**Section 2 Photocatalyst for Photoreduction 127**

Chapter 8 **Photoreduction Processes over TiO2 Photocatalyst 129** Endang Tri Wahyuni and Nurul Hidayat Aprilita

Preface

Photocatalysts are based on nanomaterials and their applications are extremely broad. This is a constantly growing research area and it has become an important research topic in the recent years. Solar light photocatalysis is currently one of the most blossoming interdiscipli‐ nary fields of science. Research in the development of efficient photocatalytic materials has seen significant progress in the last two decades with a large number of research papers published every year. Improvements in the performance of photocatalytic materials have been largely correlated with advances in nanotechnology. As photocatalysts have diverse applications, the interest on photocatalysis has accelerated and has attracted worldwide in‐ terest. Photocatalysts have potential to be used in photodegradation of several contaminants to solve environmental problems. Other important applications of photocatalysts are the de‐ velopment of self-cleaning products, air purification, CO2 conversion to hydrocarbon fuels

Hence, photocatalysis is a subject of key interest. Therefore, it was planned to present recent progress in photocatalysis in the form of a book to the scientific community. There are eight chapters in this book. In the first chapter, different methods for disinfection such as chlorina‐ tion, zone, ultraviolet light, chloramines, potassium permanganate, photocatalytic disinfec‐ tion, nanofiltration, and chlorine dioxide are discussed. The second chapter is related to the selective degradations using a titanium-based photocatalyst while in chapter three, some of the most recent works that have employed the doping, decoration, and structural modifica‐ tion of TiO2 particles for applications in photocatalysis have been reviewed. Additionally, the effectiveness of these dopants and/or modifiers in enhancing TiO2 photoactivity as well as some perspective on the future of TiO2 photocatalysis are also discussed. Chapter 4 presents modified materials such as alternatives for conventional photocatalysts as titanium dioxide. Discussion about silver/graphene nanoparticle-modified zinc oxide for degradation of pollutants such as triclosan or bisphenol A, both considered as endocrine disruptors, which affect the hormonal development of humans, is presented. In addition, bismuth oxy‐ chloride has gained attention during the last 5 years for photocatalysis. In accordance, the obtained results for phenol photodegradation, using such oxychloride, are also presented. In the chapter, characterization of the photocatalyst is reported along with the proposal for mechanisms of action for the modified ZnO photocatalyst and bismuth oxychloride. In Chapter 5, structural modifications in semiconductors have been proposed to enhance the photocatalytic activity, such as doping processes with elements that are capable of generat‐ ing superficial defects that capture the formed electrons, avoiding the recombination or in‐ creasing the density of –OH groups or water molecules on the surface of the catalyst, which can enhance the formation of hydroxyl radicals. Therefore, this brief review is proposed to show the role of lanthanides in TiO2 doping and the synthesis method applied, as well as the

as well as the production of highly effective fuels such as hydrogen.
