Affiliation:
1. Department of Chemistry (BK21 FOUR) Research Institute of Advanced Chemistry Gyeongsang National University Jinju 52828 Republic of Korea
2. Beamline Division Synchrotron Light Research Institute (SLRI) Nakhon Ratchasima 30000 Thailand
3. Nano‐Technology Research Laboratory, Department of Chemistry GLA University Mathura Uttar Pradesh 281406 India
4. Core‐Facility Center for Photochemistry & Nanomaterials Gyeongsang National University Jinju 52828 Republic of Korea
Abstract
AbstractThe electrochemical synthesis of ammonia (NH3) via the nitrate reduction reaction (eNO3RR) intends an efficient replacement to the Haber–Bosch technique, operating under ambient conditions. Nitrate‐based voltaic cells present a multifunctional system by simultaneously removing wastewater pollutants, producing NH3, and generating energy. Herein, high‐entropy spinel oxide (HE‐SPO) derived from divalent (Mn, Fe, Co, Ni, and Cu) 3d transition metals are 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 HE‐RSO electrocatalyst demonstrated exceptional eNO3RR‐to‐NH3 conversion, with an NH3 production rate of 15.34 mg h−1 cm−2 at −0.4 V versus 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 eNO3RR, which is further validated via density functional theory calculations. Leveraging this high‐efficiency eNO3RR‐to‐NH3 system, the HE‐RSO catalyst is 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 NH3 production and integrated energy applications.
Funder
Gyeongsang National University
National Research Foundation of Korea
Korea Basic Science Institute