Doping Pd2+ into NinCeOx nanofibers promotes low-temperature CO2 methanation

CO 2 methanation at low temperatures is still a challenge. Herein, Ni n CeO x (n = 1–3) and Ni 2.5 Pd 0.1 CeO x nanofibers by electrospinning is reported. The main advantage of this method is to obtain the highly dispersed precursor of palladium, nickel, and cerium, overcoming the difficulty of uniform mixing in conventional preparation methods. The Ni 2.5 Pd 0.1 CeO x nanofiber catalyst exhibited outstanding catalytic performance at low temperatures (CO 2 conversion rate = 90.4 %, CH 4 selectivity = 99.6 % at 230 °C) along with exceptional stability over 300 h. EPR, Raman, and O 1s XPS confirmed that Pd 2+ doping increased oxygen vacancy concentration. In-situ infrared spectroscopy indicated that CO 2 methanation on Ni 2.5 CeO x and Ni 2.5 Pd 0.1 CeO x catalysts followed the formate pathways. Pd 2+ doping increased the number of surface oxygen vacancies and hydroxyl groups, thus increasing the amount of bicarbonates and formates. DFT calculations suggested that Pd 2+ doping increased CO 2 adsorption energy, and confirmed surface hydroxyl groups and bicarbonate being beneficial for CO 2 methanation, consequently enhancing the activity of Ni 2.5 Pd 0.1 CeO x catalyst especially at low temperatures.