Mechanism Study of CH4 Decomposition on Carbon Black-Loaded Activated Carbon by DFT Calculation

Carbon black-loaded activated carbon (CB-loaded AC) is a cost-effective catalyst for CH 4 decomposition to produce H 2 . CB induces defects on the AC surface, enhancing catalytic activity. Current studies on the role of defects in promoting CH 4 decomposition are primarily experimental, with unclear mechanisms. Hence, exploring the reaction mechanism of defects in CH 4 decomposition is crucial. In this work, the Grand Canonical Monte Carlo (GCMC) and Density Functional Theory (DFT) are used to construct defects (Mono-Vacancy defect, Di-Vacancy defect, and Stone-Wales defect) on the AC surface, determining the catalytic mechanism of defects in CH 4 decomposition. The results show that during the CH 4 decomposition (C─H bond cleavage) phase, defective AC reduces the energy barriers for CH 4 decomposition. Under identical conditions, the rate-determining step of C─H bond cleavage in CH 4 occurs more readily on AC with Mono-Vacancy, Di-Vacancy, and Stone-Wales defects, with corresponding reductions in energy barriers of 4.64, 2.36, and 3.12%, respectively. The total energy barriers for the reaction are reduced by 12.95, 27.58, and 8.43%, respectively. This indicates that the defects significantly lower the energy barrier for CH 4 decomposition, thereby facilitating the reaction and confirming that these defects act as active sites for the catalytic decomposition of CH 4 on AC.