Preventing Nitrite Desorption via Switching Hydrogenation Position: A Dual-Site Approach for Selective Nitrate...

The electrochemical nitrate reduction reaction (NO₃RR), which converts harmful nitrates into valuable ammonia (NH₃) with zero carbon emission, is one of the most promising alternatives to the Haber-Bosch process. However, the NO₃RR process is complex and involves multiple proton-coupled electron transfers that generate intermediates or byproducts, such as NO₂ ^-, resulting in low ammonia yields and faradaic efficiency (FE). Herein, by constructing a FeCu bimetallic catalyst (FeCu-NC), the hydrogenation position of *NO₃ is switched at the FeCu dual-atom site, preventing the desorption of *NO₂ intermediate. Furthermore, electron transfer from Cu to Fe sites mimics the electron flow direction in natural nitrite reductase enzymes and accelerates the reduction of *NO₂ to NH₃, achieving efficient conversion of NO₃ ^- to NH₃. A 24-hour electrocatalytic experiment with FeCu-NC demonstrates negligible NO₂ ^- formation throughout the NO₃RR process, with an ammonia production rate of 6.13 mg h^-1 mg_cat ^-1 and an impressive FE of 95%, which are remarkably superior in comparison to most of the NO₃RR electrocatalysts. This work opens new avenues for the fundamental understanding of catalytic mechanisms and the development of next-generation catalysts for sustainable ammonia production.