Modulation of Reactive Hydrogen Adsorbed on Dual-Active Site NiMoO₄ Nanocubes for Reduction of Nitrate to Ammonia

Abstract

Development of highly active and selective electrocatalysts for the reduction of nitrate (NO 3 − ) to ammonia is critical for the production of green ammonia. Herein, we designed and synthesized NiMoO 4 nanocubes as an efficient electrocatalyst for nitrate reduction using deep eutectic solvents (DESs) as synthesis media. By constructing Mo and Ni dual-active sites, Mo facilitates NO 3 − adsorption/association, and Ni acts as an active hydrogen (*H) donating center. The amount and destination of *H can be regulated, which can effectively enhance the activity of the NO 3 − reduction to NH 3 reaction (NO 3 − RR). The optimized sample possessed excellent NO 3 − RR activity. An NH 3 −N selectivity of up to 96.94% and a Faraday efficiency of up to 96.13% can be achieved at −0.4 V in a neutral solution. The catalytic NO 3 − RR mechanism was also investigated by density functional theory (DFT) calculations. This dual-active site electrocatalyst provides an alternative idea for the synthesis and application of high-performance NO 3 − RR catalysts.