DFT investigation of CO₂ activation and carbon trapping at Ni/Al₂O₃ interfaces in dry reforming of methane

Dry reforming of methane over Ni catalysts offers a route to convert CH 4 and CO 2 into syngas while using two greenhouse gases, but its performance is limited by carbon deposition and poorly understood metal support effects. Here, density functional theory with DFT + U+D2 is used to study a Ni dimer (Ni2) supported on α Al 2 O 3 (0001) and hydroxylated α Al 2 O 3 OH(0001). After validating the structural model against reference data, we examine adsorption of CH 4 , CO 2 , CO, H 2 , and atomic C on bare and Ni-supported surfaces. CH 4 and H 2 show weak, nearly system-independent physisorption, indicating that their activation must occur mainly in the transition states. In contrast, CO 2 and CO are strongly chemisorbed and activated at Ni Al 2 O 3 interfaces, especially on the hydroxylated surface, where large adsorption energies, strong bending, and marked charge transfer are found. Atomic carbon is very strongly stabilized at the same interfacial sites. Analysis of projected density of states, Mulliken charges and electron density differences identifies the Ni alumina perimeter as the key region governing CO 2 activation and coke formation in Ni-based DRM catalysts.