Structurally Disordered RuO2 Nanosheets with Rich Oxygen Vacancies for Enhanced Nitrate Electroreduction to Ammonia

Electrochemical reduction of nitrate pollutants to ammonia has emerged as an attractive alternative for ammonia synthesis. Currently, many strategies have been developed for enhancing nitrate reduction to ammonia (NRA) efficiency, but the influence of the degree of structural disorder is still unexplored. Here, carbon-supported RuO2 nanosheets with adjustable crystallinity are synthesized by a facile molten salt method. The as-synthesized amorphous RuO2 displays high ammonia Faradaic efficiency (97.46 %) and selectivity (96.42 %), greatly outperforming the crystalline counterparts. The disordered structure with abundant oxygen vacancies is revealed to modulate the d-band center and hydrogen affinity, thus lowering the energy of the potential-determining step (NH2 *→NH3 *).