Unveiling the ElectrocatalyticActivity of Metallophthalocyanine-BasedCovalent Organic Frameworks Toward CO₂ Reduction Reaction

The electrochemical conversion of carbon dioxide (CO₂) into chemicals or fuels is a promising strategy to enhance carbon capture and reduce greenhouse gas emissions. However, finding highly active electrocatalysts that can selectively generate the desired products is a major obstacle to the process. The present investigation uses density functional theory (DFT) calculations to explore the electrochemical reduction of CO₂ to C₁ products using CoPc-DNDS-COF (DNDS) and CoPc-DSDS-COF (DSDS) frameworks, which contain thiomorpholine and dithiine linkages, respectively. Initially, the structural and electronic properties of the 3D COFs were analyzed by using the periodic hybrid DFT method. Both DNDS and DSDS exhibit small electronic band gaps (<i>E</i>_g) of approximately 0.35 and 0.44 eV, respectively, with significant electronic density of states (DOS) at the Fermi level (<i>E</i>_F), confirmed by the band structure and total DOS calculations. To explore the reaction mechanism, we computationally designed the 2D monolayer slab structure of both of the COFs and studied their structural and electronic properties. The analysis of the 2D monolayer structures revealed DNDS as an indirect band gap semiconductor (1.49 eV), while DSDS showed a slightly higher band gap (1.64 eV). The analysis of the electrocatalytic activity indicates that DNDS efficiently reduces CO₂ to CH₄ with Δ<i>G</i> value of −0.97 eV, whereas DSDS favors CO desorption with Δ<i>G</i> value of 0.68 eV. The present investigations show the efficient electrocatalysis of metallophthalocyanine (MPc) engineered with sulfur-containing linkages toward CO₂RR.