Li-intercalation boosted oxygen vacancies enable efficient electrochemical nitrogen reduction on ultrathin TiO2 nanosheets

Abstract

Electrochemical nitrogen reduction reaction (NRR) paints a magnificent blueprint for NH3 synthesis by a carbon-neutral and environmentally-benign route. However, great challenges remain in the improvement of the activity and selectively of conventional NRR electrocatalysts. Herein, we report a Li-intercalation strategy into TiO2 nanosheets to boost oxygen vacancy (VO) concentration, activating the inert TiO2(B) into efficient Li-TiO2(B) electrocatalysts for NRR. Li-TiO2(B) exhibits an outstanding NRR performance with an NH3 yield of 8.7 μg h−1 mg–1cat. and Faradaic efficiency (FE) of 18.2 % at –0.4 V vs. RHE, which is 6 times that of the pristine TiO2(B) counterpart. Experimental results reveal that the increased VO contributes good conductivity and facilitates the charge transfer, while density functional theory (DFT) computations suggest that the increased VO provides more active sites for N2 adsorption/activation, and favors the subsequent NRR kinetics, leading to Li-intercalated TiO2(B) nanosheets with superior electrocatalytic performance to pristine TiO2(B).