Preparation Of TiO 2 /SrRuO 3 Heterojunction And Its Photoelectrochemical Performance Control

With the rapid development of economic and industry,environmental and energy issues draw more and more attention.Generally,solar energy is inexhaustible and non-polluting,and hydrogen fuel has high calorific value and its combustion products are environmental friendly.Thus,generating hydrogen through photocatalytic water splitting is one of the highlights in energy research area.By using photoelectrochemical cells?PEC?,which consists of semiconductor photoanode or photocathode and electrolyte,hydrogen could be obtained from water splitting and this is absolutely a sustainable,environmentally friendly method.Among the semiconductor electrode,TiO₂ is the first try to water splitting.Due to its excellent photoelectrochemical properties,chemical stability,non-toxic and low cost,TiO₂ is still the focus material in photoelectrochemical area.However,TiO₂ has several drawbacks,such as wide bandgap,short-lifetime,easy recombination of the photogenerated electron-hole pairs and the limited photo-responding range?only ultraviolet zone with 4% of the sunshine?.In this thesis,we designed TiO₂-based heterostructures by using ‘metallic' SrRuO₃ and La TiO3.The microstructure and surface morphology of these heterojunctions were characterized by AFM,SEM,XRD and XRR.Electrochemical impedance spectroscopy?EIS?,Mot-Schottky model,photoelectric current spectrum and photoelectric conversion efficiency spectrum were also used to characterize the photoelectrochemical properties.Our work provides a new way to understand and enhance the photoelectrochemical activity of TiO₂-based photoanode.The main contents in this work are listed as following:1.TiO₂/SrRuO₃ heterojunctions were growth by laser molecular beam epitaxy?L-MBE?technique.The thicknesses of TiO₂ and SRO layers were optimized by the photoelectrochemical study.The combination of ‘metallic' oxide with TiO₂ enables the production of heterojunctions that greatly outperform TiO₂ films alone.2.Interface dipoles were inserted into the TiO₂/SrRuO₃ heterojunctions for further controlling the Schottky barriers between TiO₂ and SRO.Low schottky barrier could greatly enhance the hot-electron injection.LaTiO3 with 0-4 u.c.was deposited on 30 nm SRO by L-MBE.The thickness was in-situ controlled by RHEED.3.To further enhance the PEC,Au nanoparticles were fabricated on the surface of TiO₂/SrRuO₃ heterojunctions by PLD assistant with annealing process.Due to the surface plasmon resonance effect,the photoelectric conversion efficiency of systems was enhanced greatly.