Multifunctional High-Entropy Alloys and Oxides for Self-Powered Electrocatalytic Nitrate Reduction to Ammonia

Graphical High-entropy alloys (HEAs) and high-entropy alloy oxides (HEOs) are considered as promising ORR and NO 3 − RR candidates. By FeNiCoMnRh/NC assembled ZAB coupled to drive NO 3 − RR system (FeNiCoMnCuO x /NC as a cathode), which provides an attractive route for low-energy sewage treatment and environmentally friendly preparation of ammonia. High-entropy alloys (HEAs) show high activities toward oxygen reduction reaction (ORR), Zn-air batteries (ZABs) and nitrate reduction reaction (NO 3 − RR). In this work, FeNiCoMnRh HEA supported by N-doped carbon frameworks is prepared and showed excellent ORR performance with a half-wave potential ( E 1/2 ) of 0.89 V versus RHE, limiting diffusion current ( j L ) of 5.6 mA cm −2 and better current stability. The HEA-assembled ZAB exhibited a high-power density of 103.8 mW cm −2 with a specific capacity of 790 mAh g Zn −1 . Also, its oxides presented 77% Faraday efficiency (FE) for ammonia production at −0.3 V versus RHE. Accordingly, our designed ZAB was employed to drive NO 3 − RR to construct a self-powered system, which provides an attractive route for low-energy sewage treatment and environmentally friendly preparation of ammonia.