Developing photocathodes with a high photocurrent density and large onset potential is crucial for achieving solar driven water splitting. Herein, we report an efficient copper bismuth oxide (CuBi₂O₄) photocathode with a unique two-dimensional (2D) porous heterojunction structure. By designing a type II heterojunction structure with CuO, the resultant CuBi₂O₄/CuO photocathode exhibits a photocurrent density of 1.49 mA cm⁻² at 0.6 V_SHE, which is over 2 times that of the pristine CuBi₂O₄ photocathode. Further anodization treatment leads to an improved photocurrent density of 1.87 mA cm⁻² at 0.6 V_SHE, which is the highest photoresponse for CuBi₂O₄-based photocathodes. The synergistic effect of high surface area, short charge transfer distance in the 2D structure, efficient charge transfer and improved conductivity are the key reasons for the good performance of the CuBi₂O₄/CuO photocathodes. Moreover, the onset potential of the anodized CuBi₂O₄/CuO photocathode was over 1.1 V_SHE, enabling an unbiased photoelectrochemical water splitting process by combining with a BiVO₄ photoanode. This work highlights the good potential of CuBi₂O₄ in achieving a spontaneous overall water splitting process.

中文翻译：

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制作高效的异质结构CuBi ₂ O ₄光电阴极，实现无偏水分解†

开发具有高光电流密度和大起始电位的光电阴极对于实现太阳能驱动的水分解至关重要。在这里，我们报告了一种高效的具有独特的二维（2D）多孔异质结结构的氧化铜铋（CuBi ₂ O ₄）光电阴极。通过用CuO设计II型异质结结构，得到的CuBi ₂ O ₄ / CuO光电阴极在0.6 V _SHE下显示出1.49 mA cm ^-2的光电流密度，是原始CuBi ₂ O ₄光电阴极的2倍以上。进一步的阳极氧化处理导致0.6 V时光电流密度提高到1.87 mA cm ^-2_SHE是基于CuBi ₂ O ₄的光电阴极的最高光响应。高表面积，2D结构中较短的电荷转移距离，有效的电荷转移和提高的电导率的协同效应是CuBi ₂ O ₄ / CuO光电阴极良好性能的关键原因。此外，阳极氧化的CuBi ₂ O ₄ / CuO光电阴极的起始电位超过1.1 V _SHE，通过与BiVO ₄光电阳极结合使用，可以实现无偏光电化学水分解工艺。这项工作突出了CuBi ₂ O ₄的良好潜力。 实现自发的整体水分解过程。