This book presents the existing photocatalytic reactor design and the future developments and the progress needed for both solar light-driven hydrogen generation and environmental purification. The chapters discuss the renewable and commercial aspects of translucent polymer-linked heterojunction nanocomposites as visible light-responsive photocatalysts. Relevant to these areas, the field of growing interest in black-TiO2, perovskites, MXenes and their numerous applications are presented. The framework, structural features and the need of mesocrystals for solar light-driven photocatalysis are also included. The book also discusses the additional features of green chemistry-based synthesis of nanomaterials in order to reduce any secondary pollution that may be released in the environment due to unsafe disposal of solvents. In addition, the importance of bismuth-based nanophotocatalysts towards energy and environmental applications and their future development as alternative photocatalysts for the prevailing nanomaterials are presented. The book also touches upon the idea to generate green fuel hydrogen through photocatalytic and photoelectrochemical techniques. Overall the book highlights contemporary developments in the last decade, the future perspectives of photocatalysis and its application towards energy and environment.