Efficient and selective electrochemical reduction of nitrate to N2 by relay catalytic effects of Fe-Ni bimetallic sites on MOF-derived structure

Selective electrocatalytic conversion of NO 3 – to N 2 is an environmental-friendly strategy to close the anthropogenic nitrogen-based cycle. This work reported a metal-organic framework-derived electrocatalyst with earth-abundant bimetallic sites, showing quantitative (~97.9% conversion) and selective (~99.3%) nitrate-to-N 2 transformation. More importantly, both post-catalysis concentrations of NO 3 – and NO 2 – meet the drinking water limit requirements, set by World Health Organization. The reaction intermediates and mechanistic pathways in electrocatalytic reduction of NO 3 – to N 2 are elucidated by a variety of in-situ experimental studies and DFT calculations. The enhanced and selective electrocatalytic performances are ascribed to the relay catalytic effects of the neighboring Fe-Ni catalytic sites residing in the porous carbon electrocatalysts, which are structurally determined by X-ray absorption spectroscopy (XAS) as well as calculated structural model, with Fe sites decreasing the reaction barrier for NO 3 – conversion and Ni centers facilitating the adsorption and activation of reaction intermediates (NO 2 – , NO* and N 2 O*).