Abstract
This study investigates methane decomposition on NiFe2O4 and CaO-Ni3Fe catalysts via DFT and microdynamic modeling. The NiFe2O4 surface exhibits only weak physical adsorption of CH4, with a high activation energy of 1.87 eV for the first dehydrogenation step. Deep dehydrogenation to form CO requires overcoming an even higher activation barrier of 2.79 eV. In contrast, the CaO-Ni3Fe interface significantly reduces the activation energy for the first CH4 dehydrogenation step. Notably, a dual-path competition emerges at this interface: a carbon deposition pathway (CH3∗ → C∗) and a CO formation pathway (CH3∗→ CO). CaO promotes the oxidation of deposited carbon (C∗ + O → CO∗) via active oxygen species, combined with interfacial electron modulation. Furthermore, CaO reduces the apparent activation energy for the CO formation pathway to 4.51 eV, thereby optimizing the selectivity towards CO generation. Regarding the dual-path reaction scenario, low-temperature reactivity is governed by carbon oxidation control, while the reaction shifts towards the conversion of the CH3∗ intermediate at elevated temperatures. This study elucidates the temperature-dependent mechanism of dual-path competition, providing a theoretical foundation for designing carbon-resistant methane reforming catalysts.