Atomically dispersed iron enables high-efficiency electrocatalytic conversion of nitrate to dinitrogen on a N-coordinated mesoporous carbon architecture

Abstract

Conversion of nitrate to dinitrogen (N2) is a great challenge in environmental remediation, because it is difficult to control a complete N–N coupling reaction for N2 generation. Herein, we report an atomically dispersed iron coordinated with nitrogen on an ordered mesoporous carbon framework (Meso-Fe–N–C) by a multicomponent co-assembly to improve the selectivity of electrocatalytic denitrification. Impressively, the N2 conversion rate (2176 mg N h−1 g−1 Fe) is 1–3 orders of magnitude higher than that of other iron-based and previously reported materials. Both of N coordination and geometric distortion derived from mesostructure tune the electronic structure of Fe site. This leads to a modest adsorption binding strength with key intermediate to balance the amounts of the surface-bound and solvated nitric oxide (NO). Meanwhile, mesochannels confine solvated NO for dimerization via the Eley-Rideal mechanism to promote N2 formation. The applicability over a wide pH range and long-term stability demonstrates potential practical application.