Ce-doped CuCoO2 delafossite with switchable PMS activation pathway for tetracycline degradation

Heterogeneous Fenton-like catalytic oxidation has exhibited great potential in eliminating recalcitrant organic pollutants. Nevertheless, a precise modulation of intrinsic catalytic pathways (radical or nonradical) remains challenging. Herein, Ce-doped CuCoO2 hexagonal nanosheets (CCCO-x) were designed via a facile coprecipitation method toward peroxymonosulfate activation. The doped Ce optimized the interaction between CCCO-x and PMS and enhanced the interfacial electron transfer ability, tunning the catalytic pathway from radical role (57.4%) to nonradical role (69.2%). More than 96% of tetracycline (TC) could be degraded after Ce doping, accompanied by a first-order kinetic constant that is 2.5 times higher than that of pristine CuCoO2. Meanwhile, the introduction of Ce(III) not only significantly enlarged the specific surface area of the catalyst, but also effectively enhanced the synergistic effect of Co(III) and Cu(I) sites, which further accelerated the PMS decomposition. Besides, synergy of radical-nonradical mixed pathways (SO4•−, •OH, 1O2, and electron transfer pathway) for TC removal was verified by electron paramagnetic resonance (EPR) spectra, quenching tests, and electrochemical measurements. The degradation intermediates and possible degradation pathway of TC were also proposed. This work provides new insights and routes to modulate catalytic pathway in Fenton-like oxidation, especially broadening the application potential of delafossite-based (ABO2) catalysts in water treatment.