Photocatalysis is important in fighting environmental pollution, such as pharmaceutical effluents, dyes, pesticides and endocrine disruptors. It is also used for the production of clean energy, e.g. by way of hydrogen production from watersplitting, or CO2 conversion into fuels. Further, photocatalytic N2 fixation is promising for achieving sustainable ammonia synthesis. The book discusses new materials and reaction engineering techniques, such as heterojunction formations, composites, ion exchangers, photocatalytic membranes, etc.