Hollow mesoporous carbon supported Co-modified Cu/CuO electrocatalyst for nitrate reduction reaction.

The electroreduction of nitrate (NO) pollutants to ammonia (NH) provides a sustainable approach for both wastewater treatment and NH synthesis. However, electroreduction of nitrate requires multi-step electron and proton transfer, resulting in a sluggish reaction rate. Herein, we synthesized a Co-modified Cu/CuO catalyst supported on hollow mesoporous carbon substrates (Co/Cu/CuO-MesoC) by a one-step microwave-assisted reduction method. At -0.25 V vs. reversible hydrogen electrode (RHE), Co/Cu/CuO-MesoC shows a Faradaic efficiency (FE) of 100 ± 1% in 0.1 M NO. Notably, the maximum NH yield rate (Yield) reaches 6.416 ± 0.78 mmol mgh at -0.45 V vs. RHE, which is much better than most of the previous reports. Electrochemical evaluation and in-situ Fourier transform infrared (FTIR) spectroscopy reveal that the addition of Co could promote water electrolysis, and the generated H* is involved in the following hydrogenation of intermediates, ultimately leading to faster kinetics and energetics during electrocatalytic conversion of NO to NH. This synergetic electrocatalysis strategy opens a new avenue for the development of high-activity, selectivity, and stability catalysts.