What’s the Key Factor to Ensure the Photoactivity Enhancement of Fe2O3 Films with Ni(OH)2 Loading: Clues from a Structural Modification with Flagella Nanowires

Abstract

A much higher photoactivity enhancement of Fe2O3 photoanode films was achieved by loading flagella-nanowire-modified Ni(OH)2 than by loading pure Ni(OH)2. Cyclic voltammetry curves and coupled i–t/potential step chronoamperometry measurements under super band gap irradiation revealed a much heavier hole accumulation in a pure Ni(OH)2 layer. Electrochemical impedance and coupled i–t/open circuit potential transient measurements were applied to explore the dynamics of hole transfer through the Fe2O3|Ni(OH)2|electrolyte multiple interface systems, finding that the structural modification of Ni(OH)2 with flagella nanowires can speed up the charge transfer at both the Fe2O3|Ni(OH)2 and Ni(OH)2|electrolyte interfaces. Based on a recent discovery that the ion-permeable Ni(OH)2 electrocatalyst acts as a surface-attached redox system, a theoretical model was proposed to explain the influence of hole accumulation in Ni(OH)2 layer on the photoactivity of Fe2O3 films. The outcome of this work implies that the key fac...