Constructing Pillar-Layered Covalent Organic Frameworks via Metal-Ligand Coordination for Electrochemical CO₂...

Growing global concerns over energy security and climate change have intensified efforts to develop sustainable strategies for electrochemical CO₂ reduction (eCO₂RR). Covalent Organic Frameworks (COFs) have emerged as promising electrocatalysts for eCO₂RR due to their tunable structures, high surface areas, and abundance of active sites. However, the performance of 2D COFs is often limited by layer stacking, which restricts active site exposure and reduces selectivity. To overcome these challenges, a new class of COFs known as pillar-layered COFs (PL-COFs) is developed featuring adjustable interlayer spacing and a 3D architecture. Characterization using PXRD, TEM, XPS, and EIS confirmed the successful integration of pillar molecules, which leads to increased interlayer spacing, crystallinity, and porosity. These structural advancements result in significantly improved electrochemical activity and selectivity for CO₂-to-CO conversion. Density functional theory simulations revealed that enhanced CO₂ adsorption and CO desorption contribute to the outstanding performance of PL-COF-1, which boasts the largest interlayer spacing. This material achieved an impressive Faradaic efficiency of 91.3% and demonstrated a significant current density, outperforming both the original COF-366-Co and PL-COF-2. These findings highlight the effectiveness of the pillaring strategy in optimizing COF-based electrocatalysts, paving the way for next-generation materials for CO₂ reduction and sustainable energy conversion.