CHAPTER 5: Photoexcitation in Pure and Modified Semiconductor Photocatalysts

Semiconductor photocatalysis has great promise for applications in solar energy conversion and environmental remediation because it is inexpensive, versatile, and environmentally benign. However, some critical factors such as limited light absorption and fast electron–hole pair recombination restrict the practical applications. Because no pure-phase semiconductors efficiently utilize solar irradiation, semiconductor materials have been modified in various ways to enhance their light-absorption properties. In this chapter, photoexcitation in modified semiconductor systems that include the impurity-doped, coupled, dye-sensitized, ligand-to-metal charge transfer (LMCT)-sensitized, and local surface plasmon resonance (LSPR)-sensitized semiconductors are discussed. In particular, the photoexcitation mechanism, charge transfer pathway, applications, and limitations of each method are described.