technology has been developed, that is, the use of photocatalyst inthe reduction of CO2into renewable hydrocarbons such as methane(CH4), methyl formate, methanol (CH3OH), etc. [3,5,6]. It is worthmentioning that the presence of hydrogen (H2) can significantlyimprove the yield of hydrocarbons [7–10]. This is due to the fact thathydrogenation by H2is more favorable than by H2O in the reductionof CO2. However, adding fossil-H2directly for CO2hydrogena-tion is not a practical way because more CO2would be producedby reforming of fossil fuels. Looking forward with a more practi-cal route, to develop a solar-H2is necessary for providing the H2needed in CO2hydrogenation [11].One of the most promising ideas for solar H2is to apply Z-schemewater splitting driven by IO3−/I−shuttle redox mediator [12],then perform CO2hydrogenation in the photoreactor system. Ourgroup recently reported that a twin photoreactor based on the dualphotocatalytic system, which consists of H2- and O2-generatingphotocatalysts divided by a membrane. The main advantage of Z-scheme is that H2and O2can be separately produced [13]. As shownin Scheme 1, in the right-hand side, proton is reduced to hydrogenby photo-excited electrons and CO2can be hydrogenated to hydro-carbons at the same time, while I−is oxidized to IO3−by holes. In