Study On The Applications Of Innovative Hybrid Nanomaterials In The Photoelectrochemical Sensing

Photoelectrochemical(PEC)analysis is developing rapidly in recent years.PEC is based on the photo-to-electric conversion resulting from electron excitation and subsequent charge transfer of a photoexcited material produced by an applied light.It is widely used in the analytical community due to its advantages such as low cost,simple instrumentation and high sensitivity.Photoelectrochemical sensing materials are important components of PEC sensors.The superior PEC active species are beneficial to improve the sensitivity of detection.As to single semiconductors such as n-type or p-type semiconductors,the efficiency of photo-to-electric conversion and charge transfer are not very good because some electron and holes will recombine with each other soon.The recombine of electron and holes could be reduced greatly using composite materials which were prepared by coupling of various semiconductors.Using composite materials,the photoelectric conversion efficiency can be improved,the photocurrent response is increased,and the sensitivity of the photoelectrochemical sensor is increased.Futhermore,the absorption of composite materials is generated in the visible region,which is beneficial for biological analysis.Thus,the composite materials have been used more and more in photoelectric analysis.This thesis reports the first preparation and characterization of hybrid PbS quantum dots(QDs)/nanoporous NiO films nanostructure as well as its application in novel self-powered cathodic photoelectrochemical(PEC)sensing.Specifically,the thioglycolic acid(TGA)-capped PbS QDs were synthesized and then assembled onto the hydrothermal-fabricated 3D NiO nanostructured films on the transparent indium tin oxide(ITO)-coated glass substrates,followed by the subsequent conjugation withthe glucose oxidase(GOx)as a model bio-catalyst.Favorable alignment existed between the NiO and PbS QDs,and the as-obtained p-type heterostructure was characterized by various techniques and showed good PEC activities.In the self-powered PEC biosensing of glucose,the system exhibited high sensitivity to the dissolved oxygen in the electrolyte and thereby a novel PEC enzymatic sensor for glucose with good sensitivity and high sensitivity was developed.Furthermore,this thesis also reported the first preparation and characterization of hybrid CdS QDs/TiO2 nanobelts(NBs)as well as its application in anodic PEC biosensing.Specifically,the TiO2 NBs were synthesized on the ITO-coated glass substrates thorough hydrothermal method,then the thioglycolic acid(TGA)-capped CdS QDs were assembled onto the TiO2 NBs.Favorable alignment existed between the TiO2 NBs and CdS QDs,and the as-obtained n-type heterostructure was characterized by various techniques and showed good PEC activities.The system exhibited high sensitivity and good selectivity to L-Cysteine.