| It is well known that metal oxides are the kind of semiconductor materials with specialphysical and chemical properties, and are the basis for the development of functional devices. Metaloxides have important applications in areas such as optics, optoelectronics, sensors, photocatalysis,dye-sensitized solar cells and so on. Due to various morphologies, unique structures, variable cationvalence and controllable oxygen vacancy of metal oxides, it can provide suitable space forproducing new materials with unique properties. With the development of science, pure metaloxides can not meet the demands, thus the composite of metal oxides with noble-metals, othersemiconductor nanomaterials, carbon materials are appeared to expand theirs applications. Noble-metals such as Au, Pt, etc. have good conductivity and high visible-light absorption capacity, sonoble-metals doping into metal oxides can be not only as an electron capture agent which caneffectively prevent the recombination of electron-hole pairs, but also as the light capture agentsenhance visible light absorption intensity of metal oxides. Thus the optoelectronic applications ofcompositions are broader than metal oxides, and the performance of compositions are better thanmetal oxides. Among various metal oxides, tin oxide (SnO2) and cerium oxide(CeO2) with excellentoptical properties are considered to be the most promising functional materials, which are typicaln-type wide band gap semiconductors. Considering their importance in functional devices in thefuture, SnO2and CeO2were determined to be research contents during my undergraduate period.This article is committed to demonstrate the synthetic methods and optoelectronic applications ofthese two metal oxides composition.The main contents and research results are as followed:1. Au-SnO2hybrid nanospheres (HNSs) were synthesized by a facile, one-step method, which wasachieved via a redox reaction between the reductive stannous (II) ions and oxidative auric (III)ions, and then in situ formation of Au nanoparticles (NPs) and SnO2NPs. The results indicatedthat the Au NPs are able to trap electrons, improve the electron-hole pairs’ life, and enhance thevisible light absorption intensity that are all beneficial for enhancement of the visible lightphotoelectrochemical performance. The cysteine was chosen as a model molecular to fabricatethe photoelectrochemical biosensor. The biosensor displayed excellent analytical performancefor detection of cysteine with an extremely broad linear range from0.4μM to12mM), and alow detection limit (0.1μM). Therefore, the Au-SnO2HNSs will be a promising candidate forphotocatalysts, photoelectrochemical biosensor, and other photoelectric devices.2. Hydrothermal method without using any surfactant was used to prepare Au-SnO2compositehollow nanospheres. A divalent tin salt(SnCl2) and a trivalent gold salt(HAuCl4) solved acidicethanol solution reacting at180°C for18h obstained the production. Transmission electron microscopy (TEM) and scanning electron microscopy(SEM) were used to characterize thenanomaterials. The results showed that Au-SnO2composite hollow nanospheres obtained by thismethod with uniform size and uniform dispersion, were in the range of130-180nm. X-raydiffraction(XRD) tests confirmed the presence of Au and SnO2. Because of its good opticalproperties, the Au-SnO2hollow nanospheres were applied as the electrodes of dye sensitizedsolar cells (DSSCs).3. Using ethanol, ethylene glycol, water and other solvents as different reaction solution, throughhigh-temperature hydrothermal method synthesized CeO2nanocrystals with differentmorphologies. Potassium chloroplatinate solution was added by one-step method to obtainPt-CeO2nanocomposites with different morphologies. Since the noble metal Pt itself has goodconductivity, and thus the obtained composite by combing Pt with nano-CeO2had excellentelectrochemical properties. By peroxidase-like activity tests found that the peroxidase-likeactivity greatly influenced by the morphology. The Pt-CeO2nano-octahedron composites hadthe best peroxidase-like activity. |
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