Preparation And Application Of Photoelectric Materials Based On TiO₂ Nanotube Arrays

Nanomaterials show special physical and chemical properties which are different from conventional materials,due to their size in the nanometer range?1-100 nm?.Nanomaterials have been widely used in the fields of catalysis and new generation biosensor designs.In this paper,the determination of cytochrome C as the target,while the development and modification of TiO₂ nanomaterials focus on the development of nano-composite based on titanium dioxide in biosensor research,the specific research as follows:?1?Preparation and photoelectric properties of CdS/Au/TiO₂ nanocomposites.We first prepared the TiO₂ nanotube arrays?NTAs?by anodic oxidation method,then Au nanoparticles?Au NPs?with average size of about 5-20 nm were deposited onto the TiO₂ nanotube substrate by pulse electrodeposition,and CdS quantum dots?QDs?was deposited on the Au/TiO₂ photoelectrode by successive ionic layer adsorption and reaction?SILAR?technique,thus CdS/Au/TiO₂ nanocomposites were successfully prepared.The combination of CdS?2.24 eV?and TiO₂?3.2 eV?can construct a step-like bandedge structure.This step-like bandedge structure can greatly enhance the photon absorption of the material,promote the photocurrent generation and show good photocatalytic activity.The immobilization of Au NPs can be used to increase the photoconversion efficiency of TiO₂ nanotubes due to the strong surface plasmon resonance effect?SPR?.CdS/Au/TiO₂ nanomaterials solve the problem of low visible light utilization efficiency of TiO₂ NTAs,and have high efficiency charge transfer performance.Compared with TiO₂ NTAs,CdS/Au/TiO₂ NTAs shows good photoelectric properties and the photocurrent intensity is significantly enhanced.The highest photocurrent density?7.08 mA/cm2?was achieved on the 4CdS/Au/TiO₂ NTAs photoelectrode.In addition,we selected the organic pollutant 2,4-dichlorophenoxyacetic acid?2,4-D?as the target molecule,the photocatalytic degradation of 2,4-D by 4CdS/Au/TiO₂ NTAs composite electrode was carried out and its good photocatalytic performance was verified.The experimental results show that the pollutants 2,4-D are completely degraded after 2 h continuous light irradiation.The degradation efficiency of 4CdS/Au/TiO₂ NTAs nanocomposites decreased from 100%to 86.5%after 5 cycles of 2,4-D continuous cycles.In general,4CdS/Au/TiO₂ NTAs nanocomposites have good chemical stability.?2?Detection of cytochrome c by unlabeled photoelectric sensor based on the 4CdS/Au/TiO₂ NTAs photoelectrode.The 4CdS/Au/TiO₂ NTAs photoelectrode with excellent photoelectric conversion efficiency and high stability were used as substrates.On this basis,the cytochrome c?cyt c?specific aptamers with mercapto groups were modified on the 4CdS/Au/TiO₂ NTAs photoelectrode,and the unlabeled photoelectrochemical?PEC?aptasensor was constructed for the quantitative detection of cyt c.Principle of the PEC aptasensor:Due to the specific recognition between the mercapto-aptamer and cyt c,cyt c binds to the aptamer to form a complex,which results in a strong steric hindrance effect,thus causing changes in the sensor photoelectric signal.Quantitative analysis of cyt c by measuring the change in photocurrent,which results in a low detection limit and a high selectivity due to the specific binding between the aptamer and the cyt c.The experimental results show that the PEC aptasensor shows high selectivity and sensitivity with a LOD of 3.45 pM and a linear range of 5 pM to 100 nM.In addition,further experimental data show that the PEC aptasensor has good reproducibility and stability.