Ordered mesoporous WO2.83: selective reduction synthesis, exceptional localized surface plasmon resonance and enhanced hydrogen evolution reaction activity

Oxygen vacancy engineering is an important tool to vary the properties of functional transition metal oxides; however, the selective synthesis of their sub-stoichiometric oxides with a defined composition and electronic configuration is still challenging. Here we describe a rational protocol to prepare mesoporous sub-stoichiometric WO2.83 through controlled oxygen vacancy formation in mesoporous WO3. Different from bulk WO3, the use of a mesoporous WO3 not only greatly decreases the H2 reduction temperature, but also causes reduction to WO2.83 with high selectivity. Oxygen vacancies enable exceptional plasmon resonance in mesoporous WO2.83, which further could be tailored in a wide range through redox chemistry. Furthermore, mesoporous WO2.83 exhibits superior hydrogen evolution reaction activity compared to pristine mesoporous WO3, and it can be shown that the HER activity is crucially dependent on the amount of oxygen vacancies.