Synthesis of a UiO-66/g-C 3 N 4 composite using terephthalic acid obtained from waste plastic for the photocatalytic degradation of the chemical warfare agent simulant, methyl paraoxon.

In our study, Zr-based UiO-66 (Zr) was synthesized using terephthalic acid obtained from waste plastic. Thereafter, UiO-66/g-C 3 N 4 composites were prepared by the solvothermal method, and their photocatalytic activity in the photodegradation of the chemical warfare agent simulant, dimethyl 4-nitrophenyl phosphate (DMNP), was evaluated. The as-synthesized UiO-66/g-C 3 N 4 exhibited a high surface area (1440 m 2 g -1 ) and a high capillary volume (1.49 cm 3 g -1 ). The UiO-66/g-C 3 N 4 samples absorbed a visible light band with bandgap energies of 2.13-2.88 eV. The as-synthesized UiO-66/g-C 3 N 4 composites exhibited highly efficient degradation of DMNP with a short half-life ( t 1/2 of 2.17 min) at pH 7 under visible light irradiation. The trapping experiments confirmed that the h + and ˙O 2 - radicals played an important role in the photocatalytic degradation of DMNP. The UiO-66/g-C 3 N 4 catalyst simultaneously performed two processes: the hydrolysis and photocatalytic oxidation of DMNP in water. During irradiation, a p-n heterojunction between UiO-66 and g-C 3 N 4 restricted the recombination of photogenerated electrons and holes, resulting in the enhancement in the degradation rate of DMNP.