Optimization of electrolyte to significantly improve photoelectrochemical water splitting performance of ZnO nanowire arrays

In this work, a simple and facile strategy has been applied to improve the photoelectrochemical (PEC) water splitting performance of ZnO nanowire arrays by the optimization of Na2SO4 and Na2SO3 electrolytes. The ZnO nanowire array electrode exhibits significant PEC water splitting enhancement in Na2SO3 electrolyte solution compared to in Na2SO4 electrolyte solution. The photocurrent density of znO nanowire array photoanode in Na2SO3 electrolyte solution is 6 times higher than that in Na2SO4 electrolyte solution at 0.5 V vs. Ag/AgCl. Mott Schottky (MS) and electrochemical impedance spectroscopy (EIS) studies of ZnO nanowire array electrodes in Na2SO4 and Na2SO3 electrolyte solutions reveal that SO32- anions consume the holes and efficiently improve the separation of photogenerated electron-hole pairs, leading to significant improvement for PEC water splitting performance in Na2SO3 electrolyte solution. This work provides a promising strategy to improve the PEC water splitting performance of photoanode materials by the optimization of electrolytes.