| Heavy metal pollution in water and other ecosystems is one of the major environmental issues and has received worldwide attention.In order to monitor heavy metals in environmental ecosystems,electrochemical sensors are becoming increasingly popular due to their high sensitivity and ease of use.Due to its large specific surface area and abundant active sites,nanomaterials can further improve the sensitivity of electrochemical detection of heavy metals in electrochemical sensor components.Therefore,the use of electrochemical methods to detect heavy metal ions has attracted more and more attention.However,a single precious metal nanocatalyst is expensive and expensive.Therefore,in this paper,the preparation of bimetallic nanocatalysts is compared with single metal nanocatalysts,aiming to reduce the amount of precious metals,increase the catalytic activity,and improve the sensitivity and practicability of the modified electrode of the catalyst.The main research contents and conclusions of this topic are as follows:?1?The introduction part first explains the background of heavy metal pollution sources and hazards,as well as methods for detecting heavy metal ions.Then introduce the application,working principle,development history and classification of electrochemical sensors.At the same time,the preparation methods,carrier selection,research and application in electrochemical sensors and other fields in nanomaterials are discussed.?2?Palladium catalyst?Pd/C?with activated carbon as carrier was prepared by microwave assisted polyol method.Cyclic voltammetry was used.The electrochemical test interval ranged from-0.8 to 0.4 V,and the scanning speed was0.05 V/s.In addition,the effect of the palladium catalyst prepared by using graphene as a carrier and the palladium catalyst prepared by different alkaline environments were investigated.The preparation conditions of the palladium catalyst with good voltammetric curve performance are summarized.It was found that the prepared palladium catalyst had the best catalytic effect when activated carbon was used as the carrier and 3.8 mL of KOH solution was added dropwise and heated in a microwave oven for 1 min.X-ray diffraction?XRD?and transmission electron microscopy?TEM?results show that the Pd nanoparticles in the palladium catalyst are highly dispersed on the surface of the activated carbon,and the average particle size is 5.26 nm.Chronoamperometry?CA?,Cyclic voltammetry?CV?and electrochemical alternating current?EIS?tests were performed to measure the image of the catalyst in methanol and ethanol.The peak current density obtained in ethanol was higher than that in methanol.High,showing better activity and stability.?3?A palladium-ruthenium nano-bimetallic catalyst?PdRu/C?prepared by activated carbon was prepared by microwave assisted polyol method.Transmission electron microscopy?TEM?results show that when Ru is added,the catalyst can obtain better dispersibility and smaller grain radius,and the PdRu/C catalyst has a smaller average grain size.XRD data indicates that Pd-Ru is successfully supported on activated carbon as an alloy.The catalytic performance was determined by analyzing the oxidation and reduction peaks of methanol and ethanol at different molar ratios of PdRu.The PdRu/C catalyst exhibited good CO tolerance.In addition,all catalysts showed better electrocatalytic oxidation performance than ethanol in methanol under alkaline conditions.The current intensity of the PdRu?1:1?/C catalyst used for the electrooxidation of ethanol reached about 991 mA·mg-1 Pd;while the methanol was only 375 mA·mg-11 Pd.Further,the catalytic performance of PdRu?1:1?/C for the electrooxidation of an alcohol was 1.1 times that of the Pd/C catalyst synthesized in the same manner.The current intensity of PdRu?1:1?/C is slightly higher than Pd/C,and exhibits excellent durability after a long period of ethanol oxidation test.It also has a very fast charge transfer rate as shown in the Electrochemical AC Impedance?EIS?test.?4?Study the current response intensity of different kinds of modified electrodes for Pb???,including:bare glassy carbon electrode,Nafion modified glassy carbon electrode,Pd/C nanocatalyst and Nafion modified glassy carbon electrode,and PdRu/C nanocatalyst and Nafion The modified glassy carbon electrode,in which the PdRu/C nanocatalyst and the Nafion modified glassy carbon electrode exhibited the best current response effect.Then,through the CV diagrams of Pd/C and PdRu/C modified electrodes in different concentrations of lead ion solution,it is observed that the lead-ion reduction peaks of both of them increase with the increase of concentration,and the reduction peak shifts to the right.phenomenon.The detection limits of the Pd/C and PdRu/C modified electrodes were 1.65×10-4 g/mL and3.31×10-5 g/mL,respectively.And the CA diagram also shows that the peak current is proportional to the concentration.The linear equations and correlation coefficients of current and lead ion concentration are obtained by fitting the data.In addition,we conclude that the stability and reproducibility of the catalyst are high by repeated experiments and relative experimental standard deviation?RSD?.Finally,we tested the laboratory tap water samples and confirmed the potential of the catalyst for practical applications. |
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