Promoting the hydrogen spillover via dual active sites synergistically for efficient photo-driven nitrogen fixation

Abstract

Photocatalytic ammonia synthesis is heralded as the most promising field that will certainly gain increasing attention as a sustainable strategy for low-carbon NH3 production and H2 storage. However, one great challenge is to design ideal catalysts, which can provide the energetic active sites for nitrogen activation and hydrogen dissociation at the same time. In this study, we report that efficient photo-driven ammonia synthesis can be realized by synergetic effect of abundant Mo (V) species and Pt under ambient conditions. More specifically, the optimized Pt-loaded MoO3-x photocatalyst has attained the superior NH3 production rates of 3456μg·g-1·h-1 under visible light irradiation (≥400nm). As evidenced experimentally and theoretically, the enhanced photocatalytic performance can be ascribed to dual-active sites, where the loaded Pt co-catalyst can boost hydrogen spillover from Pt to MoO3-x induced by OV due to the low barrier of H⁎ migration between hydrogen activation sites (Pt-O bridge) and nitrogen activation sites (low-valence Mo species), further increasing the number of Mo (V) active sites. And Mo (V) species adjacent oxygen vacancy with outstanding electron-donating capability and strong nitrogen chemisorption played a crucial role in facilitating nitrogen dissociation. Therefore, synergizing abundant Mo (V) species and loaded-Pt can optimize the photo-driven nitrogen reduction and hydrogen oxidation. This work provides a new idea for the rational design of efficient photo-driven ammonia synthesis.