Constructing a Bifunctional Heterointerface Realizes Superior Electroreduction of Nitrate-Enriched Wastewater with Wide Concentrations for Ammonia Production

Abstract

Electrochemical nitrate (NO 3 − ) reduction reaction (NO 3 RR), emerges as an ingenious approach to the alternative Haber−Bosch process for ammonia (NH 3 ) synthesis, while the investigation on high performance catalysts remains difficult in regulating NO 3 − adsorption. Herein, we develop a feasible strategy that can simultaneously modulate the adsorption behavior of NO 3 − and thereby lower the energy barrier for NH 3 formation by constructing Cu/Cu 2 O heterointerface with in situ electrochemical transformation of Cu 2 (OH) 2 CO 3 , realizing over 90% Faradaic efficiency (FE) under concentrations from 50 to 1400 ppm, with superior NH 3 yields (0.936−11.21 mg h −1 mg −1 ). Synchrotron radiation−Fourier transform infrared spectroscopy) and density functional theory calculations decipher that the Cu/Cu 2 O heterointerface can realize the balanced adsorption capability of NO 3 − and facilitate the formation of the *NOH intermediate to largely lower the energy barrier of the rate-determining step. The two-electrode flow cell measurement demonstrates its efficiency and practicability to produce a high purity NH 4 Cl solid and NH 3 solution. This work not only provides a rationale for catalyst design for the NO 3 RR but also indicates the feasibility of converting wastewater NO 3 − into valuable NH 3 products.