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<p>Metal sulfides like CdS hold promise for solar-driven H<sub>2</sub>O<sub>2</sub> productions but suffer from rapid charge recombination and severe photocorrosion. This study introduces a dual-functional strategy synergizing sulfur vacancy (S<sub>v</sub>) engineering and polydopamine (PDA) coating to overcome these limitations. S<sub>v</sub>-CdS nanorods were hydrothermally synthesized with tunable vacancy concentrations, followed by <i>in-situ</i> PDA deposition to construct a direct Z-scheme heterojunction. X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) calculations reveal that the introduction of S vacancies reduces the work function of CdS, facilitating energy level alignment with PDA and enabling efficient electron transfer from CdS to PDA. By tuning the concentration of S vacancies, the charge transfer efficiency can be maximized. As a result, the photocatalytic H<sub>2</sub>O<sub>2</sub> production rate reaches 2539.5 µmol g<sup>−1</sup> h<sup>−1</sup> under visible light, and further increases to 4395.5 µmol g<sup>−1</sup> h<sup>−1</sup> after PDA encapsulation —15.6 times higher than that of pristine CdS. Concurrently, PDA enhances O<sub>2</sub> adsorption and protects S<sub>v</sub>-CdS from photocorrosion. S<sub>v</sub>-CdS@PDA exhibited superior photostability compared to S<sub>v</sub>-CdS after three consecutive photocatalytic cycles. Mechanistic studies suggest that the Z-scheme heterojunction effectively separates electron-hole pairs: electrons in the conduction band of CdS reduce O<sub>2</sub> to ·O<sub>2</sub><sup>−</sup>, which is subsequently converted to H<sub>2</sub>O<sub>2</sub>, while holes in the valence band of S<sub>v</sub>-CdS oxidize water to replenish O<sub>2</sub>. This work provides fundamental insights into engineering charge transfer and stability in sulfide-based photocatalysts.</p>

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Synergistic sulfur vacancy and polydopamine engineering in Sv-CdS@PDA Z-scheme heterojunctions for photocatalytic H2O2 production with robust anticorrosion

  • 期刊论文

  • 发表日期：

    2025年11月10日

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  • Guangyuan Chen,
  • Tingting Tang,
  • Yubao Li,
  • Chenyang Lin,
  • Shijian Zhou,
  • Yan Kong

摘要

Metal sulfides like CdS hold promise for solar-driven H2O2 productions but suffer from rapid charge recombination and severe photocorrosion. This study introduces a dual-functional strategy synergizing sulfur vacancy (Sv) engineering and polydopamine (PDA) coating to overcome these limitations. Sv-CdS nanorods were hydrothermally synthesized with tunable vacancy concentrations, followed by in-situ PDA deposition to construct a direct Z-scheme heterojunction. X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) calculations reveal that the introduction of S vacancies reduces the work function of CdS, facilitating energy level alignment with PDA and enabling efficient electron transfer from CdS to PDA. By tuning the concentration of S vacancies, the charge transfer efficiency can be maximized. As a result, the photocatalytic H2O2 production rate reaches 2539.5 µmol g−1 h−1 under visible light, and further increases to 4395.5 µmol g−1 h−1 after PDA encapsulation —15.6 times higher than that of pristine CdS. Concurrently, PDA enhances O2 adsorption and protects Sv-CdS from photocorrosion. Sv-CdS@PDA exhibited superior photostability compared to Sv-CdS after three consecutive photocatalytic cycles. Mechanistic studies suggest that the Z-scheme heterojunction effectively separates electron-hole pairs: electrons in the conduction band of CdS reduce O2 to ·O2−, which is subsequently converted to H2O2, while holes in the valence band of Sv-CdS oxidize water to replenish O2. This work provides fundamental insights into engineering charge transfer and stability in sulfide-based photocatalysts.