Cerium-cobalt bimetallic metal–organic frameworks with the mixed ligands for photocatalytic degradation of methylene blue

The Ce/Co bimetallic metal–organic frameworks (MOFs) with the mixed ligands of 1,4-benzenedicarboxylic acid (H2bdc) and 1,3,5-benzenetricarboxylic acid (H3btc) were synthesized by a one-step solvothermal method. The photocatalytic activity was investigated under xenon lamp irradiation using methylene blue (MB) as a simulated pollutant. Photocatalytic performance tests showed that DT-3 was the best photocatalyst with the Ce/Co ratio of 4:1, and the H2bdc/H3btc ratio of 1:2. In detail, for DT-3, the photocatalytic degradation efficiency of MB could reach 97.6% in 120 min. Combined with the result of the UV–vis diffuse reflectance spectrum and Mott-Schottky curve, the bandgap energy (Eg)of DT-3 equaled to 3.20 eV; in addition, the conduction band potential (ECB) of DT-3 (– 0.75 eV) was more negative than the standard redox potential of O2/·O2– (– 0.33 eV), while the valence band potential (EVB) of DT-3 (2.45 eV) was higher than the redox potential of MB (1.77 eV). In all, the experimental results showed that the synthesized bimetallic photocatalyst with the mixed ligands could effectively degrade the organic dye MB in wastewater.