The Preparation Of Copper Hexacyanoferrate/Carbon Nanomaterials Composite Modified Electrode For Photoelectrochemical Detection

Hydroquinone (1,4-dihydroxybenzene, HQ), an important chemical material andintermediate in organic synthesis, is widely used in the cosmetics, food, pesticide,pharmaceutical, chemical and other fields. Because it is difficult to degrade in the ecosystem, ithas become a kind of important environmental pollutants. So it is necessary to develop a simple,low cost, rapid and sensitive analytical method for the detection of micro-amount HQ.Electrochemical methods have attracted more attention due to the advantages of fastresponse, low cost, high sensitivity and selectivity, so many experts are committed to the studyof using this method for electrochemical detection. The transition metal hexacyanoferrate has thethree-dimensional inorganic polymer network structure with zeolite characteristics, and it iswidely concerned for its excellent electrocatalysis, metal cation storage, ion exchange selectivity.Carbon nanomaterials, especially the graphene and ordered mesoporous carbon, as a new type ofmaterials, have high application value, because of its unique electronic, mechanical, thermalproperties, large specific surface area and low cost etc.This article mainly is the preparation of photoelectrochemical sensors, based on siliconelectrodes modified with copper hexacyanoferrate composite combined with carbonnanomaterials. We adopt chronoamperometry to detect hydroquinone and catechol using twoelectrodes system and rule out the interference between the two isomers with the aid of theexcellent properties of carbon nanomaterials, improving the sensitivity, selectivity and stabilityof the sensor.The content of this study mainly includes the following three parts:1. Hydroquinone sensors based on CuHCF/Pt/n-n+-Si photo-electrodeThe stable film of CuHCF was electrochemically deposited onto a phosphorus heavy dopedsilicon (n+-Si) with9μm epitaxial layer (n-n+-Si) wafers coated with about40nm platinum layer(Pt/n-n+-Si). Inverted metallurgical microscope, scanning electron microscope (SEM), x-ray photoelectron spectroscopy (XPS) and Fourier infrared spectrum (FTIR) were used tocharacterize the morphology, composition and photoelectrochemical behavior of the CuHCFfilm. A two electrodes cell based on CuHCF/Pt/n-n+-Si electrode was used as sensor for HQdetermination by chronoamperometry at a zero bias. The sensor showed good photocurrentresponses by adding different concentrations of HQ with a good stability. The linear range forthe detection of HQ was1.0×105to2.0×104M, with a detection limit (S/N=3) of2.2×106M.The new photoelectrochemical sensor provides a direction to the research of portable sensors.2. Catechol (CC) sensors based on CuHCF/GR/Pt/n-n+-Si photo-electrodeThis section presents the graphene/copper hexacyanoferrate modified electrodes based onsilicon for photoelectric detection of catechol. The silicon (n+-Si) with9μm epitaxial layer(n-n+-Si) wafers were coated with about40nm platinum layer (Pt/n-n+-Si) on the front and about500nm aluminum layer on the back.We use graphite oxide reduction method to preparegraphene, graphene oxide was prepared by Hummers, graphene was prepared by hydrazinehydrate reduction method.We use the drop coating method to put10μL solution of dimethylformide/graphene on the electrode surface, and use the cyclic voltammetry to form copperhexacyanoferrate film. Metallurgical microscope, scanning electron microscope (SEM), andx-ray photoelectron spectroscopy (XPS) were used to characterize the morphology, compositionand photoelectrochemical behavior of the CuHCF/GR film. The sensor showed goodphotocurrent responses by adding different concentrations of CC with a good stability. The linearrange for the detection of CC was20-220μM, with a detection limit (S/N=3) of1.8×106M andthe correlation coefficient of0.99353. The performance improvement of HQ sensor via ordered mesoporous carbao(OMC)/copper hexacyanoferrate hybrid modified n-silicon electrodeThe third part of this paper shows the omc/copper hexacyanoferrate modified electrodesbased on silicon for photoelectric detection of catechol. We use the drop coating method to put10μL ordered mesoporous carbon DMF solution on the electrode surface, and prepare copperhexacyanoferrate film by cyclic voltammetry. Scanning electron microscope (SEM), and x-rayphotoelectron spectroscopy (XPS) were used to characterize the morphology, composition andphotoelectrochemical behavior of the CuHCF/OMC film. The sensor showed good photocurrentresponses by adding different concentrations of HQ with a good stability. The linear range for the detection of HQ was20-140μM, with a detection limit (S/N=3) of1.8×106M and thecorrelation coefficient of0.9969. And the sensor eliminates the interference of catechol to thedetection of HQ. It is a breakthrough in this experiment to enhance the selectivity of sensor. Atthe same time, we use the multimeter to detect HQ in the sunshine, which indicates that thesensor is suitable for application outdoor.