022): 135471.

[10] J. Wang, Q. Hao, R. Yang, et al., “A Dual S-Scheme Heterojunction SrTiO₃/SrCO₃/C-Doped TiO₂ as H₂ Production Photocatalyst and Its Charge Transfer Mechanism,” Applied Catalysis B: Environment and Energy 356 (2024): 124232.

[11] H. Ren, A. Labidi, T. Chang, Z. Miao, X. Feng, and C. Wang, “Coordination Engineering in Dual S-Scheme Heterojunction for Photocatalytic Applications: Research Progress, Key Challenges and Future Horizons,” Coordination Chemistry Reviews 548 (2026): 217183.

[12] P. Li, Y. Li, Q. Liang, et al., “Uncovering the Critical Role of Ni on Surface Lattice Stability in Anionic Redox Active Li_1.2Ni_0.2Mn_0.6O₂,” Carbon Energy 7, no. 6 (2025): e699.

[13] W. Sun, B. Zhao, C. J. Gómez-García, et al., “Constructing Molecular Junctions With High-Spin Metal Sites in POMOFs to Trigger Heteropoly Blue States for Photocatalytic H₂ Production,” ACS Catalysis 15, no. 9 (2025): 7601–7612.

[14] D. Nowicka, N. Vadra, E. Wieczorek-Szweda, V. Patroniak, and A. Gorczyński, “Overview of Wells–Dawson Polyoxometalates: From Structure and Functionalization to Application,” Coordination Chemistry Reviews 519 (2024): 216091.

[15] S. Fu, S. Ullah Khan, R. Yang, et al., “High-Performance Heterometallic Photocatalysts Afforded by Polyoxometalate Synthons for Efficient H₂ Production,” Journal of Colloid and Interface Science 666 (2024): 496–504.

[16] M. A. Barakat, R. Kumar, T. Almeelbi, B. A. Al-Mur, and J. O. Eniola, “Sustainable Visible Light Photocatalytic Scavenging of the Noxious Organic Pollutant Using Recyclable and Reusable Polyaniline Coupled WO₃/WS₂ Nanohybrid,” Journal of Cleaner Production 330 (2022): 129942.

[17] K. M. Naik, A. K. Chourasia, and C. S. Sharma, “N, S Co-Doped Carbon Anchored Co₉S₈ Cathode: Advancing Sustainable Energy Through Efficient Li-CO₂ Mars Batteries,” Journal of Power Sources 608 (2024): 234623.

[18] J. Liu, X. Meng, J. Xie, et al., “Dual Active Sites Engineering on Sea Urchin-Like CoNiS Hollow Nanosphere for Stabilizing Oxygen Electrocatalysis via a Template-Free Vulcanization Strategy,” Advanced Functional Materials 33, no. 22 (2023): 2300579.

[19] X. Zhao, J. Chen, Z. Bi, et al., “Electron Modulation and Morphology Engineering Jointly Accelerate Oxygen Reaction to Enhance Zn-Air Battery Performance,” Advanced Science 10, no. 8 (2023): 2205889.

[20] S. Liu, H. Wang, S. Wang, et al., “Engineering Morphology and Ni Substitution of Ni_xCo_3−xO₄ Spinel Oxides to Promote Catalytic Combustion of Ethane: Elucidating the Influence of Oxygen Defects,” ACS Catalysis 13, no. 7 (2023): 4683–4699.

[21] W. Chen, D. Zhang, J. Zou, and J. Luo, “A Full-Scale Analysis of Absorption Edges in Dye-Doped Nonlinear Optical Polymers,” Small Methods 8, no. 11 (2024): 2400162.

[22] C. He, X. Hu, J. Wang, et al., “Defect Engineered 2D Mesoporous Mo−Co−O Nanosheets With Crystalline–Amorphous Composite Structure for Efficient Oxygen Evolution,” Science China Materials 65, no. 12 (2022): 3470–3478.

[23] N. Saini, K. Dhingra, A. Kumar, and K. Kailasam, “Molecular Structural Engineering of Donor–Acceptor-Based Porous Organic Polymers for Sulfide Photooxidation in Water: A Sustainable Approach,” Green Chemistry 26, no. 19 (2024): 10314–10323.

[24] L. Zhang, J. Zhang, J. Yu, and H. García, “Charge-Transfer Dynamics in S-Scheme Photocatalyst,” Nature Reviews Chemistry 9 (2025): 328–342.

[25] H. Ran, X. Liu, L. Ye, et al., “Construction of CYANO-COF/ZnIn₂S₄ S-Scheme Heterojunction for Boosted Photocatalytic Hydrogen Generation,” Journal of Materials Science & Technology 234 (2025): 24–30.

