Constructing asymmetric active sites on defective Ru/W18O49 for photocatalytic nitrogen fixation

Abstract

Defect engineering can offer active sites for N₂ adsorption and activation due to the abundant localized electrons of surface defects. However, the high energy barriers of the defect band can restrict the electron transfer, which thus limits the photocatalytic N₂ fixation performance. Herein, we demonstrate that Ru/W₁₈O₄₉ exhibits a nearly 6-fold enhanced photocatalytic activity for ammonia production under visible irradiation compared with pristine W₁₈O₄₉. Our investigations reveal that the enhanced photocatalytic N₂ fixation activities are mainly attributed to the synergistic effect of oxygen vacancies and Ru modification. The decorated Ru species can modify the coordination structure of oxygen vacancies by forming Ru–O–W bonds. The Ru–O–W centers can serve as active sites for the side-on adsorption of N₂ due to their asymmetric polarization, better promoting the electron transfer to absorbed N₂. Moreover, the LSPR between Ru and oxygen vacancies provides sufficient electrons for N₂ activation. As a result, the efficient electron transfer facilitates the activation and dissociation of N₂ on Ru/W₁₈O₄₉, which is feasible for the reduction of N₂ to NH₃. This work provides a promising strategy for enhanced photocatalytic N₂ fixation by modulating defect engineering.