Fundamental Aspects of Enhancing Low-Temperature CO2 Splitting to CO on a Double La2NiFeO6 Perovskite

Abstract

This paper addresses the synergistic effect of binary Ni–Fe sites in double La2NiFeO6 perovskite on low-temperature CO2 conversion to CO in the reverse water–gas shift-chemical looping process. Experimental investigations and DFT calculations proved that, for the reduction of perovskite, the Ni-site facilitates the formation of surface oxygen vacancies and the adsorption of hydrogen with agile lattice oxygen mobility. Thus, incorporating Ni can improve the reducibility at low temperature. The Fe-site prevents strong adsorption of the CO2 molecules on the La-site to facilitate its direct dissociation into CO molecules, and thereby CO2 conversion increases with Fe loading. Consequently, La2NiFeO6 can satisfy both high reducibility and CO2 splitting activity by the synergy of binary Ni–Fe sites. It presents an average CO productivity of 2.14 mmol/gcat and a maximum CO production rate of 1.69 mmol/gcat·min at 700 °C, more than 4.7-fold and 10-fold higher than each single LaNiO3 and LaFeO3 perovskites, respectively.