Facet exposed-dependent surface bonding patterns between CuO and peroxymonosulfate vary activation mechanism: Reactive species and degradation pathways

The elusive factors determining peroxymonosulfate (PMS) activation lead to the “trial-and-error” method when developing efficient catalysts. Herein, we demonstrate that the suitable bonding pattern between PMS and exposed facets of CuO is the key parameter in catalysis. The kobs of ibuprofen removal by CuO with (110) facet (p-CuO) was 1.67 times higher than that of CuO with (001) facet (c-CuO). Simultaneously, Cu(III) was confirmed to be the primary intermediate oxidant among multiple reactive species (Cu(III), •OH, and 1O2 in both CuO/PMS systems, whereas O2•− only in c-CuO/PMS system). Furthermore, density functional theory calculations unveiled that compared to chaise longue connection between p-CuO and PMS, the higher adsorption energy (Eads) of bridge-like connection between c-CuO and PMS leads to a more stable intermediate (−5.56 eV vs −3.76 eV), thus hindering the formation of Cu(III). This work provides new opportunities for fabricating diverse metal oxides with new interfaces as PMS catalysts.