Research On Photoelectrochemical Sensor Based On P-type Semiconductor PbS And Its Heterostructure

In recent years,photoelectrochemical detection technology has been widely studied in many fields such as chemistry,medicine,food,environmental monitoring,and biology because of the advantages of high sensitivity,simple equipment,and easy miniaturization.Photosensitive materials are the basis of photoelectrochemistry.Among many materials,narrow-bandgap p-type semiconductors have been the focus of research in recent years due to their excellent anti-interference ability in the coexistence of reducing substances.In this paper,based on the p-type semiconductor Pb S,two PEC sensing platform with signal amplification induced by use of specific electron acceptors and formation of heterostructure were developed.1.A cathodic photoelectrochemical(PEC)sensor was proposed for high sensitive determination of Cr(?)under visible-light irradiation.Here,mercaptoacetic acid(TGA)-capped Pb S quantum dots(QDs)was assembled on the surface of indium tin oxide(ITO)via linker-poly diallyl dimethyl ammonium chloride(PDDA)as a photoactive electrode.Cr(?)could accept the photoelectron generated by Pb S QDs,promoting electron-holes separation and enhancing cathodic photocurrent.The proposed system achieves high sensitivity of 0.01 n M and wide linear concentration range from 0.02 n M to 2 ?M for sensing Cr(?).Meanwhile,this sample method was successfully applied to detect Cr(?)and total Cr element in environmental water samples.2.A novel PEC bioanalysis platform was developed based on the double signal amplification by lead sulfide(PbS)quantum dots and Co3O4 nanoparticles forming heterostructures and the catalytic effect of Co3O4 nanozymes.Water-soluble mercaptosuccinic acid(DMSA)-modified Co3O4 nanoparticles were prepared,and the Co3O4 nanoparticles were assembled on the outer layer of Pb S quantum dots to form pp type heterostructure using electrostatic adsorption.The photoelectric conversion efficiency of Pb S quantum dots was greatly improve and it achived about 2.8 times.What's more,in neutral and alkaline conditions,Co3O4 nanoparticles can catalyze the decomposition of H2O2 to produce electron donors(oxygen).Oxygen can accept photoelectrons of the Pb S QDs,which suppressed the recombination of electron-hole pairs and further enhanced the photocurrent response.On the base of Pb S / Co3O4 hybird nanostructure as well as its application for novel self-powered cathodic photoelectrochemical(PEC)sensing,the developed PEC bioanalysis platform was used for H2O2 detection.Under the applied potential of-0.2V and the light irradiation of 470 nm,the sensor had a good linear response to H2O2 with a liner range of 5-250 ?M,and the detection limit was eatimated to be 1.13 ?M(S/N=3).In addition,Co3O4 nanozyme instead of biomimetic enzymes has been used for photoelectrochemical sensors for the first time,expanding the development of new PEC sensing platform.