Indium-doped β-MnO2 catalyst for activation of peroxymonosulfate to generate singlet oxygen with complete selectivity

Singlet oxygen ( 1 O 2 ) has been regarded as an excellent active species for the effective degradation of pollutants. However, generating 1 O 2 with high selectivity still remains a significant challenge. Herein, 1 O 2 generation of 100% selectivity for peroxymonosulfate (PMS) activation was achieved by a strategy of indium-doped β-MnO 2 catalyst, affording a dimethyl phthalate degradation rate of 93% within 180 min. Indium active sites served as the active center of the PMS adsorption, and the redox cycling of indium among different valances promoted PMS activation by breaking S–O bond. Density functional theory calculation results demonstrated that HSO 5- could be easily adsorbed at indium site to generate 1 O 2 via effective electron transfer. The indium active sites and oxygen vacancies jointly regulated the PMS decomposition by a non-radical pathway with simultaneous 1 O 2 generation. This work developed a novel indium-doped β-MnO 2 catalyst for complete selective generation of 1 O 2 for highly efficient degradation of pollutants. • A 5% indium doped β-MnO 2 /PMS system was established to remove DMP. • Indium served as the active site for PMS adsorption and activation. • Nonradical pathway ( 1 O 2 ) was responsible for DMP degradation in the system. • DFT analysis indicated that indium doping promoted the breaking of S–O bond in PMS. • 1 O 2 was produced on both indium site and oxygen vacancy during PMS activation.