Computational Screening of N-Doped Graphene-Supported Cu-Sc Nanoclusters for CO2 Capture

Converting carbon dioxide (CO2) into value-added chemicals and/or capturing it before emission are complementary strategies to mitigate rising atmospheric CO2 levels. Copper-based materials are widely investigated for CO2 conversion because Cu can bind and electronically activate CO2 and related intermediates. In this computational research, an evaluation of CO2 activation in CuxScγ nanoclusters (Cu3Sc, Cu2Sc2, and CuSc3) anchored on a graphene bilayer doped with three nitrogen atoms (graphene-3N) was performed using conformational screening and thermochemical adsorption analysis at 298.15, 300, and 400 K. Initially, the Cu3Sc, Cu2Sc2, and CuSc3 nanoclusters were optimized and characterized (relative energy, multiplicity, and electronic characteristics), and the support model (graphene-3N bilayer) was validated by comparing free geometry with partially restricted geometry, corroborating minima through vibrational analysis. Subsequently, CO2 adsorption/activation on CuxScγ @graphene-3N was evaluated, and ΔH and ΔG values were calculated. Ultimately, based on the ΔG(T) values, the Sabatier regimes were established, where it was observed that Cu3Sc exhibits moderate exergonic adsorption (ΔG = −76.07, −67.31, and −58.92 kJ·mol−1 at 298.15, 350, and 400 K). In contrast, Cu2Sc2 exhibits intense adsorption (−165.02, −156.36, and −148.04 kJ·mol−1), and CuSc3 results in practically irreversible fixation (−293.98, −287.32, and −279.09 kJ·mol−1), giving priority to Cu3Sc as the most optimal cluster in terms of activation-regeneration.