Construction of CeCux-BTC/CN S-type heterojunctions and photocatalytic CO2 reduction to CO and CH4

S-type heterojunction photocatalysts (CeCux-BTC/CN) of cerium-copper bimetallic organic framework (CeCux-BTC) and graphitic carbon nitride (g-C3N4) were constructed by a simple solvothermal method using cerium nitrate, copper nitrate, and urea as the raw materials, and 1,3,5-benzene-tricarboxylic acid as the ligand for the photocatalytic CO2 reduction to CO and CH4. The results show that the built-in electric field constructed by Fermi energy level flattening transfers the electrons in an S-type manner, which not only preserves the strong reducing properties of the electrons in the material but also provides the maximum redox capacity and enables the composite samples to obtain higher visible-light trapping capacity and improve the separation efficiency of the carriers while refining the crystal particles. With the addition of only 1 mL of H2O as the proton supply source, CeCu0.05-BTC/CN exhibits the optimal photocatalytic performance. The CO and CH4 yields were 64.44 and 0.5575 μmol g−1, which were 7.56 and 2.42 times higher than those of g-C3N4, respectively, and the catalytic performances were basically stable after cycling tests.