Active Hydrogen-Switchable Dynamic Oxygen Vacancies in MoO<sub>3–<i>x</i></sub> upon Ru Nanoparticle Decoration for Boosting Photocatalytic Ammonia Synthesis Performance
Lulu Zhang, Rui Li, Lijun Guo, Luyao Cui, Xiaochao Zhang, Yawen Wang, Yunfang Wang, Xuan Jian, Xiaoming Gao, Caimei Fan, Jiancheng Wang, Jianxin Liu
Abstract
Simultaneous promotion of N 2 adsorption and NH 3 desorption, which is referred to as breaking the scaling relationship, is a major challenge in the photocatalytic ammonia synthesis reaction. Herein, we have successfully developed an active hydrogen (H*)-switchable dynamic oxygen vacancy (OV) evolution strategy for solving this problem on MoO 3– x decorated by Ru nanoparticles (Ru/MoO 3– x ). In this strategy, H* drives the cyclic dynamic evolution of the OVs between the initial state Ru/MoO 3– x and intermediate state Ru/MoO 3– x N y, which exhibit strong capabilities for N 2 adsorption and NH 3 desorption, respectively. The combination of in situ characterization and DFT calculation reveals that the strong interaction between N 2 and OVs in Ru/MoO 3– x induces the spontaneous formation of Ru/MoO 3– x N y, whereas this nitrogen species filling the OVs promotes the H* spillover from Ru to MoO 3– x, thereby accelerating the hydrogenation of lattice N and the desorption of NH 3 . As a result, the 6.5 wt % Ru/MoO 3– x achieves an ammonia production rate of 192.38 μmol·g –1 ·h –1, 2.68-fold higher than that of pristine MoO 3– x . Besides, nitrate reduction and nitric oxide reduction to synthesize NH 3 further verified this strategy, which exhibited a performance of 370 and 220 μmol·g –1 ·h –1, respectively. This study opens an avenue for a catalytic reaction with scaling relationship.