Surface passivation of the CdS/Cu₂ZnSnS₄ photocathode by a HfO₂ layer was found to be very effective for enhancing the photoelectrochemical stability. The dependence of the photoelectrochemical performance, especially the stability of the Cu₂ZnSnS₄-based photocathode, on the thickness of the HfO₂ film was systematically investigated. The thickness of the HfO₂ layer obviously influenced the PEC stability and efficiency of the Cu₂ZnSnS₄-based photocathode. The CdS/Cu₂ZnSnS₄ photocathode modified with a 6 nm thick HfO₂ layer showed long-term PEC photocurrent stability of over 10 h while still retaining high half-cell solar-to-hydrogen efficiency (HC-STH) of 2.7%. Finally, we fabricated an unbiased solar water splitting device based on the Pt/HfO₂/CdS/Cu₂ZnSnS₄ photocathode in tandem with a BiVO₄ photoanode, and this tandem device not only exhibited an unassisted STH conversion efficiency of 1.046% but also showed a high long-term stability of over 10 h.

中文翻译：

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基于HfO ₂耐光腐蚀膜保护的喷涂Cu ₂ ZnSnS ₄光电阴极的效率超过1％的无偏稳定太阳能分解

发现通过HfO ₂层对CdS / Cu ₂ ZnSnS ₄光电阴极进行表面钝化对于增强光电化学稳定性非常有效。系统地研究了光电化学性能，特别是基于Cu ₂ ZnSnS ₄的光电阴极的稳定性对HfO ₂膜厚度的依赖性。HfO ₂层的厚度明显影响了基于Cu ₂ ZnSnS ₄的光电阴极的PEC稳定性和效率。用6 nm厚的HfO ₂改性的CdS / Cu ₂ ZnSnS ₄光电阴极该层显示出超过10 h的长期PEC光电流稳定性，同时仍保持2.7％的高半电池太阳能-氢效率（HC-STH）。最后，我们结合BiVO ₄光电阳极，制造了基于Pt / HfO ₂ / CdS / Cu ₂ ZnSnS ₄光电阴极的无偏分水装置，该串联装置不仅显示出无辅助的STH转换效率，而且显示了1.046％表现出超过10小时的高度长期稳定性。