This book concentrates on the emerging area of the utilization of (solar) photon energy for catalyzing useful chemical reactions (also called artificial photosynthesis) including water splitting, CO2 reduction, selective epoxidation, selective alcohol oxidation, coupling reactions, etc. The chapters in this book cover topics ranging from materials design at nanometer scale to nanomaterials synthesis to photocatalytically chemical conversion. This book can serve as a useful reference for those new to this field of research or already engaged in it, from graduate students to postdoctoral fellows and practicing researchers.