N-bridge anchored asymmetric AgCu dual-atomic catalysts on MXene for efficient nitrate reduction

Electrocatalytic nitrate reduction reaction (NO₃RR) offers a promising route for sustainable ammonia synthesis and wastewater treatment, yet designing highly active and selective catalysts remains challenging. Herein, we construct an N-bridge anchored asymmetric AgCu dual-atomic catalyst (DAC) on Ti₃C₂T_x MXene (AgCu DAC/Ti₃C₂T_x) for efficient nitrate electroreduction. The unique N-bridged structure stabilizes the asymmetric AgCu dual sites, enabling synergistic adsorption and activation of nitrate intermediates. In situ X-ray absorption fine structure (XAFS) spectroscopy confirms the dynamic evolution of the Ag–Cu coordination under reaction conditions, revealing their maintained heteronuclear pairing and electronic coupling during NO₃RR. As a result, the AgCu DAC/Ti₃C₂T_x catalyst achieves a high NH₃ Faradaic efficiency of ~ 97.1% with an exceptional yield rate of ~ 3.1 mg·h⁻¹·cm⁻² at −0.5 V vs. reversible hydrogen electrode (RHE), surpassing most reported dual-atom catalysts. This work provides insights into the design of asymmetric dual-atomic sites for multi-step catalytic reactions.