Intermittent electrolysis enabling enhanced efficiency and stability for nitrate reduction

LM Wu and LB Zhang and JQ Feng and SH Jia and RH Wang and XN Song and XD Ma and QG Zhu and XC Kang and QL Qian and XF Sun and BX Han, CHEM, 11, 102591 (2025).

DOI: 10.1016/j.chempr.2025.102591

Catalyst deactivation is a common issue in catalysis, which restricts its practical applications. Nitrate electroreduction using copper (Cu) catalysts offers an eco-friendly NH3 production route. However, the NH3 selectivity and activity decline significantly due to Cu surface reconstruction and compositional changes during electrolysis. Herein, an intermittent reduction strategy is proposed to maintain high efficiency and stability of Cu2O for NO3 to NH3 through applying an alternating on/off electrolysis. The high Faradaic efficiency (FE) (>= 90%) and current density (>= 110 mA cm-2) were maintained at least 200 h, which improved the cycle stability by 40 times compared with relay electrolysis. Detailed experimental studies and theoretical calculations manifest that the composition and structure of Cu catalyst could be recovered periodically via intermittent electrolysis, which facilitated NO3-adsorption, moderated *NO2 coverage, and balanced *H production/ consumption, leading to high selectivity toward NH3 in long-term electrolysis. Further investigation showed that this strategy could also be extended to other Cu-based catalysts.

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