Theoretical Study of Novel Two-Dimensional Conductive Metal–Organic Frameworks TM3(HAT)2 as Promising Electrocatalysts for CO2 Reduction

It is vital to search for efficient CO₂ reduction reaction (CO₂RR) electrocatalysts for synthesizing value-added targeted products. In this work, by using density functional theory (DFT) calculations, we systematically investigated the electrocatalytic CO₂RR performance of the novel two-dimensional (2D) conductive metal–organic framework (MOF) TM₃(HAT)₂ monolayers (TM = Ti, V, Cr, Mn, Fe, Co, Ni, and Cu; HAT = 1,4,5,8,9,12-hexaazatriphenylene). The CO₂RR catalytic activity of the designed catalysts is highly correlated with the d-electron number of TM active sites. Co₃(HAT)₂ is found to be the most promising CO₂RR catalyst with a calculated limiting potential (U_L) value of −0.23 V for the CH₄ product, followed by Ni₃(HAT)₂ toward both the CH₄ and CH₃OH products (U_L = −0.34 V). Moreover, the thermodynamic and electrochemical stability simulations suggest that the screened-out Co₃(HAT)₂ and Ni₃(HAT)₂ with high activity are also with good stability. Importantly, these two catalysts could inhibit the competitive hydrogen evolution reaction, further demonstrating their high activity and selectivity for the CO₂RR. The results not only contribute to the search for efficient CO₂RR electrocatalysts that are used in high-value fuels but also shed light on the opportunities to explore electrochemical applications based on 2D conductive MOFs.