Photocatalytic reduction of CO2 to CO over the Ti–Highly dispersed HZSM-5 zeolite containing Fe

Iron-containing HZSM-5 zeolite, which was shown as an efficient and stable photocatalyst for photocatalytic CO2 reduction in our previous research, was chosen to prepare a Ti-HZSM-5 hybrid via sol-gel method. The characterizations by XRD, UV–vis DRS, Raman, and XPS demonstrate that Ti species highly dispersed as nanoclusters or mono-sites on the HZSM-5 zeolite surface. Compared with the common TiO2-HZSM-5 composite sample, the as-prepared Ti-HZSM-5 sample exhibits an enhanced activity for photocatalytic CO2 reduction due to higher concentration of excited state electrons and faster electron transfer rate. The Ti-HZSM-5 sample with 0.99 wt% of Ti content is observed to have the highest rate for the photocatalytic CO2 reduction. And the characterization results of photocurrent and ESR reveal that Ti species and Fe species work synergistically upon UV-light irradiation, therefore, we propose a possible reaction mechanism of CO2 photoreduction on Ti-HZSM-5. This work highlights the promising prospect of hybridizing of the Fe-O species in zeolite with semiconductors for enhanced photocatalytic performance.