Infrared-driven high-entropy perovskites for efficient nitrate-to-ammonia conversion via B-site engineering

Abstract

High-entropy perovskite oxides (HEPOs), incorporating five or more principal cations at the A- and/or B-sites of the ABO<inf>3</inf> structure, synergistically combine the configurational entropy and compositional tunability of high-entropy oxides with the structural versatility of perovskites, enabling enhanced atomic-level control over cation distribution, defect chemistry, and multifunctional properties. However, the controlled synthesis of structurally stable HEPOs remains challenging. Herein, we report for the first time a rapid and innovative approach using continuous-wave CO<inf>2</inf> laser irradiation to stabilize high-entropy La(FeCoMnNi)O<inf>3</inf> perovskites via B-site cation engineering with LaFeO<inf>3</inf>. The CO<inf>2</inf> laser, emitting 10.6-μm infrared radiation, is strongly absorbed by a metal–citrate 3D polymeric gel precursor, enabling localized heating and complete HEPO phase formation within 10 min while minimizing thermal diffusion and energy consumption. La(FeCoMnNi)O<inf>3</inf> demonstrates outstanding electrochemical nitrate reduction (eNO<inf>3</inf>RR) performance for high-value ammonia (NH<inf>3</inf>) production, attaining an NH<inf>3</inf> yield rate of 20.29 mg h−1 cm−2 at −0.7 V vs. RHE, with excellent cycling stability. Experimental and theoretical analyses reveal that B-site engineering induces B–O–B bond angle distortion, octahedral tilting, and d -band modulation within the perovskite lattice, enhancing electrical conductivity and NO<inf>3</inf>− activation. Practical NH<inf>3</inf> production via eNO<inf>3</inf>RR was validated via Ar stripping‒acid trapping methods, and La(FeCoMnNi)O<inf>3</inf> was further employed as a cathode in a Zn–NO<inf>3</inf>− battery, demonstrating its multifunctionality. This study establishes CO<inf>2</inf> laser processing as a promising strategy for the rational design of high-entropy perovskite catalysts through precise cation tuning, which is expected to advance environmental and energy applications. © 2025 Elsevier Ltd.