The effect of the photochemical environment on photoanodes for photoelectrochemical water splitting

Besides photoelectrode materials, realizing the synergy of the photochemical environment and photoelectrodes for high charge carrier utilization is crucial for enhancing the performance of photoelectrochemical (PEC) water splitting systems. However, few researchers have focused on this important aspect. Herein, the effect of the photochemical environment on photoanodes in PEC water splitting, including the redox potential of electrolytes and light direction, is rationally discussed. A combined study of the potential distribution and electrochemical impedance spectroscopy reveals that the low redox potential of electrolytes facilitates the interior charge transfer and surface charge utilization by enlarging the depletion layer. In addition, it is found that the optimum thickness of semiconductors in photoelectrodes is the length of the depletion layer plus diffusion layer.