[26] T. Yang, Z.-W. Chen, X.-Z. Yue, Q.-C. Liu, S.-S. Yi, and Y.-F. Zhu, “Interfacial Charge Transfer Bridge Prolongs Carrier Recombination Lifetimes of CoFe Metal-Thiolate Framework/Hematite Photoanode for Water Oxidation,” Advanced Functional Materials 34, no. 18 (2024): 2313767.

[27] S. Khan, R. Shrestha, M. Jin, et al., “Designing Robust Quasi-2D Perovskites Thin Films for Stable Light-Emitting Applications,” Advanced Materials 37, no. 25 (2025): 2413412.

[28] M. Liu, W. Yang, R. Xiao, et al., “Anisotropic Dual S-Scheme Heterojunctions Mimic Natural Photosynthetic System for Boosting Photoelectric Response,” Angewandte Chemie 136, no. 33 (2024): e202407481.

[29] J. Wang, Y. Wang, J. Cheng, et al., “Abundant Vacancies Induced High Polarization-Attenuation Effects in Flower-Like WS₂ Microwave Absorbers,” Journal of Materials Science & Technology 194 (2024): 193–202.

[30] Z. Xu, W. Zuo, Y. Yu, J. Liu, G. Cheng, and P. Zhao, “Surface Reconstruction Facilitated by Fluorine Migration and Bimetallic Center in NiCo Bimetallic Fluoride Toward Oxygen Evolution Reaction,” Advanced Science 11, no. 6 (2024): 2306758.

[31] T. Hu, Y. Zhao, Y. Yang, et al., “Development of Inverse-Opal-Structured Charge-Deficient Co₉S₈@Nitrogen-Doped-Carbon to Catalytically Enable High Energy and High Power for the Two-Electron Transfer I⁺/I⁻ Electrode,” Advanced Materials 36, no. 18 (2024): 2312246.

[32] H. Zhao, X. Zhao, L. Shen, H. Liu, and X. Li, “Synergistic Effects of Cocatalyst and Homojunction/Heterojunction With Boosted Photocatalytic H₂ Evolution Over Zn_0.5Cd_0.5S/NDs,” Chemical Engineering Journal 470 (2023): 143925.

[33] Q. Chen, Q. Zhang, B. Chen, et al., “Enhanced Long-Term Performance of Sulfides in Oxygen Evolution Reaction by Sulfate Ion-Assisted Strategy,” Advanced Functional Materials 34, no. 44 (2024): 2406233.

[34] M. Cai, C. He, H. Yu, and A. Shui, “Fabrication of the Ternary Dual S-Scheme ZnO/ZnS/In₂S₃ Heterojunction for Enhancing Pollutant Photodegradation,” Applied Surface Science 652 (2024): 159284.

[35] H. Man, J. Feng, S. Wang, et al., “Ultra-Fast Surface Reconstruction Enabled by the Built-In Electric Field in Heterostructured CoS₂/CuS for Water Electrolysis,” Cell Reports Physical Science 3, no. 10 (2022): 101059.

[36] Z. Chen, W. Gong, J. Wang, et al., “Metallic W/WO₂ Solid-Acid Catalyst Boosts Hydrogen Evolution Reaction in Alkaline Electrolyte,” Nature Communications 14, no. 1 (2023): 5363.

[37] Q. Liu, X. Li, Z. Xiao, et al., “Stable Metallic 1T-WS₂ Nanoribbons Intercalated With Ammonia Ions: The Correlation Between Structure and Electrical/Optical Properties,” Advanced Materials 27, no. 33 (2015): 4837–4844.

[38] Y. Liu, Z. Zhang, J. Tan, et al., “Deciphering the Contributing Motifs of Reconstructed Cobalt(II) Sulfides Catalysts in Li-CO₂ Batteries,” Nature Communications 15, no. 1 (2024): 2167.

[39] Y. Li, A. Feng, L. Dai, et al., “Progress on the Design of Electrocatalysts for Large-Current Hydrogen Production by Tuning Thermodynamic and Kinetic Factors,” Advanced Functional Materials 34, no. 28 (2024): 2316296.

[40] J. Shi, Y. Bao, R. Ye, et al., “Recent Progress and Perspective of Electrocatalysts for the Hydrogen Evolution Reaction,” Catalysis Science & Technology 15 (2025): 2104–2131.

[41] S.-X. Wu, Y. Yang, C. Qin, Y. H. Hou, X. L. Wang, and Z. M. Su, “Organophosphate Functionalized of {Mo₂₄₀} Polyoxomolybdate Dodecahedra,” Tungsten 5, no. 2 (2023): 247–253.

