This reference text covers the recent developments in the synthesis of BiOX and their applications in the production of energy and the purification of wastewater. The book begins with an overview of bismuth as well as bismuth oxyhalides and the fabrication process. It then reviews the state-of-the-art improvements in bismuth oxyhalides including elemental doping, surface modification and many others. Photocatalytic applications of bismuth oxyhalides along with their experimental and theoretical studies are discussed. The book also explores bismuth oxyhalides for wastewater treatment, reduction of carbon dioxide, and nitrogen fixation and finally, the various issues and potential solutions that could help with the development of effective photocatalytic bismuth oxyhalides.