The Synthesis, Characterization, and Application of Novel Photocatalytic Materials

Dear Colleagues,

A photocatalyst is a semiconductor that, when irradiated, adsorbs energy equal to or greater than its bandgap; therefore, a valence electron is excited into the conduction band, leaving a valence band hole behind. These photogenerated electrons and holes reach the surface of the semiconductor, where they reduce the species or act as oxidizing agents, respectively. Among all photocatalysts, oxide-based materials have been found to be more active, environmentally compatible and stable, with TiO₂ being studied thoroughly. Nevertheless, innovative photocatalytic materials synthesized through green approaches are being reported constantly. Challenging issues in the design of efficient photocatalytic materials include eliminating charge recombination, expanding light absorption over the ultraviolet region, and overcoming deactivation due to the adsorption of photodegradation reaction products on their surface. These novel photocatalytic materials can be applied to environmental remediation, such as water and wastewater treatment and reuse, or air and industrial gas stream treatment. They could also be utilized for potential applications in food preservation, water splitting, self-cleaning surfaces, or testing for antimicrobial properties.

Authors are welcome to cover any of the issues mentioned above according to their expertise.

Dr. Chrysoula Athanasekou
Dr. Nikolaos G. Moustakas
Guest Editors

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• visible/solar light harvesting
• advanced oxidation/reduction technologies
• water and wastewater treatment/reuse
• self-cleaning surfaces
• air treatment
• food preservation
• water splitting
• antimicrobial properties
• industrial gas stream treatment
• green synthesis

Title: Exploring metal modified TiO2-based Photocatalysts for Efficient and Sustainable Hydrogen Production
Authors: Apostolos Salepis; Emmanouil Orfanos; Athanassios G. Coutsolelos; A. Ch. Mitropoulos; Kalliopi Ladomenou
Affiliation: International Hellenic University, Department of Chemistry, Laboratory of Inorganic Chemistry, Kavala Campus, Agios Loucas, 65404, Greece
Abstract: The photocatalytic hydrogen production is one of the most promising approaches for sustainable energy production. In the literature there are a plethora of systems that have been carefully designed in order to use solar energy and convert it to chemical energy. The main drawback of the reported photocatalysts is their stability. Therefore, there is still the challenge to produce a cost-effective photocatalyst that could be used in real applications. Suitable photocatalysts for H2 production must have the appropriate band-edge energy positions. In addition, an important role plays the sacrificial agent and the use of cocatalysts. One photocatalyst that meets the above requirements and has been involved in a large number of studies is TiO2. In this review paper the principles of TiO2 and metal doped TiO2 photocatalysts were demonstrated. Platinum (Pt), gold (Au), copper (Cu), nickel (Ni), cobalt (Co), ruthenium (Ru), iron (Fe), silver (Ag) and bimetallic (Ni-Fe, Ni-Cu) are the TiO2 dopants that have been described. In all cases, H2 production efficiencies are greater compared to undoped TiO2, since the metals are able to provide more reaction sites and can improve the charge separation. In addition, the use of bimetallic dopants can further improve the H2 evolution reaction.