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

Development of highly active and selective electrocatalysts for the reduction of nitrate (NO3–) to ammonia is critical for the production of green ammonia. Herein, we designed and synthesized NiMoO4 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 NO3– 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 NO3– reduction to NH3 reaction (NO3–RR). The optimized sample possessed excellent NO3–RR activity. An NH3–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 NO3–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 NO3–RR catalysts.