Fabrication of Ultrafine Cu 2 O Nanoparticles on W 18 O 49 Ultra-Thin Nanowires by In-Situ Reduction for Highly Efficient Photocatalytic Nitrogen Fixation.

Photocatalytic ammonia synthesis technology is one of the important methods to achieve green ammonia synthesis. Herein, two samples of Cu ion-doped W 18 O 49 with different morphologies, ultra-thin nanowires (Cu-W 18 O 49 -x UTNW) and sea urchin-like microspheres (Cu-W 18 O 49 -x SUMS), are synthesized by a simple solvothermal method. Subsequently, Cu 2 O-W 18 O 49 -x UTNW/SUMS is synthesized by in situ reduction, where the NH 3 production rate of Cu 2 O-W 18 O 49 -30 UTNW is 252.4 µmol g -1  h -1 without sacrificial reagents, which is 11.8 times higher than that of the pristine W 18 O 49 UTNW. The Cu 2 O-W 18 O 49 -30 UTNW sample is rich in oxygen vacancies, which promotes the chemisorption and activation of N 2 molecules and makes the N≡N bond easier to dissociate by proton coupling. In addition, the in situ reduction-generated Cu 2 O nanoparticles exhibit ideal S-scheme heterojunctions with W 18 O 49 UTNW, which enhances the internal electric field strength and improves the separation and transfer efficiency of the photogenerated carriers. Therefore, this study provides a new idea for the design of efficient nitrogen fixation photocatalysis.