Theoretical and experimental investigation into photoelectrocatalytic oxidation and reduction property of ZnFeTi mixed metal oxides

In this paper, we synthesized ZnFeTi layered double hydroxides (LDHs) by hydrothermal synthetic method at high temperature. The LDHs was further calcined by microwave to make ZnFeTi mixed metal oxides (MMO) with special particle size. In addition, the band gap of ZnFeTi-LDHs and MMO were calculated by DFT for the first time, which was in good agreement with the experimental result from UV–vis. MMO was finally dye sensitized and used as thin film electrode to test the photoelectrocatalytic performance for both p -chlorophenol oxidation degradation and CO 2 reduction under visible light. The results showed that without the applied voltage, the p -chlorophenol degradation and CO 2 reduction rates were not high; after the electric filed was introduced into the reaction, not only the degradation efficiency of p -chlorophenol was increased to 99.1% within 210   min, but also the reactivity of CO 2 reduction reaction was enhanced a lot. Furthermore, from the results of HPLC and UV–vis, we could conclude that p -chlorophenol was finally decomposed into small inorganic molecules going through 4-chloropyrocatechol and hydrochinone under the co-effect of hydroxide radicals and the photoelectrons. This result could be proved by frontier electron densities on atoms of p -chlorophenol calculated by DFT.