TiO2-based S-scheme photocatalysts for solar energy conversion and environmental remediation

Solar-driven semiconductor photocatalysis technology is deemed to be a potential strategy to alleviate environmental crisis and energy shortage. Thus, the exploration of high-efficiency photocatalysts is the key to promoting the development and practical application of photocatalysis technology. As a typical photocatalyst, TiO2 has gained extensive attention because of its superb stability, environmental-friendliness, and low price. However, the rapid photo-induced carrier recombination, inadequate light absorption, and insufficient reduction capacity are still the major drawbacks that significantly hamper its photocatalytic performance. Fortunately, the above shortcomings can concurrently overcome by constructing TiO2-based step-scheme (S-scheme) heterojunction photocatalysts with other semiconductors, during which the respective advantages can not only achieve significant spatial carrier separation and robust light-harvesting ability but also preserve the strong redox capacities. Herein, this review presents the latest development in improving the photocatalytic performance of TiO2via the S-scheme heterojunction. Specifically, the classification of TiO2-based S-scheme heterojunction photocatalysts has been detailly described, mainly including metal oxides, metal chalcogenides, organic semiconductors, and other semiconductors. Then, we summarize the current research progress of TiO2-based S-scheme heterojunction photocatalysts in photocatalytic H2 evolution, CO2 reduction, H2O2 production, and pollutant degradation. Simultaneously, various characterization strategies for understanding the photo-induced carrier transfer pathway are also reviewed. Finally, we propose several drawbacks and future prospects in the development of TiO2-based S-scheme heterojunction photocatalysts. It presents an insight into constructing high-efficiency TiO2-based S-scheme heterojunction photocatalysts for energy conversion and environmental remediation.