A pragmatic perspective article: synergistic photocatalytic-photothermal effect with its practical applications and future prospects

As a feasible strategy to solve worldwide energy problems, solar energy attracts much attention due to its merits of low cost, stability and no space limit. Photocatalysis attracts wide attention since it is considered as one of the promising ways to utilize solar energy. However, the limitations of photocatalysis prohibit its further practical applications. The synergistic photocatalytic-photothermal route can realize more effective utilization of solar light. It can not only overcome restrictions of photocatalysis but also produce required localized heat for reaction from UV-visible light to near infrared light. Thus, photocatalytic-photothermal effects are widely used in various fields. Achieving a high solar-to-heat conversion rate plays an essential role in the fields of hydrogen generation, carbon dioxide reduction, antimicrobial and membrane separation. Especially, sterilization can effectively exhibit its own superiority and inhibit the limitation of photocatalysis. The temperature can increase until reaching the denaturation temperature of bacteria by local heat effect induced by the photothermal effect. In addition, the photocatalytic-photothermal effect in membrane separation could be beneficial by generating more radicals. Meanwhile, temperature induced by photon energy could improve water evaporation and water permeation performance. Our previous studies on antibacterial and wastewater treatment by the photothermal-photocatalytic effect are introduced. We proposed that high photothermal conversion efficiency and efficient generation of photo-induced holes and electrons were beneficial for forming more ROS species. These active species were powerful for oxidizing bacteria leading to their death, completely mineralizing organic pollutants or recovering heavy metals. According to proposed photothermal-photocatalytic mechanisms, new perspectives and insights are provided for the wide utilization of the photocatalytic-photothermal effect in the future. The synergistic photocatalytic-photothermal effect realizes more effective utilization of solar energy, which can be used in the fields of hydrogen generation, carbon dioxide reduction, sterilization and membrane separation.