Dissertation
Dissertation > Mathematical sciences and chemical > Chemistry > Physical Chemistry ( theoretical chemistry ),chemical physics > Electrochemical,electrolytic,magnetic,chemical

A Study of Sensor Property Based on Cobalt and Nickel Hexacyanoferrate Modified Silicon Electrode

Author GaoZuo
Tutor LiHuaiXiang
School Shandong Normal University
Course Physical and chemical
Keywords silicon photo-electrode hexacyanoferrate photo-electrochemical sensor ascorbic acid hydrogen peroxide
CLC O646
Type Master's thesis
Year 2013
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Photoelectrochemical(PEC) sensor is a novel analytical method that is based onthe conversion of light energy into electricity within a cell in photoelectrochemicaldetection, light is used to excite active species on the electrode, and current isobtained as the detection signal. Due to its simple instrument and low-cost, it iswidely used in chemical and biological sensor.Compared with manyphotoelectrochemical active species, silicon materials becomes the great material forphotoelectrochemical sensor owing to its excellent capability for photoresponse,non-toxicity and ease of passivation and texturing. The transition metalhexacyanoferrate is widely applied in detecting mang biological molecules as afuctional film in electrochemical analysis, which exhibits excellent reversible redoxcenters and has electrocatalysis for redox molecules. According to these factors, wemake these species modified in Pt/n-n+-Si photoelectrode and design threephotoelectrochemical sensors for detecting two important molecules-ascorbic acid andhydrogen peroxide in biological systems.This thesis mainly investigates three kinds of photoelectrodes based on siliconwafers.Combining wih the vacuum vapor deposition technique,three kinds iftransition metal hexacyanoferrate films were modified in the surface of n-n+-Siwafers with chemical method or electrochemical method.Then the modifiedselectrodes have been used for determination of ascorbic acid or hydrogen peroxidewith a two-electrode cell in absence of reference electrode by photocurrentmeasurement at a zero bias.This works demonstrates the feasibility of thephotoelectrodes,sensitivity of ascorbic acid or hydrogen peroxide sensors,andprovides an effective approach to detect ascorbic acid or H2O2.Experimental studyincludes the following three contents:1. A new ascorbic acid sensor based on CoHCF modified n-n+-Si photo-electrodeBy depositing a film of cobalt hexacyanoferrate (CoHCF) on silicon electrode coated by a platinum layer, a novel photoelectrochemical sensor for the detection ofascorbic acid (AA) has been developed. The stable film of CoHCF waselectrochemically deposited onto a phosphorus heavy doped silicon (n+-Si) with9μmepitaxial layer (n-n+-Si) wafers coated with about40nm platinum layer (Pt/n-n+-Si).Fourier transform infrared (FTIR) spectra, X-ray diffraction (XRD) and cyclicvoltammograms (CV) were used to characterize the CoHCF film on the Pt/n-n+-Sielectrode. The CoHCF modified Pt/n-n+-Si electrode has been used for determinationof AA with a two-electrode cell in absence of reference electrode by photocurrentmeasurement at a zero bias. The composite modified electrode demonstrated goodphotocurrent responses by adding different concentrations of AA. The linear rangefor the detection of AA was1.0×106to1.0×103M, with a detection limit (S/N=3) of1.0×106M. This provides a facile way of detecting AA and succeeds in avertingfrom inconvenient reference electrode. The emphasis is laid on that this modifiedsilicon electrodes can be used as sensors for the photocurrent determination of AAonly in two-electrode system without reference electrode at a zero bias. The use of theCoHCF modified Pt/n-n+-Si electrode as a AA sensor was demonstrated with goodstability and selectivity.2. Hydrogen peroxide sensor based on CoNiHCF/PANI modified n-Si electrodeBy depositing a film of Colbat-Nickel hexacyanoferrate (CoNiHCF)/PANi onsilicon electrode coated by a platinum layer, a novel photoelectrochemical sensor forthe detection of H2O2has been developed. The stable film of CoNiHCF/PANI waselectrochemically deposited onto a phosphorus heavy doped silicon (n+-Si) with9μmepitaxial layer (n-n+-Si) wafers coated with about40nm platinum layer (Pt/n-n+-Si).Scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectra,X-ray photoelectron spectroscopy and cyclic voltammetry (CV) were used to characterizethe CoNiHCF/PANI film on the Pt/n-n+-Si electrode. The CoNiHCF/PANI modifiedPt/n-n+-Si electrode has been used for determination of H2O2with a two-electrode cellin absence of reference electrode by photocurrent measurement at a zero bias. Thecomposite modified electrode demonstrated good photocurrent responses by addingdifferent concentrations of H2O2with a good stability. The linear range for thedetection of H2O2was2.0×106to1.16×10-4M with a detection limit (S/N=3) of1.0×106M. This provides a facile way of detecting H2O2and succeeds in averting frominconvenient reference electrode. 3. The performance improvement of H2O2sensor via graphene/nickelhexacyanoferrate hybrid modifying n-silicon electrodeA platinum (Pt) film coated n-silicon (Pt/n-n+-Si) was modified with graphemesheets (GS)/nickel hexacyanoferrate (NiHCF) hybrid and used asphotoelectrochemical sensor for enzymeless hydrogen peroxide (H2O2) detection. GSwere synthesized from flake graphite powder and coated on the surface of Pt/n-n+-Si.A NiHCF film was deposited on the surface of GS coated Pt/n-n+-Si electrode bychemical method. The morphology and composition of the surface of NiHCF-GS/Pt/n-n+-silicon were characterized by scan electron microscopy (TEM), X-rayphotoelectron spectroscopy (XPS), and X-ray diffraction (XRD). Thephotoelectrochemical (PEC) behavior of the resulting sensor was investigated usingcyclic voltammetry (CV) under illumination. The modified electrode and a Pt platecounter form a two-electrode cell and has been used as PEC sensor for H2O2detectionwith a linear range of2.0×10-6-2.9×10-3M and a detection limit of1.0×10-6at asignal-to-noise ratio of3. This provides a novel photoelectrochemical sensor for rapidsensitive technique of H2O2detection.

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