Unveiling Key Insights into the Strategic Design of Photocatalysts for Highly Selective CO2 Reduction to HCOOH: A Computational Study

Achieving carbon neutrality is a critical goal for addressing environmental issues, climate change, and energy needs. This can be accomplished by reducing atmospheric CO₂ levels through capture and conversion into useful fuels or valuable chemicals. To support this goal, our research group recently developed a well-designed, multifunctional Ni-perylene-g-C₃N₄ photocatalyst that enables the highly selective production of formic acid from the CO₂RR. In this study, we used density functional theory (DFT) calculations to investigate and predict the structural properties of hybrid photocatalysts, specifically, perylene-g-C₃N₄ (PCN) and M²⁺-PCN (M²⁺ = Co²⁺, Ni²⁺, Cu²⁺) nanosheets for CO₂ reduction with high efficiency and product selectivity. Our computational results demonstrate that incorporating metal ions can effectively modulate photon absorption and the electronic structure, enhancing CO₂ adsorption, activation, charge transfer, and intermediate adsorption by adjusting the coplanarity between perylene and g-C₃N₄. Our DFT computational calculations indicate that a controlled reaction pathway involving the sequential addition of two electrons and two protons can achieve the highly selective production of oxygenated formic acid: *CO₂^•– → *COOH/*OC(H)O → *COOH^–/*OC(H)O^– → HCOOH. This research provides a molecular-level understanding of the intermediate structures and mechanisms of the CO₂RR, offering valuable insights for the design of efficient photocatalysts.