Activity trend and possible descriptor of LaBO3 (B = Cr, Mn, Fe, Co) perovskite catalysts for electroreduction of nitrate

Abstract

Electroreduction of nitrate (ERN) is an encouraging alternative to biological denitrification and the industrial Haber-Bosch process. The search for highly active and low-cost alternative electrocatalysts has brought perovskites to the forefront for ERN. In order to explore the activity trend and possible activity descriptor, ERN activities of perovskite oxides concerning the eg filling state were explored. Herein, lanthanum-based electrocatalytically active perovskite oxides LaBO3 (B = Cr, Mn, Fe, Co) electrocatalysts with B-site consist of four consecutive transition metals were fabricated by sol–gel method. The morphological, structural and elemental properties were studied by SEM, XRD, XPS and electrochemical measurements. A correlation between the eg filling state of reactive B site atom and ERN activity was discovered for perovskite oxides, whereby higher ERN activity was attained for eg filling approaching 1. This work demonstrated the critical role of B site atom and the possibilities of improving the ERN catalytic activities by manipulating the spin orbitals.