Photocatalytic Reduction of CO2 by TiO2 Modified Materials: Recent Advances and Outlook

Carbon dioxide (CO2) is one of the main causes of global warming. Scientists have found that the photocatalytic conversion of CO2 using visible light can not only reduce CO2 emissions and thus mitigate the rise of CO2 concentration in the atmosphere but also produce high-value compounds and fuels, such as CH4, CO, HCOOH, and CH3OH. TiO2-based modified photocatalytic materials have the advantages of high performance and good chemical stability, so they have broad application potential in the field of CO2 photocatalysis. So far, a lot of research has been done on the way of photocatalytic reaction and the development of materials, but these achievements still have a long way to go for practical engineering applications, and the modification of TiO2 groups may be one of the ways to promote its engineering application ability. For this reason, this paper reviews the modification measures of defect engineering, photosensitization, heterojunctions, and so on, hoping to be helpful in follow-up research work in the fields of improving the performance of devices, improving the utilization of visible light, reducing the carrier recombination rate, and changing the efficiency of photocatalytic reduction. Among various modification methods, defect engineering and photosensitization have been applied, but heterojunction construction is still the most effective way to improve the reduction rate. Therefore, in this review, we mainly focus on the construction of heterojunctions to improve the reduction rate, especially on the progress of charge transfer mechanism of different heterojunctions. By summarizing the current research status, the future development of heterojunctions is reasonably considered and speculated.