Synthesis of reduced cubic phase WO3−xnanosheet by direct reduction of H2WO4·H2O

The cubic phase WO3−xwith two-dimensional nanosheet structure is prepared at a relative low temperature through thermal decomposition method. The starting material and decomposition environment are the key factors to obtain the cubic phase WO3−x. The cubic crystal structure is stabilized by the large amounts of oxygen vacancies. The dark blue cubic WO3−xexhibits electrocatalysis performance for hydrogen evolution reaction (HER) in acidic solution (an overpotential −294 mV at the current density of 10 mA/cm2). The cubic phase WO3−xshows good photothermal stability with eminent photothermal conversion effect (photothermal conversion efficiency is 48.7% at 808 nm).