Enhanced Visible Light Activity of Single-Crystalline WO3 Microplates for Photoelectrochemical Water Oxidation

Abstract

The preparation of metal oxides on a conductive substrate has been an important issue for improving photo electrochemical water splitting efficiency. In this work, a facile synthetic process is reported for single-crystalline WO3 microplates with variable thicknesses grown directly on a fluorine-doped tin oxide substrate followed by an annealing procedure. The WO3 microplate electrode showed an improved photocurrent under 1 sun irradiation (1.9 mA/cm(2) at 0.6 V vs Ag/AgCl, 100 mW/cm(2)) for water oxidation, including a significant enhancement in the visible light region compared to either a nanoparticle or a bulk film electrode. The enhanced water oxidation activity originates from both the single crystallinity with an optimum thickness and the oxygen-deficient characteristic of the WO3 microplates. To improve the photochemical stability, FeOOH electrocatalysts were deposited on the surfaces of the WO3 microplates. The resulting WO3/FeOOH composite electrode showed enhanced stability for water oxidation reactions