Enhanced electrochemical nitric oxide reduction to ammonia via boron-doped carbon catalysts and gas diffusion electrodes

• Developed a dilute NO electrolyzer with a gas diffusion electrode to overcome poor NO solubility. • Integrated boron doping in the carbon framework to enhance NO adsorption and suppress hydrogen evolution. • Employed metal-based boron-doped carbon catalysts for improved electrocatalytic performance. • Achieved optimal performance at –0.9 V cell with Faradaic efficiency of 94.6 % and a peak NH₃ yield of 27.6 × 10⁻⁹ mol s⁻¹ cm⁻². The electrochemical nitrogen oxide reduction reaction (NORR) has emerged as a promising strategy for the removal of harmful nitric oxide (NO) and the efficient synthesis of ammonia (NH₃) under ambient conditions. However, the electroreduction of NO has been hindered by its limited solubility in aqueous electrolytes, often necessitating elevated NO concentrations. This study proposes a novel approach that utilizes a dilute NO electrolyzer coupled with a gas diffusion electrode (GDE) in order to address the mass transport limitations associated with NO electroreduction. Furthermore, boron doping was integrated into the carbon substrate of the catalyst to enhance performance. The incorporation of boron into the carbon framework results in the formation of electron-deficient sites, thereby facilitating the adsorption and activation of NO while simultaneously inhibiting the hydrogen evolution reaction. The synthesis of catalysts involved the embedding of three types of metals on a boron-doped carbon framework. Among them, ruthenium-based boron-doped carbon (Ru-BC) catalysts demonstrated remarkable performance in electrochemical evaluations, exhibiting high-current density and reduced-charge transfer resistance. It was determine that the catalyst achieved optimal performance at −0.9 V cell , with a Faradaic efficiency of 94.6 % and a peak NH₃ yield rate of 27.6 × 10⁻⁹ mol s⁻¹ cm⁻².