Surface hydroxyl-mediated modulation of γ-Al2O3 to enhance Ni-catalyzed CO2 methanation at low temperatures

Reaching high activity over Ni-based catalysts for CO 2 methanation at lower temperature remains a critical challenge. Herein, a surface hydroxylation strategy was developed to enhance the catalytic performance of Ni catalysts under mild conditions. By treating γ-Al 2 O 3 with H 2 O 2 solutions of varying concentrations, the surface hydroxyl (–OH) group density was effectively tuned. Catalytic evaluations revealed that hydroxylation of the support significantly enhances CO 2 methanation performance. Among the series, Ni/A-OH-6 exhibited the highest activity, achieving a turnover frequency (TOF) of 2.129 h −1 at 240 °C, approximately eight times higher than that of the unmodified Ni/A catalyst (0.266 h −1 ), thereby demonstrating a remarkable enhancement in intrinsic activity. Comprehensive characterizations demonstrated that surface –OH significantly enhanced CO 2 adsorption via the formation of HCO 3 * species. In situ DRIFTS studies further confirmed that hydroxyl-induced HCO 3 * species convert more readily to HCOO*, facilitating the hydrogenation pathway and thus contributing to the improved low-temperature activity. This work highlights surface hydroxyl engineering as a simple yet effective approach to boost catalytic efficiency, delivering guidance for the rational development of high-efficiency CO 2 utilization catalysts.