Ultrafast fabrication of nanostructure WO3 photoanodes by hybrid microwave annealing with enhanced photoelectrochemical and photoelectrocatalytic activities

Tungsten oxide (WO3) nanoplate films with a relatively rough surface were successfully fabricated via a simple hydrothermal method, followed by the hybrid microwave annealing (HMA) treatment only a few minutes for the first time. The microscopic morphology and phase were characterized by scanning electron microscopy (SEM), high resolution transmission electron microscopy (HR-TEM), Raman spectrum and X-ray diffraction (XRD). Photoelectrochemical measurements demonstrated that the obtained WO3 film of microwave processing for 11 min exhibited the photocurrent density of 1.60 mA/cm(2) at 1.2 V (vs. Ag/AgCl) and the IPCE value of 55% at 355 nm under an applied voltage of 1.0 V (vs. Ag/ AgCl), which were about 3 and 2.5 times compared with the WO3 film prepared by the conventional annealing method, respectively. Moreover, the WO3-HMA films were applied to the versatile photoanode-driven photoelectrochemical system for CO2 reduction into formic acid. The maximum formic acid generation rate and faradaic efficiency of the WO(3)HMA films were 9.21 mu mol h(-1) cm(-2) and 45.45%, respectively. This study provided a facial and rapid method to synthesize the high-performance WO3 photoanodes with better photoelectrochemical and photoelectrocatalytic activities. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.