Tuning TM–O interaction by acid etching in perovskite catalysts boosting catalytic performance

Abstract

Perovskite oxides have been widely applied as an effective catalyst in heterogeneous catalysis. However, the rational design of active catalysts has been restricted by the lack of understanding of the electronic structure. The correlations between surface properties and bulk electronic structure have been ignored. Herein, a simple handler of LaFeO₃ with diluted HNO₃ was employed to tune the electronic structure and catalytic properties. Experimental analysis and theoretical calculations elucidate that acid etching could raise the Fe valence and enhance Fe–O covalency in the octahedral structure, thereby lessening charge transfer energy. Enhanced Fe–O covalency could lower oxygen vacancy formation energy and enhance oxygen mobility. In-situ DRIFTS results indicated the inherent adsorption capability of Toluene and CO molecules has been greatly improved owing to higher Fe–O covalency. As compared, the catalysts after acid etching exhibited higher catalytic activity, and the T₉₀ had a great reduction of 45 and 58 °C for toluene and CO oxidation, respectively. A deeper understanding of electronic structure in perovskite oxides may inspire the design of high-performance catalysts.