The Co d-band center modulation of LaCoO3−δ for improved peroxymonosulfate activation

Abstract

Perovskite-based catalysts for the activation of peroxymonosulfate (PMS) towards organic degradation have attracted significant attention. However, non-metallic element-doped perovskites in the PMS-based advanced oxidation process (AOP) have rarely been reported. Moreover, the intrinsic activity descriptor of perovskites in PMS activation is still controversial. Herein, phosphorus (P) was doped in the B-site of LaCoO_3−δ (LCO) to modulate the structures and catalytic activity in PMS activation. After P doping, we obtained larger lattice spacing, smaller crystal grains, a lower average valence state of Co, more surface oxygen vacancies on the surface, and higher specific surface areas. Moreover, the acidity and redox ability of LaCo_0.8P_0.2O_3−δ (LC_0.8P_0.2O) are improved compared with those of LCO. The electron-occupied orbitals move towards the Fermi level, facilitating electron transfer. The Co d-band center of P-doped LCO is upshifted relative to that of LCO, which favors the interaction between catalysts and PMS. The catalytic activity is enhanced with the increased P doping, and LC_0.8P_0.2O presents an excellent performance over a wide pH range. The mechanism investigation reveals that SO₄˙⁻, ˙OH, O₂˙⁻, and ¹O₂ contribute to the degradation. These findings advance the understanding of the intrinsic activity descriptor of perovskites in AOP and provide insight into the modulation strategy of catalysts to improve the catalytic performance.