| As a new analysis method,photoelectric chemical analysis is setting up by usingphotoelectrochemical process and chemibiological identification process.This method usedphotocurrent as a detection signal,which is generated from light excited active material on theelectrode surface.Because of its simple operation,fast response,high sensitivity and easyminiaturization,it is attracted great attention in the field of analysis and recognition of biologicalmolecules,detection and environmental analysis.Using the relationship between the variation ofthe photocurrent and detection substances, the variation of the photocurrent is caused by directidentification of redox and enzyme catalysis method, etc. Through modifying sensingrecognition unit in the photovoltaic layer, we can realized quantitative and qualitative analysisfor the target molecules.As a lovely byproduct of metabolism, hydrogen peroxide plays a key role in many reactionrelated nerve. In the field of food, clinical, environmental monitoring, water quality monitoring,etc, we can see the existence of hydrogen peroxide. So, quickly and accurately detectinghydrogen peroxide is very meaningful. As the basic structural unit of protein, amino acid is thematerial of synthesis protein in animal body. At the same time, amino acid plays an importantrole in medical, industrial, agricultural production. It is capable of detecting and separation ofvarious amino acid quickly is very important.In this paper, based on the characteristics of semiconductor silicon materials, platinum,nickel oxyhdroxide,we discussed two kinds of optoelectrochemical sensor based onsemiconductor silicon. First, platinum metal has been modified on the surface of n-n+-Sielectrode by vacuum vapor plating technology. Then, a identification substance unit is modifiedon the surface of metal platinum layer. Last, the modified electrode have been used fordetermination of hydrogen peroxide or glycin with a two-electrode cell in absence of referenceelectrode by photocurrent measurement at a zero bias. Experimental study includes the followingtwo contents:1. Performance improvement of hydrogen peroxide sensor via cadmium doped nickel oxidemodifying n-silicon electrodeA novel photoelectrochemical hydrogen peroxide (H2O2) sensor was constructed withplatinum (Pt) and Cd-doped nickel oxide double layers modified n-silicon electrode (Cd-NiO/Pt/n-n+-Si). About40nm Pt layer was successfully coated on the front surface of n-n+-Siwafers by vacuum evaporating technology. About500nm aluminum layer was coated on theback surface of n-n+-Si wafers by the same method. Last, a Cd-doped nickel oxide layer was modified on the surface of Pt/n-n+-Si electrode by electrochemical cathodic deposition.Cd-doped nickel hydroxyl-oxide (Cd-NiOOH) films on the Pt/n-n+-Si electrode were formed bycyclic voltammetry in0.2M KOH solution. The composition and morphology of the modifiedelectrode were characterized via X-ray photoelectron spectroscopy (XPS) and scanning electronmicroscope (SEM), respectively. A two-electrode system based on Cd-NiO/Pt/n-n+-Si electrodeand a double layers platinum plate counter has been used for determination of H2O2in absence ofreference electrode by photocurrent measurement at a zero bias. And the doping amount of Cdwas discussed, finally,we determined that3.5%doping amount of Cd have the best sensitivity in0.2M KOH solution (pH=13.3), the sensitivity is254.6μA mM-1cm-2. In this condition a linearresponse range from0.02up to0.12mM with a determination limit (S/N=3) of2.2μM. Inaddition, the modified electrode also exhibited superior stability, anti-inteference and selectivity.2. The determination of glycin by cadmium and cobalt double doped nickel hydroxyl-oxideelectrodeA novel none-enzyme glycin photoelectrochemical sensor was fabricated byelectrochemically cathodic plating Cd and Co double doped nickel hydroxide on platinummodified n-silicon. Cyclic voltammetry scanning was used for composition activation on theelectrode surface. The morphology and composition of Ni0.7Co0.2Cd0.1(OH)2layer werecharacterized via deverted metallurgical microscope and X-ray photoelectron spectroscopy(XPS),respectively. The modified electrode has been used for determination of glycin in absenceof reference electrode by photocurrent measurement. In those condition a linear response rangefrom0.2up to1.4mM wih a determination limit (S/N=3) of0.04mM were achieved in0.2MKOH solution. In addition, the modified electrode exhibited superior selectivity and commonstability, common anti-interference. |
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