Revealing the activity origin of oxygen-doped amorphous carbon material for SO2 catalytic oxidation: A descriptor considering dynamic electron transfer during O2 activation

Carbon-based catalytic oxidation widely exists in contamination control, energy conversion and chemical production, in which amorphous carbon containing heteroatom is commonly used carbocatalyst. Compared with crystalline carbon, small-sized aromatic carbon clusters in amorphous carbon exhibit edge and size effect for catalytic oxidation; however, the activity origin, especially accurate activity descriptor remains to be explored. Herein, using SO2 catalytic oxidation as the probe reaction, a combined computational and experimental investigation was conducted to reveal the activity origin of oxygen-doped amorphous carbon. By density functional theory calculations on various oxygen-doped carbon clusters, a site-specific descriptor considering dynamic electron transfer effect was proposed via combining Fukui function and Mulliken electronegativity, based on which the catalytic activity is found to be determined by both oxygen groups and edges. The configuration with cyclic ether embedded into K-region edge is predicted to own the highest activity with O2 activation and SO2 oxidation barrier as low as 35.4 and 89.3 kJ mol−1. SO2 catalytic oxidation dynamic experiments using model amorphous carbocatalysts further validate the favorable role of ether group and edges. This work demonstrates quantitative descriptor for O2 activation and catalytic oxidation on amorphous carbocatalyst, providing guidance for designing high-performance carbocatalyst considering size and edge effect.