Ti3C2-based MXene anchoring single-atom Co as a long-lasting peroxymonosulfate activator enabling efficient water decontamination: Deciphering the critical role of titanium vacancies

Cobalt atoms anchored on Ti3C2-based MXene (i.e., Co-SA/MXene) have been successfully endowed with exceptional catalytic performance for the elimination of aqueous micropollutants. Herein, we firstly proposed a coupling method of etching-exfoliation-reduction to enrich titanium vacancies. The as-synthesized Co-SA/MXene exhibited a superior removal efficiency of ranitidine of 100 %, and the corresponding reaction kinetics constant (μmol/s•g) was 1.11–6643.53 times higher than the state-of-the-art for ranitidine degradation. The introduction of abundant titanium vacancies enabled a long-lasting life via an accelerated valence cycling of Co(II) and Co(III), and also effectively inhibited toxic Co2 + leaching. DFT revealed that OII/OIII dual-atoms were more suitable for PMS adsorbing while offering stronger adsorption energy, and further offered a new insight into the PMS activation mechanism for 1O2 selected generation. This work revealed that oxidation behavior of ranitidine and established an attractive water treatment technique for the rapid removal of aqueous micropollutants. [Display omitted] •Co-SA/MXene exhibited a long-lasting reactivity for micro-pollutants rapid degradation.•The introduction of abundant titanium vacancies effectively inhibited the leaching of toxic Co2+.•A new perspective for the oxidation behavior and eco-toxicity change of ranitidine was proposed.•DFT calculations coupled with experiments demonstrated the mechanism of PMS activation.