Thermal reduction-assisted electronic structure tuning of perovskite oxide as catalyst for efficient advanced oxidation

Development of efficient and green heterogeneous catalyst is a challenging goal in peroxymonosulfate (PMS)-based advanced oxidation processes (AOPs) for wastewater remediation. Perovskite-type oxides with rich physicochemical properties and flexible structure are one of the most promising categories of heterogeneous catalysts to activate PMS, while appropriate structural tuning is key to develop highly active perovskite oxides for efficient wastewater treatment. Here, we propose a simple strategy based on facile high-temperature quenching to significantly improve activity of perovskite oxide LaCoO_3-δ (LCO) for PMS activation. Such quenching process improves bivalent cobalt over the surface of LCO, enhances electron transfer rate, and increases surface oxygen defects, consequently improving the decomposition rate of PMS. Specifically, compared with LCO prepared from naturally cooling at 600 °C (LCO-600-C), directly quenched LCO sample (LCO-600-Q + C) shows more than 50% improvement in catalytic activity for phenol degradation. Sulfate radical and singlet oxygen are identified as the dominating reactive oxygen species (ROS) by in-situ electron paramagnetic resonance spectroscopy and radical scavenging experiments, but a different generating rate of SO₄^·- over LCO-600-Q + C and LCO-600-C. Such a strategy may be suitable for the design and development of other type of materials.