Theoretical Study on Selective Adsorption, Synergistic Effects, and Conversion of NO2 and SO2 on Cug/PCN Contribute to the 'Innovations in Catalysis with Earth Abundant Metals' collection in Catalysis Science & Technology

Abstract

This study employs density functional theory calculations to investigate the adsorption and conversion mechanisms of typical flue gas components (NO, NO2, SO2) on geminal-copper pair anchored polymeric carbon nitride (Cug/PCN). The results show that Cug/PCN exhibits significantly stronger adsorption of NO and NO2 than SO2. This high selectivity is primarily due to strong chemical bonding and substantial charge transfer between the Cu sites and NO/NO2 species. A key finding is the quantitative confirmation of a significant attractive interaction (-ICOHP = 0.96 eV) between two co-adsorbed NO molecules, obtained via Crystal Orbital Hamiltonian Population (COHP) analysis. This reveals a multi-molecular cooperative adsorption mechanism, which explains the exceptionally high adsorption strength of NO compared to predictions from single-molecule models. Furthermore, it provides a pre-activated configuration that facilitates subsequent efficient conversion of NO, such as the dimerization 2NO → N2O. Free energy calculations confirm that this conversion pathway is thermodynamically highly favorable. This research provides a theoretical basis for designing flue gas purification materials that integrate sensing and catalytic functions, and underscores the critical role of cooperative adsorption in complex multi-molecular environments.