Plasmonic effect on visible light driven photoelectrochemical activity of semiconductor

• Main Author: Zhang, Huanchao
• Other Authors: Zheng Lianxi
• Format: Final Year Project
• Language: English
• Published: 2013
• Subjects: DRNTU::Engineering::Materials
• Online Access: http://hdl.handle.net/10356/53444
• Institution: Nanyang Technological University

Solar energy has been widely recognized as the most promising future energy source owing to its continuity and abundance. Semiconductors have been intensively explored in harvesting solar energy in recent years, among which TiO2 attracts many interests essentially for its excellent photostability. Nevertheless, like other semiconductors, TiO2 responds only to ultraviolet excitation for its wide band gap. Noble metals, especially gold nanoparticles, have been introduced to overcome this shortcoming most recently because of plasmonic effect, which effectively improves semiconductor’s optical absorption and enhances its photoelectrochemical activity under visible spectrum. In this study, an alternating TiO2/Au/TiO2/Au/TiO2 layered composite was prepared, whose morphology was imaged under SEM machine subsequently to ensure a uniform distribution of gold nanoparticles inside TiO2 matrix. Gold nanoparticles heat-treated at 600°C for 1 hour were tested to achieve the highest regularity in morphology. In addition, absorption spectra for one to five-layer structures were measured, demonstrating that five-layer TiO2/Au composite increased the absorption capability of TiO2 over visible spectrum the most. A maximum absorption enhancement ratio of 11.5 was obtained at wavelength of 675nm. Meanwhile, photoelectric behavior test exhibited a 43-fold increase in photocurrent density upon visible illumination for five-layer structure, suggesting an intensively improved photoelectrochemical reaction with the aid of structured gold nanoparticles. It was concluded that plasmonic effect did help TiO2 enhance its photoelectrochemical activity under visible spectrum and 3D alternating layered structure achieved a superior performance, worth being developed further in future studies.