Nanotube array-like WO3/W photoanode fabricated by electrochemical anodization for photoelectrocatalytic overall water splitting

Abstract Photoactive WO3 is attractive as a photocatalyst for green energy evolution through water splitting. In the present work, an electrochemical anodic oxidation method was used to fabricate a photo-responsive nanotube array-like WO3/W (NA-WO3/W) photoanode from W foil as a precursor. Compared with a reference commercial WO3/W electrode, the NA-WO3/W photoanode exhibited enhanced and stable photoelectrocatalytic (PEC) activity for visible-light-driven water splitting with a typical H2/O2 stoichiometric ratio of 2:1 and quantum efficiency of approximately 5.23% under visible-light irradiation from a light-emitting diode (λ = 420 nm, 15 mW/cm2). The greatly enhanced PEC performance of the NA-WO3/Wphotoanode was attributed to its fast electron–hole separation rate, which resulted from the one-dimensional nanotube array-like structure, high crystallinity of monoclinic WO3, and strong interaction between WO3 and W foil. This work paves the way to a facile route to prepare highly active photoelectrodes for solar light transfer to chemical energy.