Abstract

NH 3 is a crucial chemical feedstock and a promising carbon-free energy carrier; however, its conventional Haber–Bosch synthesis remains energy-intensive and environmentally unsustainable. The electrochemical nitrate reduction reaction (NO 3 RR) presents a dual benefit by enabling simultaneous NH 3 production and nitrate remediation. This study reports the first synthesis of Cu/Cu 2 O nanoparticles anchored on reduced graphene oxide (Cu/Cu 2 O–rGO) via a rapid continuous-wave CO 2 laser–induced thermal shock strategy within 2 min. This approach concurrently reduces Cu 2+ to Cu/Cu 2 O and GO to rGO without chemical reductants, yielding Cu/Cu 2 O nanostructures strongly integrated with conductive rGO. Among the series, the optimized Cu/Cu 2 O–rGO-2 composite—prepared with an optimal Cu precursor loading of 0.2 mmol— exhibited superior NO 3 RR performance, achieving an NH 3 yield rate of 3.30 mg⸱h −1 ⸱cm −2 and a Faradaic efficiency of 90.24% at −0.4 V vs. RHE. Mechanistic in situ and ex situ spectroscopic analyses revealed that in situ electrochemical transformation of Cu/Cu 2 O–rGO into Cu–rGO occurs under reaction conditions, with metallic Cu serving as the dominant active sites and *NO/*NH 2 species identified as key intermediates in the NO 3 RR pathway leading to NH 3 formation.

Furthermore, density functional theory calculations confirmed that electrochemical transformation into Cu–rGO enhances NO 3 RR activity by lowering energy barriers. Remarkably, integration of Cu/Cu 2 O–rGO into a Zn–nitrate battery enables concurrent electricity and NH 3 production with outstanding durability over 100 h. This study demonstrates CO 2 laser thermal shock as a versatile platform for advanced electrocatalyst synthesis and highlights its promise for sustainable NH 3 production and coupled energy–environmental applications.

Keywords: Laser-induced thermal shock; Cu/Cu 2 O–rGO composite; Spectroscopic and DFT insights; Ammonia–Energy Co-Production; Zinc–nitrate batteries