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

Significance Electrochemical reduction of nitrate pollution in water into value-added ammonium is essential for modern agriculture and industry and represents a potentially sustainable strategy to replace the traditional Haber–Bosch process. However, the nitrate reduction reaction (NO 3 − RR) process under ambient conditions often suffers from low selectivity. Here, we developed a strategy of tuning an electronic structure for preparing cobalt-doped Fe@Fe 2 O 3 electrocatalysts. Cobalt doping tunes the Fe d-band center, thereby modulating the adsorption energies of intermediates and suppressing hydrogen production. Therefore, the electrocatalysts exhibit superior NO 3 − RR activity with a high nitrate removal capacity (100.8 mg N g cat −1 h −1 ), NH 3 selectivity (99.0 ± 0.1%), and faradaic efficiency (85.2 ± 0.6%). This strategy provides an approach to design advanced materials for NO 3 − RR.