Uniform NiP_x nanospheres loaded onto defective H_xWO_3-y with three-dimensionally ordered macroporous structure for photocatalytic nitrogen reduction

Ammonia synthesis from N₂ and water can be achieved at mild conditions utilizing photocatalysis, however the high activation energy for nitrogen coupled with low electron-hole separation efficiency in the photocatalyst results in a low rate of ammonia generation. In this work, a three-dimensional ordered macroporous structure (3DOM) H_xWO_3-y with oxygen vacancies was constructed, which promoted the activation of nitrogen and increased charge carrier separation, thus improving the photocatalytic nitrogen reduction ability with a value of 7.4 μmol g⁻¹ h⁻¹. The nitrogen reduction ability of 3DOM H_xWO_3-y was further improved to 34 μmol g⁻¹ h⁻¹ by loading NiP_x nanospheres onto the 3DOM structure, which is ∼5 times than 3DOM H_xWO_3-y. DFT analysis revealed that the oxygen vacancies in H_xWO_3-y showed higher adsorption activation ability of N₂ with the nitrogen reduction reaction (NRR) proceeding in a symmetrical alternating pathway. This study offers a promising route for the N₂ fixation using solar energy.