High-ammonia selective metal-organic framework-derived Co-doped Fe/Fe2O3 catalysts for electrochemical nitrate reduction

Ammonia (NH3) is an ideal carbon-free power source in the future sustainable hydrogen economy for growing energy demand. The electrochemical nitrate reduction reaction (NO3-RR) is a promising approach for nitrate removal and NH3 production at ambient conditions, but efficient electrocatalysts are lacking. Here, we present a metal-organic framework (MOF)-derived cobalt-doped Fe@Fe2O3 (Co-Fe@Fe2O3) NO3-1RR 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, NH3 was produced at a rate of 1,505.9 mu g 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@Fe2O3 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.

Automated summary

Metal-organic framework-derived cobalt-doped Fe@Fe2O3 catalyst shows high efficiency in electrochemical nitrate reduction and ammonia production, providing an important strategy in the design of electrocatalysts.