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

High-entropy alloys (HEAs) show high activities toward oxygen reduction reaction (ORR), Zn-air batteries (ZABs) and nitrate reduction reaction (NO₃ ^-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 NO₃ ^-RR to construct a self-powered system, which provides an attractive route for low-energy sewage treatment and environmentally friendly preparation of ammonia.