Unraveling B, N Co-doping synergy in graphitic carbon nitride for efficient CO2 cycloaddition with styrene oxide

Abstract

The cycloaddition of CO₂ and styrene oxide to produce styrene carbonate under solvent-free conditions offers an eco-friendly, atom-efficient, and highly effective approach to CO₂ utilization. This study presents a highly active and selective catalytic system based on boron and nitrogen co-doped graphitic carbon nitride (BN-GCN) for the efficient production of styrene carbonate. Unlike many conventional catalysts, the BN-GCN system operates without needing solvents or metals, functioning as a metal-free heterogeneous catalyst for the cycloaddition of CO₂ with styrene oxide. It outperforms other heteroatom-doped graphitic carbon nitride (X-GCN) catalysts, with the enhanced activity attributed to the synergistic interaction of reactants with B and N sites. XPS analysis reveals that the N moiety and the B atom are critical active sites for cooperative catalysis. The BN-GCN catalyst achieves 75 % conversion and > 90% selectivity for styrene carbonate (SC) formation under mild conditions (353 K, 2 bar CO₂) within 3 h. Comprehensive material characterization, kinetic studies, and reaction data confirm that B and N co-doping facilitates the co-activation of CO₂ and epoxide. Based on density functional theory (DFT) calculations, and experiments, a convenient mechanism has been proposed for this unique method. The B–N bond duality in BN-GCN offers a cost-effective, sustainable, and efficient catalytic pathway for CO₂ utilization.