Laser-induced Mo valence engineering in Cu2O enables efficient nitrate electroreduction

Abstract

Electrolytic nitrate reduction to ammonia (NO₃⁻RR) offers a promising alternative to the energy-intensive Haber-Bosch process, providing a lower-energy pathway for sustainable ammonia production. Here, we report a laser-assisted strategy to modulate the valence states of molybdenum in Mo-doped Cu₂O (LG-Mo-Cu₂O/CF). The catalyst, synthesized via hydrothermal doping followed by laser treatment, enables Mo⁶⁺ reduction of to Mo⁴⁺. The low-valent Mo species promote H₂O dissociation to generate surface-bound hydrogen (*H), thereby facilitating the hydrogenation steps of NO₃⁻RR. At a NO₃⁻ concentration of 0.1 M, the LG-Mo-Cu₂O/CF catalyst delivers excellent performance, achieving an NH₃ yield of 10.9 mg h⁻¹ cm⁻² and a Faraday efficiency of 94.3 % at −0.5 V vs. RHE, along with a nitrate-to-ammonia conversion rate of 93.2 %. This work highlights the potential of laser-enabled valence engineering as an effective approach to enhance the activity and selectivity of NO₃⁻RR electrocatalysts.