Cobalt–aluminum oxide clusters-embedded γ-Al2O3 nanosheets for peroxymonosulfate activation: Interfacial pH-buffering property to eliminate cobalt leaching and boost the catalytic activity

Cobalt–aluminum oxide clusters-embedded γ-Al 2 O 3 nanosheets (CAO@AO) were facilely fabricated and developed for peroxymonosulfate (PMS) activation. Interestingly, the Al–OH-rich amphiphilic surface of CAO@AO endowed the catalyst with unique interfacial pH-buffering property, which stabilized the reaction media at nearly neural level and thus prevented the cobalt sites from leaching. Moreover, the presence of Al–OH groups around the Co−Al oxide clusters facilitated the activation of PMS and the redox cycle of Co 2+ /Co 3+ , which resulted in a boosted catalytic activity. Consequently, the CAO@AO exhibited zero leaching of cobalt and high efficacy for PMS activation, enabling complete and ultrafast removal of metronidazole with a significantly higher turnover frequency (TOF, 1.83 min −1 ) than that of Co 3 O 4 (0.004 min −1 ). It was also demonstrated that introducing suitable foreign metal into CAO@AO could further enhance the catalytic activity (e.g., TOF of Mn(40%)-CAO@AO: 5.80 min −1 ). Furthermore, Mn(40%)-CAO@AO-decorated granular support was synthesized that dominated a continuous-flow degradation in column reaction system.