Strengthening nitrogen affinity on CuAu@Cu core-shell nanoparticles with ultrathin Cu skin via strain engineering and ligand effect for boosting nitrogen reduction reaction

摘要

Although the electrochemical nitrogen reduction reaction (NRR) is regarded as a promising alternative to the Haber-Bosch process, it still suffers from the poor activity and low selectivity. Herein, we propose a powerful strategy to simultaneously boost the activity and selectivity by introducing strain engineering into the design of NRR electrocatalysts. The strain-engineered electrocatalysts consisted of monodisperse CuAu@Cu core-shell nanoparticles with controllable Cu skin via one-pot solvothermal process. Among them, electrocatalysts with about 2 layers of atomic Cu skin (CuAu@2LCS) achieve the highest NH3 yield rate (33.9 mu g(NH3) h(-1) mg(cat.)(-1)) and Faradic efficiency (24.1 %) at -0.2 V vs. RHE in 0.1 M HCl. Density functional theory (DFT) calculations reveal that owing to the unique structure of bimetallic alloys with the ultra-thin Cu skins, tensile strain and favorable ligand effect work together and tune the surface electronic structure of electrocatalysts, which not only strengthen N-2 affinity but also suppress the competitive HER process.