Photocatalytic Water Splitting Under Visible Light: Concept and Catalysts Development

Abstract

Sustainable hydrogen production is a key target in the development of alternative energy systems of the future for providing a clean and affordable energy supply. The conversion of solar energy into hydrogen via a water-splitting process assisted by photosemiconductor catalysts is one of the most promising technologies for the future because large quantities of hydrogen can potentially be generated in a clean and sustainable manner. Undoubtedly, the conversion of solar energy into a clean fuel (H 2 ) under ambient conditions is the greatest challenge facing scientists in the twenty-first century. This chapter provides an overview of the principles, experimental designs, and research progress on solar-hydrogen production via the water-splitting reaction on photocatalyst surfaces. The concept of using solar energy to drive the conversion of water into hydrogen and oxygen is examined from the standpoint of both energy requirements and factors that determine the activity of photocatalysts. A survey is presented of the advances made in the development of catalysts for photochemical water splitting under visible light since the pioneering work by Fujishima and Honda in 1972. Photocatalysts for water splitting under ultraviolet light have made remarkable progress in recent years, but there are many technical challenges, mainly the low efficiency in light-to-hydrogen conversion, still facing photocatalysts under visible light. There are still major challenges in the development of photocatalysts with improved efficiencies for hydrogen production from water using solar energy. An overview is provided in this chapter about research strategies and approaches adopted in the search for photocatalysts for water splitting under visible light (new photocatalyst materials and the control of the synthesis of materials for customizing the crystallinity, electronic structure, and morphology of catalysts at nanometric scale).