Preparation And Electrochemical Sensing Applications Of Two-dimensional Layered Composites

Two-dimensional layered materials represent an emerging class of nanomaterials,which have been widely used due to their high specific surface area,fast electron transfer,and easy preparation and exfoliation.Morevevr,this material can intercalate functional guest materials into the interlayer through intercalation to forming a new type of two-dimensional layered nanocomposites.The new nanocomposites not only have the unique structural characteristics of the host material,regular layered structure and stable physicalchemical properties,but also have the excellent properties of the guest material,which has great potential application value in the field of photoelectric catalysis,electrochemistry and biosensor.In this thesis,two-dimensional layered nanomaterials K₃Ti₅Nb O₁₄,Li Ta Mo O₆ and Go are selected as the host materials,and positively chared cationic pigments methylene blue and metal porphyrin（Mt TMPy P,Mt=Fe,Mn）are selected as guest material.The electrochemical properties of new two-dimensional layer nanocomposites formed between layered to the host material were investigated.The main research contents are as follows:1.Firstly,two-dimensional layered materials K₃Ti₅Nb O₁₄ and Li Ta Mo O₆ were prepared by traditional high-temperature solid-phase sintering method,and these materials were selected as two-dimensional layered host materials.Then,tetrabutylammonium hydroxide（TBAOH）was used to exfoliate the two-dimensional layered material into negatively charged nanosheets,and another host material,graphene oxide（GO）,was exfoliated into negatively charged nanosheets by ultrasonic-assisted method.The method of electrostatic self-assembly inserts methylene blue（MB）or metalloporphyrin（Mt TMPy P）into the interlayer to obtain MB/Ti₅Nb O₁₄,Fe TMPy P/Ti₅Nb O₁₄,Mn TMPy P/Ta Mo O₆ and MB/GO.In addition,the structure and morphology of these nanocomposites were characterized by X-ray diffractometer（XRD）,X-ray energy dispersive analysis（EDS）,scanning electron microscope（SEM）,transmission electron microscope（TEM）,X-ray photoelectron spectroscopy（XPS）,ultraviolet-visible spectroscopy（UV-vis）and infrared spectroscopy（FTIR）.2.The material was uniformly dropped on the surface of the glassy carbon electrode（GCE）by the drop coating method to make the modified electrodes MB/Ti₅Nb O₁₄/GCE,Fe TMPy P/Ti₅Nb O₁₄/GCE and Mn TMPy P/Ta Mo O₆/GCE,and then to study the electrochemical performance.The modified electrodes were tested by electrochemical impedance spectroscopy（EIS）,cyclic voltammetry（CV）and differential pulse voltammetry（DPV）.The experimental results demonstrate that the electron transfer ability of these novel nanocomposites is greatly improved,and the electrochemical oxidation performance of ascorbic acid（AA）,dopamine（DA）and uric acid（UA）is also nice.MB/Ti₅Nb O₁₄ and Fe TMPy P/Ti₅Nb O₁₄ nanocomposites can detect dopamine and uric acid,respectively.And they have lower detection limits of 2.01μM and 0.5μM,respectively,in the detection range of 0.0249 m M-0.4988 m M and 2.5μM-382μM,respectively.Mn TMPy P/Ta Mo O₆ nanocomposites can simultaneously detect ascorbic acid and dopamine.And MB/GO nanocomposites can be detected at the same time dopamine and ascorbic acid two substances,they have very low detection limit.In addition,the new nanocomposites synthesized have stable properties,good reproducibility and anti-interference ability,and are expected to be developed into highly sensitive electrochemical sensors against ascorbic acid,dopamine and uric acid.This paper has 111 figures,18 tables and 374 references.