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

Cobalt-aluminum oxide clusters-embedded & gamma;-Al2O3 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 Co2+/Co3+, 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 Co3O4 (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.

Automated summary

Cobalt-aluminum oxide clusters-embedded γ-Al2O3 nanosheets were successfully prepared and utilized for peroxymonosulfate activation. The amphiphilic surface of the catalyst endowed it with unique interfacial pH-buffering property, preventing cobalt leaching. The presence of Al-OH groups facilitated PMS activation and the redox cycle of Co2+/Co3+, leading to enhanced catalytic activity. Introducing suitable foreign metals further improved the catalytic activity, and a granular support decorated with Mn(40%)-CAO@AO was synthesized for continuous-flow degradation.