N-type Silicon Photovoltaic Research Chemical Sensing Electrode Modified Nickel Oxyhydroxide

Nano photoelectrochemical sensor is a novel and composited sensing device thatis based on the conversion of light energy into electricity and nano effect, light is usedto excite active species on the electrode, and current or voltage is obtained as thedetection signal which concerned with concentration of the material and parameters ofrelated biological processes within a cell in photoelectrochemical detection. Due to itssimplicity, flexiblility, convenient operation and the unique advantages and broadapplication prospects in aspects of biological identification and analysis testing, it isvery important in research and application value.This thesis mainly investigates kinds of nano photoelectrochemical sensor basedon characteristics of photoelectrochemical sensor and nickel hydroxyl-oxide. Severaldifferent types of nickel hydroxyl-oxide films have been modified on the surface ofn-n+-Si electrode by vacuum vapor or electrochemical plating technology. Themodified electrodes have been used for determination of hydrogen peroxide orhydroquinone with a two-electrode cell in absence of reference electrode byphotocurrent measurement at a zero bias. Experimental study includes the followingthree contents:1. Nickel hydroxyl-oxide modified n-silicon photoelectrode for hydrogen peroxidedetection in an alkaline solutionA novel photoelectrochemical hydrogen peroxide (H2O2) sensor was constructedwith platinum (Pt) and nickel hydroxyl-oxide (NiOOH) double layers modifiedn-silicon electrode (NiOOH/Pt/n-n+-Si). About40nm Pt layer and about100nm Nilayer were successively coated on the front surface of n–n+–Si (111) wafers byvacuum evaporating. A stable layer of NiOOH was formed through oxidation of theNi layer on the coated silicon wafer by electrochemical method. The surface ofmodified electrode was characterized by scanning electron microscopy (SEM) andx-ray photoelectron spectroscopy (XPS). The NiOOH/Pt/n-n+-Si electrode has beenused for determination of H2O2with a two-electrode cell in absence of referenceelectrode by photocurrent measurement at a zero bias. The photoelectrochemical sensor showed a good linear response to H2O2concentrations in a range from1.0×105to6×105M with a determination limit (S/N=3) of2.2μM. TheNiOOH/Pt/n-n+-Si electrode exhibited excellent reproducibility and stability.Particularly, the facile measurement requirements made this novel modified electrodepromising for the development of outdoor H2O2sensors.2. Electrodeposited nickel hydroxide ayers modified n-silicon photoelectrode forhydrogen peroxide determinationA novel photoelectrochemical and non-enzymatic hydrogen peroxide (H2O2)sensor was fabricated by electrochemically cathodic plating nickel hydroxide(Ni(OH)2) on platinum films coated n-silicon (Pt/n-n+-Si electrode). Nickelhydroxyl-oxide (NiOOH) films on the Pt/n-n+-Si electrode were formed by cyclicvoltammetry in0.2M KOH solution. The morphology and composition of NiOOHfilm were characterized via scanning electron microscope (SEM) and X-rayphotoelectron spectroscopy (XPS), respectively. A two-electrode cell based onNiOOH/Pt/n-n+-Si electrode and a platinum counter has been used for determinationof H2O2in absence of reference electrode by photocurrent measurement at a zero bias.In these conditions a sensitivity of96.9μA mM-1cm-2and a linear response rangefrom0.02up to0.16mM with a determination limit (S/N=3) of5.4μM were achievedin KOH solution at pH13.3. In addition, the electrode also exhibited superior stability,anti-interference and selectivity.3. Determination of hydroquinone based on nickel oxide hydroxide/gaphenemodified n-silicon photoelectrodeA novel photoelectrochemical hydroquinone (HQ) sensor was developed bynickel hydroxide (Ni(OH)2)/grapheme sheets (GR) double layers modified Pt/n-n+-Sielectrode, and a NiOOH film was deposited by electrochemical method on the surfaceof GR coated Pt/n-n+-Si electrode by chemical method. Nickel hydroxyl-oxide(NiOOH) films on the GR/Pt/n-n+-Si electrode were formed by cyclic voltammetry in0.2M KOH solution. The morphology and composition of the surface ofNiOOH/GR/Pt/n-n+-Si were characterized by scanning electron microscope (SEM),Fourier transform infrared (FTIR) spectra and X-ray diffraction (XRD). Based on a two-electrode cell without reference electrode (NiOOH/GR/Pt/n-n+-Si and Pt) and azero bias, the modified electrodes show a better linear response range from0.01up to0.06mM with a determination limit (S/N=3) of3.6μM compared withNiOOH/Pt/n-n+-Si. In addition, the modified electrodes also show goodanti-interference and selectivity on the detection of its isomers.