Surface defect-regulated PdCu/TiO2−x promoting efficient electrocatalytic nitrogen reduction

Abstract

Due to the utilization of renewable energy and proton sources, the electrochemical nitrogen reduction reaction is considered as an efficient, sustainable, and carbon-neutral route to replace the industrial Haber–Bosch process. However, restricted by the highly competitive hydrogen evolution reaction and the highly inert NN bond, electrochemical nitrogen reduction research still faces significant challenges with a low level of selectivity and activity. Herein, we demonstrate a catalyst (PdCu/TiO_2−x) composed of oxygen vacancy-rich TiO_2−x nanosheets and PdCu alloy nanoparticles by the co-reduction method of metal precursors. Such a catalyst exhibits excellent electrocatalytic performance at room temperature and pressure, with an NH₃ yield rate of 8.51 mmol g_cat⁻¹ h⁻¹ and the corresponding faradaic efficiency of 49.09% at −0.1 V vs. the reversible hydrogen electrode, which are much higher than most reported palladium-based catalysts and their alloy catalysts. Characterization and experimental results confirm that by properly constructing the surface defect and nanoalloy structure, the optimized electronic structure and synergistic effect can not only effectively improve the N₂ adsorption and activation, but also reduce the reaction barrier, resulting in efficient electrocatalytic performance. Meanwhile, the introduction of Cu accelerates the hydrogen desorption, further effectively improving the faradaic efficiency. Overall, we explored the electrocatalytic performance and mechanism of the bimetal alloy catalyst, as well as the optimization strategies for enhancing the nitrogen mass transfer process, providing new insight into the rational design of a highly efficient e-NRR system through tuning of the catalyst and reaction environment.