Simultaneously Tuning Charge Separation and Surface Reaction in a Fe2O3 Photoanode for Enhanced Photoelectrochemical Water Oxidation

Abstract Photoelectrochemical (PEC) water splitting has gained intensive attention owing to its capability of converting solar energy into chemical fuel, that is, hydrogen. However, the PEC efficiency is severely limited by the recombination of charge carriers and slow kinetics of surface water oxidation. The exploration of efficient photoanodes is, thus, urgently demanded. Herein, a bilateral charge modulation strategy for an improved Fe 2 O 3 photoanode is reported. Z‐scheme Fe 2 O 3 ‐g‐C 3 N 4 heterojunction is first prepared with the aim of promoting the charge separation, followed by the electrodeposition of a NiFe‐based layered double hydroxide (LDH) on it in order to concurrently slow down the hole accumulation on the electrode surface and catalyze the water oxidation. The fabricated NiFe‐LDH@Fe 2 O 3 ‐g‐C 3 N 4 electrode exhibits an enhanced photocurrent density of 0.29 mA cm −2 at 1.23 V RHE , which is almost five times that of the pristine Fe 2 O 3 (0.06 mA cm −2 ). This work provides an appealing maneuver for improving water oxidation performance in semiconductor‐based PEC systems.