[42] F.-R. Li, T. Ji, and W.-L. Chen, “A Tri-Vanadium-Capped Keggin Phosphomolybdate: Synthesis, Characterization, Photocatalytic and Bifunctional Electrocatalytic Properties,” Tungsten 4, no. 2 (2022): 99–108.

[43] X. Yue, S. Wang, J. Gao, S. Wang, and W. Ding, “Effects of Mesopore Size on Ethyl Acetate Adsorption–Desorption Behaviors Over Hierarchical ZSM-5/MCM-41 Molecular Sieves,” Separation and Purification Technology 336 (2024): 126228.

[44] R. Pan, X. Ge, Q. Liu, et al., “Synergic Delocalized-Conjugate and Electron-Deficient Effect and Mesoporous Channel Promote Photocatalytic Coupling H₂ Evolution With Benzyl-Alcohol Oxidation,” Advanced Functional Materials 34, no. 17 (2024): 2315212.

[45] J. Li, Y. Ma, C. Zhang, et al., “Green Electrosynthesis of 3,3′-Diamino-4,4′-Azofurazan Energetic Materials Coupled With Energy-Efficient Hydrogen Production Over Pt-Based Catalysts,” Nature Communications 14, no. 1 (2023): 8146.

[46] X. Han, X. Wu, Y. Deng, et al., “Ultrafine Pt Nanoparticle-Decorated Pyrite-Type CoS₂ Nanosheet Arrays Coated on Carbon Cloth as a Bifunctional Electrode for Overall Water Splitting,” Advanced Energy Materials 8, no. 24 (2018): 1800935.

[47] Y. Zhang, Q. Wang, L. Wu, et al., “Manipulating Photogenerated Electron Flow in Nickel Single-Atom Catalysts for Photocatalytic CO₂ Reduction Into Tunable Syngas,” Carbon Energy 6, no. 8 (2024): e533.

[48] J. Zhou, B. Gao, D. Wu, et al., “Enhanced Photocatalytic Activity of Lead-Free Cs₂TeBr₆/g-C₃N₄ Heterojunction Photocatalyst and Its Mechanism,” Advanced Functional Materials 34, no. 3 (2024): 2308411.

[49] Q. Lu, N. Yang, L. Zuo, W. Fang, J. Dong, and X. Zeng, “Photostability and Visible-Light-Driven Photoactivity Enhancement of Hierarchical C@ZnCdS/ZnS/MoS₂,” Nano Express 5, no. 1 (2024): 015025.

[50] H. Chen, Y. Zhu, J. Wu, et al., “Cu-Doped ZnCdS-Based Photocatalyst for Efficient Photocatalytic Hydrogen Production by Photothermal Assistance,” Case Studies in Thermal Engineering 61 (2024): 104970.

[51] S. Liu, W. Wang, S. Shi, et al., “Hydrogen-Bonded Organic Framework Derived Ultra-Fine ZnCdS/ZnS Heterojunction With High-Porosity for Efficient Photocatalytic Hydrogen Production,” Applied Surface Science 657 (2024): 159795.

[52] W. Fan, H. Chang, J. Zhong, et al., “Facile Synthesis of ZnCdS Quantum Dots via a Novel Photoetching MOF Strategy for Boosting Photocatalytic Hydrogen Evolution,” Separation and Purification Technology 330 (2024): 125258.

[53] D. Yang, Z.-G. Li, X. Zhang, et al., “Rational Design of ZnCdS/TpPa-1-COF Heterostructure Photocatalyst by Strengthening the Interface Connection in Solar Hydrogen Production Reactions,” Nano Research 17, no. 3 (2024): 1027–1034.

[54] X. Du, J. Hu, Q. Sun, et al., “Rapid Microwave Preparation of CuS/ZnCdS Z-Scheme Heterojunction for Efficient Photocatalytic Hydrogen Evolution,” International Journal of Hydrogen Energy 51 (2024): 936–945.

[55] C. Huang, N. Liu, Y. Zhou, H. Mao, F. Qi, and X. Ouyang, “Construction of 3D/0D S_v-ReS₂/ZnCdS Hierarchical Structure With Improved Interfacial Charge Transfer for Enhanced Photocatalytic Hydrogen Evolution,” Separation and Purification Technology 354 (2025): 128838.

[56] P. Bai, L. Junyu Lang, S. Wang, H. Tong, W. Du, and Z. Chai, “Enhanced Interfacial Charge Transfer by Oxygen Vacancies in ZnCdS/NiCo-LDH Heterojunction for Efficient H₂ Evolution,” Applied Surface Science 643 (2024): 158715.

