Photoactive Materials

This chapter introduces and examines photoactive materials and their role in clean energy systems to address local and global environmental issues during the transition to a sustainable future. Some advantages and disadvantages of various photoactive materials and processing technologies, with a special prominence on photocatalytic hydrogen generation, are considered in this chapter. Societal, ecological, and financial characteristics of photoactive materials are kept in mind during the comparative assessment of various photoactive materials and processing technologies and hydrogen production options. This chapter provides key background information on photoactive materials including photocatalysts, photoelectrochemical (PEC) cells, photoelectrodes, and photoelectrode processing is presented. After that, solar driven hydrogen generation methods are explained more in depth in conjunction with comparative performance assessments. Later, photocatalytic hydrogen generation methods are presented, and the photocatalysis mechanism and principles are introduced. Some of the main photocatalyst groups, specifically titanium oxides, cadmium sulfides, zinc oxides and sulfides, and other metal oxides are investigated in details. Subsequently, photocatalyst recycling issues are explained and comparative performance assessment criteria are introduced as hydrogen production rates (both per mass and surface area of photocatalysts), band gaps, and quantum yields.