Disordered layers on WO ₃ nanoparticles enable photochemical generation of hydrogen from water

Tailored defects on a semiconductor surface can provide active catalytic sites and effectively tune the electronic structure for suitable optical properties. Herein, we report that surface modification of WO ₃ with a disordered layer enables the photochemical hydrogen production from water. A simple room temperature solution process with lithium-ethylenediamine (Li-EDA) alters the surface of WO ₃ with localized defects that form a thin disordered layer. Both structural and optical characterization reveal that such a disordered layer induces an upshift in the Fermi level and the elevation of the conduction band of WO ₃ above the hydrogen reduction potential. Using an alkaline sacrificial agent, Li-EDA treated WO ₃ shows a co-catalyst-free photochemical hydrogen evolution rate of 94.2 μmol g ^-1 h ^-1 under simulated sunlight. To the best of our knowledge, this is the first example of using WO ₃ as a direct photocatalyst for hydrogen generation from water via simple surface defect engineering.