There is an urgent need for new materials that can catalyze or drive the photoelectrochemical (PEC) conversion of solar energy into chemical energy, i.e. solar fuels. Copper bismuth oxide (CBO) is a promising photocathode material for the photochemical reduction of water. Here, we systematically control the stoichiometry of CBO thin films prepared by reactive, direct-current magnetron co-sputtering from metallic Bi and Cu targets. The intrinsic photophysical and PEC material properties are investigated and evaluated in order to determine the optimum composition for hydrogen formation. Changing the stoichiometry of the films reveals a dramatic change in the optical band gap and crystal structure of CBO. The largest photocurrent density was achieved for a copper-to-bismuth ion ratio of 0.53, close to the CuBi 2 O 4 stoichiometry, which yielded J ph = − 0.48 mA cm −2 at 0 V RHE (RHE = reversible hydrogen electrode). Th...

中文翻译：

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磁控溅射铜氧化铋光电阴极用于太阳能减水

迫切需要能够催化或驱动将太阳能光化学（PEC）转换为化学能的新材料，即太阳能。氧化铜铋（CBO）是用于光化学还原水的一种有前途的光阴极材料。在这里，我们系统地控制了从金属Bi和Cu靶材通过反应性直流磁控共溅射制备的CBO薄膜的化学计量。为了确定形成氢的最佳组成，对固有的光物理和PEC材料性能进行了研究和评估。改变膜的化学计量比揭示了CBO的光学带隙和晶体结构的巨大变化。当铜铋离子比为0.53时，获得了最大的光电流密度，接近化学计量比的CuBi 2 O 4。其在0 V RHE（RHE =可逆氢电极）时产生J ph =-0.48 mA cm -2。那个...