Regulating Cu Atom Dispersity on Nitrogen‐Doped Carbon for Boosting Electrocatalytic Nitrate Reduction in Strongly Acidic Media

Producing ammonia (NH₃) by nitrate reduction reaction (NO₃RR) under acidic conditions has considerable economic value, but there is still a lack of stable and efficient catalysts, due to the complex NO₃RR process, strongly competing hydrogen evolution reaction (HER), and highly corrosive environment. Herein, a series of Cu-based catalysts with different Cu atom dispersity on N-doped carbon are developed for acidic NO₃RR, where the Cu element can be controlled from single atoms to nanoparticles by tuning the pyrolysis temperature. The catalyst that contains both single atoms and nanoparticles exhibits the optimal electrocatalytic performance, achieving a maximal NH₃ Faraday efficiency of 98.6 % and a high NH₃ yield of 11.8 mg h^-1 cm^-2 at -0.3 V (vs. RHE) under a strongly acidic environment. Theoretical calculations combined with in-situ characterization techniques reveal that the coexistence of Cu single atoms and nanoparticles promotes the two-step relay catalysis, and that the interaction between nanoparticles and surrounding single atoms can optimize the intermediate adsorption, thus reducing the reaction energy barrier of the NO₃RR process and suppressing competing HER. This work highlights the effects of synergy between single atoms and nanoparticles on boosting tandem catalysis and provides a reasonable reference for developing acidic NO₃RR electrocatalysts.