The holes transfer efficiency is a key issue in the process of photoelectrocatalytic water splitting. Here, we found that the oxygen concentration and distribution in hematite evidently affected the bulk and surface holes transfer, and thus influenced the performance of photoelectrocatalytic water splitting. Two macro-changes on oxygen were observed during the thermal treatment. The first-stage led to a lower bulk O/Fe ratio of only 1/1 and the generation of adsorbed oxygen, obtaining porous nanorods (NRs) with a ~1.4 nm FeO_x layer. Bulk charge recombination centers and surface deep traps caused a lower bulk and surface charge transfer. The second-stage led to a bulk O/Fe ratio of nearly 3/2 and single high crystallization NRs. Major increases in charge transfer constant from 0.27 to 4.5 s⁻¹ and in photocurrent density (vs.1.23 V_RHE) from 0.0235 to 1.20 mA/cm² were observed, which demonstrates the higher holes transfer efficiency. Furthermore, the connection of oxygen migration and charge transfer was derived. This work could provide effective guidance for further optimization of semiconductor photoanodes.

空穴传输效率是光电催化水分解过程中的关键问题。在这里，我们发现赤铁矿中的氧气浓度和分布明显影响了本体和表面空穴的转移，从而影响了光电催化水分解的性能。在热处理过程中，观察到氧的两个宏观变化。第一阶段导致较低的本体O / Fe比仅为1/1，并产生了吸附的氧气，从而获得了具有〜1.4 nm FeO _x层的多孔纳米棒（NRs）。体电荷复合中心和表面深陷阱导致较低的体电荷和表面电荷转移。第二阶段导致大体O / Fe比接近3/2和单个高结晶NR。电荷转移常数从0.27大幅增加到4.5 s ^-1并且在0.0235至1.20mA / cm ^2的光电流密度（vs.1.23V _RHE）中观察到，这表明更高的空穴传输效率。此外，得出了氧迁移和电荷转移的关系。这项工作可以为进一步优化半导体光阳极提供有效的指导。