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

Abstract Carbon black‐loaded activated carbon (CB‐loaded AC) is a cost‐effective catalyst for CH₄ decomposition to produce H₂. CB induces defects on the AC surface, enhancing catalytic activity. Current studies on the role of defects in promoting CH₄ decomposition are primarily experimental, with unclear mechanisms. Hence, exploring the reaction mechanism of defects in CH₄ 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 CH₄ decomposition. The results show that during the CH₄ decomposition (C─H bond cleavage) phase, defective AC reduces the energy barriers for CH₄ decomposition. Under identical conditions, the rate‐determining step of C─H bond cleavage in CH₄ 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 CH₄ decomposition, thereby facilitating the reaction and confirming that these defects act as active sites for the catalytic decomposition of CH₄ on AC.