Ta₃N₅ is a promising photoanode material with a theoretical maximum solar conversion efficiency of 15.9% for photoelectrochemical water splitting. However, the highest applied bias photon-to-current efficiency achieved so far is only 2.72%. To bridge the efficiency gap, effective carrier management strategies for Ta₃N₅ photoanodes should be developed. Here, we propose to use gradient Mg doping for band structure engineering and defect control of Ta₃N₅. The gradient Mg doping profile in Ta₃N₅ induces a gradient of the band edge energetics, which greatly enhances the charge separation efficiency. Furthermore, defect-related recombination is significantly suppressed due to the passivation effect of Mg dopants on deep-level defects and, more importantly, the matching of the gradient Mg doping profile with the distribution of defects within Ta₃N₅. As a result, a photoanode based on the gradient Mg-doped Ta₃N₅ delivers a low onset potential of 0.4 V versus that of a reversible hydrogen electrode and a high applied bias photon-to-current efficiency of 3.25 ± 0.05%.

Ta ₃ N ₅是一种有前途的光阳极材料，其理论上最大的太阳能转化效率为15.9％。但是，到目前为止，所达到的最高施加偏压光子-电流效率仅为2.72％。为了弥合效率差距，应该为Ta ₃ N _5光阳极开发有效的载流子管理策略。在这里，我们建议使用梯度Mg掺杂进行能带结构工程和Ta ₃ N _5的缺陷控制。Ta ₃ N _5中的梯度Mg掺杂分布引起能带边缘能量的梯度，从而大大提高了电荷分离效率。此外，由于Mg掺杂剂对深层缺陷的钝化作用，更重要的是，梯度Mg掺杂分布与Ta ₃ N ₅内缺陷分布的匹配，显着抑制了与缺陷有关的重组。结果，与可逆氢电极相比，基于梯度Mg掺杂的Ta ₃ N ₅的光阳极提供0.4 V的低启动电位，并提供3.25±0.05％的高施加偏压光子-电流效率。