123rd General Meeting of the KCS

Type Symposium
Area Physical Chemistry Approaches in Energy and Environmental Materials
Room No. Room 401+402
Time FRI 15:40-16:00
Code PHYS3-4
Subject Promoting water photooxidation on transparent WO3 thin films using metal oxide overlayers
Authors Wooyul Kim
Department of Chemical and Biological Engineering, Sookmyung Women's University, Korea
Abstract Tungsten trioxide (WO3) is widely known as one of the most promising water photo-oxidation materials due to the visible range absorption. However, it has inherent limitation in the formation of peroxo species, stability and recombination of surface defect site. Nowadays it’s being gradually overcome by different methods, such as surface passivation, oxygen vacancy control and the chemically and physically deposition of co-catalysts. Here, WO3 (electrodeposited), Al2O3/WO3, and TiO2/WO3 (prepared by atomic layer deposition, ALD) electrodes were employed to investigate the role of the passivation overlayer by using both photoelectrochemical activity and laser flash photolysis measurements for charge carrier dynamic. It shows the different photoelectrochemical results based on passivation materials. In particular, femtosecond to microsecond transient absorption spectroscopy measurements of WO3, Al2O3/WO3, and TiO2/WO3 clearly showed that the ultra-fast pathway in the presence of the Al2O3 and TiO2 overlayer (ca. ps) under applied bias condition whereas the relatively long-trapped holes portion increased with overlayer (ca. s), facilitating water photooxidation. Moreover, we also carefully tuned oxygen vacancy of tungsten oxide form W to WO3 via WO2 using high temperature anodization method. Through the potassium contained non-aqueous anodization process, few amount of potassium can stabilize to oxygen vacancies in tungsten oxides. Various application of precise tuned tungsten oxide (e.g., both water oxidation and reduction process, oxygen reduction, etc) will be presented.
E-mail wkim@sookmyung.ac.kr