[57] J. Zhao, K. Li, H. She, et al., “Highly Efficient Photocatalytic Hydrogen Production by ZnCdS Composite Catalyst Modified With NiCoP Nanosheets Prepared by LDH Precursor,” Journal of Colloid and Interface Science 649 (2023): 416–425.

[58] K. Liu, S. Yang, W. Li, et al., “Non-Noble-Metal NiS Promoted Charge Separation and Photocatalytic Hydrogen Evolution for ZnCdS Nano-Islands on Spherical SiO₂,” Fuel 337 (2023): 126840.

[59] M. Du, S. Ji, C. Qian, et al., “Anchoring 0D Cd_0.5Zn_0.5S Nanoparticles on a 3D Porous N-Doped Ti₃C₂T_x MXene Matrix for Efficient Photocatalytic Hydrogen Evolution,” Journal of Materials Chemistry C 11, no. 32 (2023): 10973–10984.

[60] Z. Li, A. Meng, X. Sang, W. Li, J. Zhang, and Z. Wang, “Efficient and Stable Hydrogen Evolution From ZnWO₄/Zn_1.95Cd_8.05S₁₀-DETA via S-Scheme Heterojunction Under Visible Light Irradiation Without Co-Catalysts,” International Journal of Hydrogen Energy 51 (2024): 777–786.

[61] M. Ahmad, X. Quan, S. Chen, H. Yu, and Z. Zeng, “Operating Redox Couple Transport Mechanism for Enhancing Photocatalytic H₂ Generation of Pt and CrO_x-Decorated ZnCdS Nanocrystals,” Applied Catalysis, B: Environmental 283 (2021): 119601.

[62] L. Zuo, N. Yang, W. Xia, X. Zeng, and R. Cao, “Z-Scheme NiS@ZnCdS Heterostructures and Their Boosted Photocatalytic H₂ Evolution,” Applied Surface Science 689 (2025): 162447.

[63] X. Hao, D. Xiang, Z. Jin, et al., “Zn-Vacancy Engineered S-Scheme ZnCdS/ZnS Photocatalyst for Highly Efficient Photocatalytic H₂ Evolution,” ChemCatChem 13, no. 22 (2021): 4738–4750.

[64] H. Yang, C. Li, M. Mao, et al., “Synthesis of Type-S Ni₃S₄/ZnCdS Quantum Dots via Constitution Controller l-Cysteine for Photocatalytic H₂ Evolution,” ACS Applied Nano Materials 7, no. 18 (2024): 22093–22103.

[65] J. Chen, Z. Shen, S. Lv, et al., “Fabricating Sandwich-Shelled ZnCdS/ZnO/ZnCdS Dodecahedral Cages With ‘One Stone’ as Z-Scheme Photocatalysts for Highly Efficient Hydrogen Production,” Journal of Materials Chemistry A 6, no. 40 (2018): 19631–19642.

[66] T. J. Siang, P. Zhang, B. Chen, and W.-J. Ong, “Surface Defect Engineering of ZnCoS in ZnCdS With Twin Crystal Structure for Visible-Light-Driven H₂ Production Coupled With Benzyl Alcohol Oxidation,” Chinese Journal of Catalysis 69 (2025): 84–98.

[67] L. Song, S. Zhang, D. Liu, S. Sun, and J. Wei, “High-Performance Hydrogen Evolution of NiB/ZnCdS Under Visible Light Irradiation,” International Journal of Hydrogen Energy 45, no. 15 (2020): 8234–8242.

[68] H. Gong, X. Zhang, G. Wang, Y. Liu, Y. Li, and Z. Jin, “Dodecahedron ZIF-67 Anchoring ZnCdS Particles for Photocatalytic Hydrogen Evolution,” Molecular Catalysis 485 (2020): 110832.

[69] S. Wang, Y. Ke, F. Jin, Y. Li, and Z. Jin, “The Built-In Electric Field Regulates the D-Band Center of the FeCo₂O₄/ZnCdS Heterojunction to Enhance Photocatalytic Hydrogen Evolution,” Chemsuschem 18, no. 16 (2025): e202500950.

[70] X. Che, T. W. B. Lo, X. Bai, et al., “PtCo Clusters Anchored on Defect-Rich Heterometal Nanosheets for Electrochemical H₂ Production,” Journal of Colloid and Interface Science 700, no. 3 (2025): 138555.

[71] H. Su, W. Wang, R. Shi, et al., “Recent Advances in Quantum Dot Catalysts for Hydrogen Evolution: Synthesis, Characterization, and Photocatalytic Application,” Carbon Energy 5, no. 9 (2023): e280.

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