| Summary: | In order to improve the catalytic activity of cobalt molybdate (CoMoO<sub>4</sub>), a PDS-activated and UV-vis assisted system was constructed. CoMoO<sub>4</sub> was prepared by coprecipitation and calcination, and characterized by XRD, FTIR, Raman, SEM, TEM, XPS, TGA Zeta potential, BET, and UV-Vis DRS. The results showed that the morphology of the CoMoO<sub>4</sub> nanolumps consisted of stacked nanosheets. XRD indicated the monoclinic structures with C2/m (C<sup>3</sup><sub>2h</sub>, #12) space group, which belong to α-CoMoO<sub>4</sub>, and both Co<sup>2+</sup> and Mo<sup>6+</sup> ions occupy distorted octahedral sites. The pH of the isoelectric point (pHIEP) of CMO-8 at pH = 4.88 and the band gap of CoMoO<sub>4</sub> was 1.92 eV. The catalytic activity of CoMoO<sub>4</sub> was evaluated by photo-Fenton degradation of Congo red (CR). The catalytic performance was affected by calcination temperature, catalyst dosage, PDS dosage, and pH. Under the best conditions (0.8 g/L CMO-8, PDS 1 mL), the degradation efficiency of CR was 96.972%. The excellent catalytic activity of CoMoO<sub>4</sub> was attributed to the synergistic effect of photo catalysis and CoMoO<sub>4</sub>-activated PDS degradation. The capture experiments and the ESR showed that superoxide radical (·O<sub>2</sub><sup>−</sup>), singlet oxygen (<sup>1</sup>O<sub>2</sub>), hole (h<sup>+</sup>), sulfate (SO<sub>4</sub><sup>−</sup>·), and hydroxyl (·OH<sup>−</sup>) were the main free radicals leading to the degradation of CR. The results can provide valuable information and support for the design and application of high-efficiency transition metal oxide catalysts.
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