Photoelectrochemical Water Oxidation Efficiency of a Core/Shell Array Photoanode Enhanced by a Dual Suppression Strategy

The development of earth-abundant semiconductor photoelectrodes is of great importance to high-efficiency and sustainable photoelectrochemical water splitting. Herein, a one-dimensional TiO2 array photoanode was sheathed with an ultrathin overlayer of phosphated nickel-chromium double-metal hydroxide by a photoassisted modification and deposition strategy. The core/shell array photoanode resulted in a large cathodic shift of photocurrent onset potential (≈200 mV). Nearly 100 % oxidative efficiency for PEC water oxidation was achieved over a wide range of potential. Mechanism studies show that the modification of phosphate leads to significantly improved charge separation. The amorphous hydroxide sheath could efficiently inhibit oxygen reduction reactions. Therefore, this strategy enables the simultaneous suppression of surface carrier recombination and back reactions, which is promising to improve the water oxidation efficiency of currently prevailing photoanodes.