The photoelectrochemical (PEC) water reduction performance of CuBi₂O₄ (CBO)-based photocathodes is still far from their theoretical values due to low bulk and surface charge separation efficiencies. Herein, we propose a regrowth strategy to prepare a photocathode with CBO coating on Zn-doped CBO (CBO/Zn-CBO). Furthermore, NaBH₄ treatment of CBO/Zn-CBO introduced oxygen vacancies (O_v) on CBO/Zn-CBO. It was found that Zn-doping not only increases the charge carrier concentration of CBO, but also leads to appropriate band alignment to form homojunctions. This homojunction can effectively promote the separation of electron–hole pairs, thus obtaining excellent photocurrent density (0.5 mA cm⁻² at 0.3 V vs. RHE) and charge separation efficiency (1.5 times than CBO). The following surface treatment induced O_v on CBO/Zn-CBO, which significantly increased the active area of the surface catalytic reaction and further enhanced the photocurrent density (0.6 mA cm⁻²). In the absence of cocatalysts, the electron injection efficiency of O_v/CBO/Zn-CBO was 1.47 times improved than that of CBO. This work demonstrates a homojunction photocathode with O_v modulation, which provides a new view for future photoelectrochemical water splitting.

中文翻译：

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氧空位调制的同质结结构CuBi2O4光电阴极，可有效减少太阳能。

由于低的体积和表面电荷分离效率，基于CuBi ₂ O ₄（CBO）的光电阴极的光电化学（PEC）减水性能仍远未达到其理论值。在这里，我们提出了一种再生策略，以在掺锌的CBO（CBO / Zn-CBO）上制备带有CBO涂层的光电阴极。此外，CBO / Zn-CBO的NaBH ₄处理在CBO / Zn-CBO上引入了氧空位（O _v）。发现Zn掺杂不仅增加了CBO的载流子浓度，而且导致适当的能带对准以形成同质结。该同质结可以有效地促进电子-空穴对的分离，从而获得出色的光电流密度（0.3 V时为0.5 mA cm ^-2）相对于RHE）和电荷分离效率（是CBO的1.5倍）。随后的表面处理在CBO / Zn-CBO上诱导O _v，这显着增加了表面催化反应的活性面积，并进一步提高了光电流密度（0.6 mA cm ^-2）。在没有助催化剂的情况下，O _v / CBO / Zn-CBO的电子注入效率是CBO的1.47倍。这项工作表明带O同质结光电_v调制，这为未来的光电化学分解水的新观点。