This book demonstrates the basic and fundamental aspects of nanotechnology and potential application as a photocatalysis in multiple application especially in environment and energy harvesting. This book also contains methods of preparation and characterization of unique nanostructured photocatalysts, and details about their catalytic action. The book consists of seven chapters, including the principles and fundamentals of heterogeneous photocatalysis; the mechanisms and dynamics of surface photocatalysis; research on pure and composites based materials with unique nanostructures; the latest developments and advances in exploiting photocatalyst alternatives to WO3; and photocatalytic materials for applications other than the traditional degradation of pollutants, such as carbon dioxide reduction, water oxidation, a complete spectrum of selective organic transformations and water splitting by photocatalytic reduction. This book will appeal to a wide readership of the academic and industrial researchers and it can also be used in the classroom for undergraduate and graduate students focusing on heterogeneous photocatalysis, sustainable chemistry, energy conversion and storage, nanotechnology, chemical engineering, environmental protection, optoelectronics, sensors, and surface and interface science.