Boosting catalytic activity of SrCoO2.52 perovskite by Mn atom implantation for advanced peroxymonosulfate activation

Abstract

Material-enhanced heterogeneous peroxymonosulfate (PMS) activation for degradation of antibiotic in water has attracted intensive attention. However, one challenge is the electron transfer efficiency from the material to PMS for reactive oxygen species (ROS) production. Considering that the B-sites of perovskite oxides are closely associated with the catalytic performance, partial substitution of the B-sites of perovskite oxides can enhance the redox cycle of metals. Consequently, adjusting the ratio of each element at the B site can introduce oxygen vacancies on the surface of perovskite. Herein, a method was developed in which manganese (Mn) partially substitutes B-sites to modify surface properties of SrCoO_2.52 perovskite oxides, resulting in the enhancement of catalytic activity. In degradation kinetics studies using SrCoMnO_3-δ-0.5/PMS (SrCoMnO_3-δ-0.5 denotes that the molar substitution of Mn at the B site of SrCoO_2.52 perovskite oxide is 0.5) reaction system and sulfamethoxazole (SMX) as the target pollutant, it was found that the reaction rate constant (k_obs) is 0.287 min^-1 which is 2.4 times that of SrCoO_2.52/PMS system. Experimental and theoretical analyses revealed that Mn-O covalent bonding governs the intrinsic catalytic activity of SrCoMnO_3-δ-0.5 perovskite oxides. The Mn sites exhibits stronger adsorption energy with PMS than the Co sites, facilitating the breaking of O-O bond. Simultaneously, oxygen vacancies and surface adsorbed oxygen species have a synergistic effect for PMS adsorption. This work can provide a potential route in developing advanced catalysts based on manipulation of the B-sites of perovskite oxides for PMS activation.

Keywords: Manganese substitution; Oxygen vacancies; PMS activation; Perovskite; Sulfamethoxazole removal.