Insights into atomic arrangement in CuMnO2 with tailored exposed crystal facets for effectively micropollutant oxidation via peroxymonosulfate activation

Crystal facet engineering of bimetallic ABO2 oxides is regarded as decisive strategy for regulation of catalytic activity, whereas precisely identifying the intrinsic mechanism of facet-dependent activity are still significant challenging. Herein, crednerite CuMnO2 nanoflake material with tailored crystal facets were synthesized and identified as efficient peroxymonosulfate (PMS) activators, in which CuMnO2-160 catalyst with exposed (201) facet exhibited more superior catalytic efficiency compared to CuMnO2-80 with (020) facet towards 4-hydroxybenzoic acid oxidation. Notably, CuMnO2-160 demonstrated substantial activity across a wide pH range even under high concentration inorganic anions and humic acid (HA). Quenching experiments and EPR spectra elucidated the crucial reactive species of •OH and SO4•-, with 1O2 playing an auxiliary role in p-hyhydroxybenzoic acid (HBA) degradation. Computational analysis and characterization results collectively revealed that PMS molecules adopted two distinct adsorption modes on different CuMnO2 facets, and the PMS adsorption-activation behavior was significantly altered by detailed atom arrangement of CuMnO2 in tailored exposed facets, thereby lowering the charge transfer energy barrier to favor PMS bonding interaction on (201) facet. This study systematically underscores the catalyst microstructure and crystal facet dominated PMS activation behavior and oxidation mechanism, providing valuable and novel insights for further understanding of crystal facets and the morphology control relied catalytic mechanism.