Copper bismuthate (CuBi₂O₄, CBO) has attracted attention as a promising photocathode material for photoelectrochemical (PEC) water-splitting because of its small bandgap (1.6–1.8 eV), high internal photovoltage, and moderate stability in aqueous media. Herein, we report a novel solution synthesis method to fabricate bulky crystalline CBO photocathodes via an evaporation decomposition controlled process. The CBO photocathode synthesized under optimal conditions exhibited a uniform, dense film with intimate substrate contact and large-grains, allowing an enhanced charge transport and photocurrent stability in comparison to porous CBO counterparts. Consequently, the dense CBO achieved a photocurrent density of − 1.16 mA/cm² at 0.4 V versus the reversible hydrogen electrode (RHE) without a scavenger addition under simulated sunlight irradiation (AM 1.5 G, 100 mW/cm²). Significantly, the coupling of the CBO with a cupric oxide (CuO) underlayer and a Pt electrocatalyst increased the photocurrent density further to − 2.8 and − 3.5 mA/cm² at 0.4 V versus RHE, respectively, which is the highest value to date among all reported CBO based photocathodes.

铋酸铜（CuBi ₂ O ₄，CBO）由于其带隙小（1.6-1.8 eV），高内部光电压和在水介质中的中等稳定性而作为一种有前景的光电化学分解光电阴极材料备受关注。在这里，我们报告了一种新颖的溶液合成方法，通过蒸发分解控制过程来制造大体积的晶体CBO光电阴极。在最佳条件下合成的CBO光电阴极显示出均匀，致密的膜，具有紧密的基材接触和大晶粒，与多孔CBO对应物相比，可以增强电荷传输和光电流稳定性。因此，致密的CBO的光电流密度为− 1.16 mA / cm ²相对于可逆氢电极（RHE）在0.4 V下，在模拟阳光照射下（AM 1.5 G，100 mW / cm ²），没有添加清除剂。值得注意的是，CBO与氧化铜（CuO）底层和Pt电催化剂的偶合使光电流密度在相对于RHE的0.4 V下分别进一步提高至-2.8和-3.5 mA / cm ²，这是迄今为止的最高值所有报道的基于CBO的光电阴极。