Engineering oxygen vacancies and low-valent bismuth at the surface of Bi2MoO6 nanosheets for boosting electrocatalytic N2 reduction

Abstract

Electrochemical nitrogen reduction reaction (NRR) is considered as an alternative to industrial Haber-Bosch N2 fixation process. Herein, an iodide ion assisted one-step hydrothermal method was developed to prepare Bi2MoO6 nanosheets with oxygen vacancies (OVs) and low-valent bismuth at the surface. The introduction of OVs makes Bi2MoO6 nanosheets possess rich unsaturated coordination surface atoms, and enhances the conductivity and N2 adsorption. Low-valent bismuth with 6p orbits reinforces the interaction with N2 via π back-donation. The high-efficiency adsorption and protonation of N2 over OVs-Bi2MoO6 catalyst was confirmed by N2 in-situ DRFTIR spectra and temperature-programmed-desorption. The obtained OVs-Bi2MoO6 nanosheets accomplished a favorable ammonia yield of ∼24.38 μg·mg−1h − 1 and a high Faradaic efficiency of 14.1% at −0.3 V in 0.1 M HCl solution. A feasible OVs assisted π back-donation mechanism was proposed for the enhanced NRR catalytic activity on OVs-Bi2MoO6 catalyst.