High-ammonia selective metal–organic framework–derived Co-doped Fe/Fe(2)O(3) catalysts for electrochemical nitrate reduction

Ammonia (NH(3)) is an ideal carbon-free power source in the future sustainable hydrogen economy for growing energy demand. The electrochemical nitrate reduction reaction (NO(3)(−)RR) is a promising approach for nitrate removal and NH(3) production at ambient conditions, but efficient electrocatalysts are lacking. Here, we present a metal–organic framework (MOF)–derived cobalt-doped Fe@Fe(2)O(3) (Co-Fe@Fe(2)O(3)) NO(3)(−)RR catalyst for electrochemical energy production. This catalyst has a nitrate removal capacity of 100.8 mg N g(cat)(−1) h(−1) and an ammonium selectivity of 99.0 ± 0.1%, which was the highest among all reported research. In addition, NH(3) was produced at a rate of 1,505.9 μg h(−1) cm(−2), and the maximum faradaic efficiency was 85.2 ± 0.6%. Experimental and computational results reveal that the high performance of Co-Fe@Fe(2)O(3) results from cobalt doping, which tunes the Fe d-band center, enabling the adsorption energies for intermediates to be modulated and suppressing hydrogen production. Thus, this study provides a strategy in the design of electrocatalysts in electrochemical nitrate reduction.