About this Research Topic
Researchers nowadays are paying a great deal of attention to the photodecomposition of water into H2 and O2 for the development of a green energy. Numerous attempts have been made to develop visible light-driven photocatalysts for the effective utilization of solar light irradiation.
In the past, metal oxide-based materials have drawn great attention in this area. For instance, titanium dioxide (TiO2) photocatalysts are useful in remote areas where electricity is insufficient. However, because of its large band gap for excitation, only ultraviolet (UV) light irradiation can excite TiO2, which limits its application in a living environment. The search for visible light-active photocatalysts for efficient solar energy conversion has thus intensified. To this end, impurity doping, through metal coating and controlled calcination, has successfully modified the substrates of TiO2 to expand its absorption wavelengths to the visible light spectrum. These modified TiO2 photocatalysts display significantly improved ability in response to visible light illumination.
Visible light responsive-photocatalysts are more convenient than traditional UV light-responsive photocatalysts because they do not require harmful UV light irradiation to function. In addition, water splitting is recognized as one of the most promising techniques to convert solar energy--a clean and abundant energy resource--into chemical energy in the form of hydrogen. In recent years, increasing concern has been directed to not only the development of new photocatalytic materials, but also to the importance of technologies for producing hydrogen and oxygen separately. Photofuel cells can convert solar energy into electrical energy by decomposing bio-related compounds and livestock waste as fuels. Advances to photocatalysts, enabling these solar energy conversion technologies, have been taking place since the discovery of semiconducting TiO2 materials, and have extended to organic-inorganic hybrid materials, such as metal-organic frameworks and porous coordination polymers.
This Research Topic features recent advances in visible light-responsive photocatalysts, intended to develop novel and efficient solar energy conversion technologies, including water splitting, and photofuel cells. We have reviewed and summarized some of the visible light-responsive photocatalysts developed by various research groups. The different techniques adopted for the development of effective visible light-responsive photocatalysts are examined and explained. This Research Topic highlights the ongoing challenges and opportunities in the field of photocatalytic water splitting. It clearly describes the basic concept behind the development of visible light-responsive photocatalysts, which will be helpful for the investigation of novel visible light-responsive materials for future applications, and will introduce general requirements for finding new visible light-active photocatalysts. Themes to be explored here include, but are not limited to:
• Fundamental aspects of semiconductor physics and the behavior of photoexcited carriers during photocatalytic processes.
• Design concepts for different configurations of efficient visible-light responsive photocatalysts.
• Mechanisms of improved visible-light activity in those photocatalytic materials.
• Recent advances in metal-oxide based visible-light responsive photocatalytic materials.
• Combination strategies, including material doping, the adoption of smart architectures, innovative device configuration design, as well as co-catalyst loading and surface modification for highly efficient and stable photocatalysts.
Keywords: Photocatalyst, Visible light-responsive, Energy production, Water splitting, Photofuel cells
Important Note: All contributions to this Research Topic must be within the scope of the section and journal to which they are submitted, as defined in their mission statements. Frontiers reserves the right to guide an out-of-scope manuscript to a more suitable section or journal at any stage of peer review.