The efficiency of an electrode in photoelectrochemical (PEC) water splitting is determined by the light absorption efficiency, charge separation efficiency, and charge injection efficiency (η = η_absorption × η_separation × η_injection). Here, doping with Mn element and coating with NiFe layered double hydroxide (NiFe-LDH) have been applied to enhance the charge separation efficiency and charge injection efficiency of α-Fe₂O₃ as a water oxidation catalyst in the PEC water splitting process. The Mn doping improves the charge separation efficiency from 20% to 35% at high potential. The coating amount of NiFe-LDH, which can be controlled by hydrothermal conditions, has a significant effect on the performance of α-Fe₂O₃. At low precursor concentrations, the formed thin NiFe-LDH has little effect on the light absorption of α-Fe₂O₃, while NiFe-LDH fabricated at high precursor concentrations forms a thick layer that affects the light absorption of α-Fe₂O₃. The thin NiFe-LDH layer shifts the onset potential negatively and enhances the charge injection efficiency to 90% at high potential.