Laser-induced PdCu alloy catalysts for highly efficient and stable electrocatalytic nitrate reduction to ammonia

The electrochemical reduction reaction of nitrate (NO₃RR) to ammonia is an environmentally friendly approach that can treat wastewater as well as find an alternative to the energy-intensive Haber-Bosch process. The use of adhesives partially to adhere to the NO₃RR electrocatalysts, leading to sluggish kinetics, poor stability and poor scalability. Herein, we report the synthesis of PdCu alloy catalysts via a direct laser writing method, demonstrating their exceptional performance in the electrochemical reduction of nitrate. The Pd_0.55Cu_0.45 alloy exhibited a remarkable ammonia production rate of 30.55 mg h^-1 cm^-2 under neutral electrolyte conditions and maintained stable operation for over 1500 h. Density functional theory (DFT) calculations and experimental analyses revealed that the PdCu alloy's enhanced activity stems from its lower energy barrier for the rate-determining step (*NO → *NOH) and improved mass transfer capabilities. The alloy's electronic properties and geometric configuration, fine-tuned by the laser-induced synthesis method, facilitate the conversion of NO₂^- and suppress the hydrogen evolution reaction (HER), thereby significantly enhancing the selectivity and activity of the NO₃RR process. This study provides a sustainable and efficient pathway for ammonia synthesis and offers insights into the design of advanced catalysts for environmental and energy applications.