Structural reconstruction via ligand competition in CuBDC–Bpy catalysts for selective CO2 electroreduction to CH4

Among the various electrochemical CO 2 reduction reaction (CO 2 RR) products, methane (CH 4 ) is particularly attractive due to its high energy density and compatibility with existing natural gas infrastructure. However, achieving high CH 4 selectivity remains challenging because of sluggish proton-coupled electron transfer kinetics and competing reaction pathways. Herein, we propose a ligand competition strategy to construct catalysts, where bipyridine (Bpy) competitively coordinates with 1,4-benzenedicarboxylic acid (BDC) to generate a mixed-ligand framework, transforming the framework into ordered nanosheet architectures while tuning the Cu valence state. The CH 4 selectivity exhibits a volcano-shaped dependence on BDC/Bpy ratio, with the maximum CH 4 Faradaic efficiency of 56.2% at −2.0 V vs. RHE for BDC/Bpy=2 (CuBDC–Bpy–2). Post-reaction analysis reveals nanosheet collapse after electrolysis, whereas in situ IR detects *OCH 3 species associated with CH 4 formation, indicating that Bpy incorporation modulates hydrogenation pathways, although structural degradation occurs during prolonged operation. This work demonstrates that competitive coordination between BDC and Bpy can serve as a structural design principle for tuning active-site electronic states and reaction pathways.