Study On Electrochemical Detection Of Heavy Metal Ions In Water Based On Cerium-based Nanomaterials

The rapid development of industrialization has brought huge economic benefits to people,but corresponding environmental problems have emerged as The Times require.The most typical example is that industrial wastewater containing a variety of heavy metal ions(HMIs)is discharged into the environment.In natural water system,heavy metal ions in excess of a certain concentration will pose a great danger to humans and aquatic organisms.However,the heavy metals ions cannot be degraded but instead accumulate in organisms directly or through the food chain.Due to the strong toxicity of heavy metal ions,their accumulation in the organism can cause the disorder and damage of the organism.Therefore,the trace detection of heavy metal pollutants in water is particularly important.However,electrochemical methods have been widely used because of their advantages of rapidity and accuracy.Nanomaterials have been widely used in electrical analysis and detection.However,the structure-activity relationship between sensitive interface active sites and electrochemical sensing mechanism is not clear.Therefore,the physical structure and electrochemical sensing properties of nanomaterials exposed to different crystal surfaces and defects were systematically studied.The research contents of this paper are mainly carried out from the following aspects.(1)Cerium oxide nanorods were prepared by hydrothermal method,and then the ruthenium-supported cerium oxide nanorods(Ru/CeO2(nanarod))were prepared by water bath heating and stirring.It was characterized by XPS,Raman,EPR and other test methods,and SWASV was used to realize the highly sensitive detection of Hg(Ⅱ),with detection sensitivity of 1655.0 μA μM-1 cm-2 and detection limit of 0.02 μM.We think this kind of modified electrodes for Hg(Ⅱ)is the cause of the high sensitivity can be attributed to its exposed with a highly active surface of{110} plane,the existence of a large number of oxygen vacancies and ruthenium and provides more active site,good adsorption and catalytic activity,helps the electrochemical redox reaction occurred in the process of the work for the development of ruthenium load type nanometer metal oxide preparation and provides a good strategy.(2)Cerium dioxide nanocubes were prepared by hydrothermal method and calcined at 400,450,500,550 and 600℃ respectively to achieve the adjustment of oxygen vacancy concentration.Then,by combining XPS,EPR,UV-Vis,FTIR and other characterization with electrochemical experiments,a group of materials with the best electrochemical performance was obtained.Then,the ruthenium-supported cerium oxide nanocubes(Ru/CeO2(nanocubes))containing oxygen vacancy was obtained by heating the surface of ruthenium nanoparticles,which was further applied in the electrochemical detection of Hg(II).The adsorption experiments show that oxygen vacancy concentration is positively correlated with adsorption performance.The results showed that the detection sensitivity of Ru/CeO2(nanocubes)to Hg(II)was 2169.8 μAμM-1 cm-2 and the detection limit was 0.019 μM.This is mainly due to the abundant oxygen vacancies on the surface of Ru/CeO2(nanocubes)provide a large number of active sites and the relatively high activity of ruthenium nanoparticles,which enhance the adsorption of heavy metal ions,promote the electron transfer on the surface of the material,and enhance the redox process,thus improving the electrochemical performance.This work analyzes and designs fine sensing interface by modulating surface defects of nanomaterials,which provides a basis for the reliable detection of trace heavy metal pollutants.