Although large research efforts have been devoted to photoelectrochemical (PEC) water splitting in the past several decades, the lack of efficient, stable and Earth-abundant photoelectrodes remains a bottleneck for practical application. Here, we report a photocathode with a coaxial nanowire structure implementing a Cu₂O/Ga₂O₃-buried p–n junction that achieves efficient light harvesting across the whole visible region to over 600 nm, reaching an external quantum yield for hydrogen generation close to 80%. With a photocurrent onset over +1 V against the reversible hydrogen electrode and a photocurrent density of ~10 mA cm⁻² at 0 V versus the reversible hydrogen electrode, our electrode constitutes the best oxide photocathode for catalytic generation of hydrogen from sunlight known today. Conformal coating via atomic-layer deposition of a TiO₂ protection layer enables stable operation exceeding 100 h. Using NiMo as the hydrogen evolution catalyst, an all Earth-abundant Cu₂O photocathode was achieved with stable operation in a weak alkaline electrolyte. To show the practical impact of this photocathode, we constructed an all-oxide unassisted solar water splitting tandem device using state-of-the-art BiVO₄ as the photoanode, achieving ~3% solar-to-hydrogen conversion efficiency.

尽管在过去的几十年中，人们一直致力于光电化学（PEC）水的分解研究，但是缺乏高效，稳定和富含地球的光电极仍然是实际应用的瓶颈。在这里，我们报道了一种具有同轴纳米线结构的光电阴极，该结构实现了Cu ₂ O / Ga ₂ O ₃埋入的p–n结，可在整个可见光区域内有效收集超过600 nm的光，从而达到产生氢的外部量子产率接近80％在可逆氢电极上发生超过+1 V的光电流，并且光电流密度为〜10 mA cm ^-2与可逆的氢电极相比，在0 V时，我们的电极构成了当今已知的最好的氧化物光电阴极，用于催化由太阳光产生的氢。通过原子层沉积的TiO ₂保护层进行的保形涂层可实现超过100小时的稳定运行。使用NiMo作为析氢催化剂，可以在弱碱性电解质中稳定运行，从而获得全地球丰富的Cu ₂ O光电阴极。为了显示该光电阴极的实际影响，我们使用最先进的BiVO ₄作为光电阳极，构建了一种全氧化物的无辅助太阳能分水串联装置，实现了约3％的太阳能转换效率。