Abstract

The electrochemical synthesis of ammonia (NH 3 ) via the nitrate reduction reaction (eNO 3 RR) intends an efficient replacement to the Haber–Bosch technique, operating under ambient conditions. Nitrate-based voltaic cells present a trifecta solution by simultaneously removing wastewater pollutants, producing NH 3 , and generating energy. Herein, high-entropy spinel oxide (HE-SPO) derived from divalent (Mn, Fe, Co, Ni, and Cu) 3d transition metals were transformed into single-phase (MnFeCoNiCu)O high-entropy rock-salt oxides (HE-RSO) via pulsed laser irradiation in liquids, achieving high-entropy phase twisting with structural stabilization. The HERSO electrocatalyst demonstrated exceptional eNO 3 RR-to-NH 3 conversion, with an NH 3 production rate of 15.34 mg h −1 cm −2 at −0.4 V vs. RHE and a Faradaic efficiency of 92%. In situ Raman spectroscopy revealed Co and Cu as dual-active sites, facilitating the N-end mechanism for eNO 3 RR, which was further validated via density functional theory calculations. Leveraging this high-efficiency eNO 3 RR-to-NH 3 system, the HE-RSO catalyst was integrated into a Zn– nitrate battery, reaching a high output voltage of 1.22 V and a power density of 1.75 mW cm −2 .

This study highlights the pulsed laser process as a new avenue for high-entropy structural stabilization and underscores the potential of HE-RSO for sustainable NH 3 production and integrated energy applications.