Defect-engineered WO3−x nanosheets for optimized photocatalytic nitrogen fixation and hydrogen production

Developing artificial N2 fixation and hydrogen production using mild, green, clean, and reliable sunlight is of great significance. In this study, the photocatalytic nitrogen fixation and hydrogen production performances of WO3−x were improved by oxygen vacancies engineering. WO3−x nanosheets with oxygen-rich defects were readily synthesized by hydrogen reduction treatment. WO3−x exhibits a two-dimensional nanosheets structure, and the introduction of oxygen defects affects its energy band structure. The slight narrowing of the band gap and the increase of the conduction band facilitate the transfer of photogenerated charges and increase the reducibility of WO3−x. Electron paramagnetic resonance (EPR) and N2-temperature programmed desorption (N2-TPD) prove that oxygen vacancies can regulate the adsorption and activation of N2 molecules. W500 specimen has a photocatalytic nitrogen fixation activity of 28.4 μmol g−1 h−1 and a hydrogen production activity of 60.4 μmol g−1 h−1 under the full spectrum. It is hoped that oxygen vacancies engineering can provide some inspiration for the rational design and optimization of efficient photocatalytic fixation of N2 and hydrogen production.