The Construction And Application Of Electrochemical Sensors Based On Two-dimensional Nanomaterials And Their Composites

Electrochemical sensors have been widely used in the fields of food inspection,clinical analysis,and environmental monitoring because of their advantages of simple equipment, low-cost and rapid signal response.To improve the sensitivity and anti-interference ability of electrochemical sensors,it is needed to explore novel nanomaterials with excellent properties which can be used to modify electrode.At present,two-dimensional nanomaterials, including transition metal sulfide?TMDs?and black phosphorus?BP?,have attracted much attention due to their excellent properties.In addition,it is found that composite materials can show synergistic effects on the basis of the advantages of a single component,resulting in a better comprehensive performance.In this paper,a variety of two-dimensional nanomaterials and their composites are synthesized,and their electrochemical properties are studied to expand their electrochemical sensing application.The main contents are as follows:1.Layeredmolybdenumdisulfide/reducedgrapheneoxide?MoS₂/RGO?nanocomposites were synthesized by solvothermal method.The electrochemical properties of the nanocomposites were studied by cyclic voltammetry and electrochemical impedance spectroscopy.Hydroquinone was selected as model molecular to investigate the electrochemical responses of the modified electrode.The results found that the synergetic effect of nanomaterials endowed the nanocomposite excellent electrocatalytic behavior towards the electrochemical reaction of hydroquinone.Under the optimal condition,hydroquinone can be sensitively detected in the range of 1-9 nM with the detection limit of0.3 nM?S/N=3?.The obtained results revealed MoS₂/GRO composites exhibited promising potential for electrochemical sensors.2.Black phosphorus nanosheets?BPNS?were synthesized through liquid exfoliation method coupling with ultrasonication.The results of characterization reveals that the BP nanosheets with an average size of 240 nm were obtained,which showed the high quality of the crystals.Compared with the bare electrode,the oxidation current of ascorbic acid increased nearly 6-times and the oxidation potential was negatively shifted,revealing that the BPNS exhibited excellent electrocatalytical effect on the oxidation of AA.Differential pulse voltammetry was used to detect AA in the range of 1-9 nM with a detection limit of 0.3nM?S/N=3?.3.Black phosphorus quantum dots doped ZnO nanoparticles?BPQDs@ZnO?were synthesized by simple hydrothermol method.The results show that the doping of BPQDs couldinhibit the further growth of ZnO nanorods,resulting in the apparent change of morphology.In neutral condition,the results revealed that BPQDs@ZnO exhibited the positive synergetic effect on the oxidation of H₂O₂,which can be used to construct sensor to sensitively detect H₂O₂.The sensor showed linear amperometric responses for H₂O₂ in the concentration range from 50?M to 0.5 mM with the sensitivity of 195.4?A mM^-11 cm^-2.Another linear range was obtained from 1 to 10 mM with the sensitivity of 401.7?A mM^-1cm^-2.The detection limit was evaluated as 2.5?M with the signal-to-noise ratio of 3.The sensor based on BPQDs@Zn O modified electrode exhibited good reproducibility and long-term stability and is applicable for the detection of real samples.