Application Of Electrochemical Sensing Platforms Based On Transition Metal Phosphides

Transition metal phosphides（TMPs）have been widely applied in various fields such as electrochemical catalysis,energy storage,imaging and electrochemical analysis due to their good electrical conductivity and nonmetallic properties.Compared with other research orientations,there are few reports focusing on the application of TMPs in the field of electrical analysis,which provide the giant progress and profound value of research for this thesis.In the construction of electrochemical sensing platform based on TMPs,the type and topology of nanomaterials are crucial factors affecting the performance of the sensors.In this thesis,five electrochemical sensing platforms were fabricated based on the materials including TMPs,precious metals and foam metals for the determination of acetaminophen,p-nitrophenol,dopamine,hydrogen peroxide and hydroquinone respectively.By comparing the performance differences of the five electrochemical sensors,the general construction rules of electrochemical sensing platform based on TMPs are explored,which provide a reference for the fabrication of subsequent electrochemical sensing platform.The main contents of this thesis are as follows:1.Nickel phosphide nanosheets（Ni₂P NS）were modified onto glassy carbon electrode（GCE）to construct an electrochemical sensor for quantitative detection of acetaminophen for the first time.The theoretical calculation method was hired to predict possible reaction sites for acetaminophen.During the test,a current is generated by oxidation acetaminophen catalyzed by Ni₂P NS.The current is positively correlated with the concentration of acetaminophen,so as to realize its quantitative detection.The sensing platform based on Ni₂P NS demonstrates excellent performance:the linear range was 0.50–4500.00μM,the sensitivity was 131.10μA·m M^-1·cm^-2 and the detection limit was 0.11μM.Meanwhile,the sensor can be further applied to the determination of acetaminophen in commercial drugs with good recoveries.2.For the first time,tungsten phosphide nanoparticles（WP NPs）were modified on GCE to construct electrochemical sensor for quantitative detection of 4-nitrophenol.The potential reaction sites of 4-nitrophenol and sensing mechanism were discussed by theoretical calculation method.In the process of the experiment,a current is generated by oxidation4-nitrophenol catalyzed by WP NPs.The current is positively correlated with the concentration of 4-nitrophenol,so as to realize its quantitative detection.The sensor reveals excellent detection performance:the linear range was 10.00–6500.00μM,the sensitivity was89.76μA·m M^-1·cm^-2 and the detection limit was 1.59μM.At the same time,the sensor can be further applied to the determination of 4-nitrophenol in actual water systems,and reliable recoveries can be obtained.3.In order to conquer the obstacle of low sensitivity of the electrochemical sensor with adhesive agent in the above two sections,the three-dimensional cobalt phosphide nanowire array（Co P NWAs/TM）was first constructed directly on the conductive titanium mesh for quantitative analysis of dopamine.The potential reaction sites of dopamine were discussed by theoretical calculation method.During the experiment,a current is generated by oxidation dopamine catalyzed by Co P NWAs/TM.The current is positively correlated with the concentration of dopamine,so as to realize its quantitative detection.The sensing platform demonstrate reliable performance:the linear range was 1.00–3000.00μM,the sensitivity was 3366.00μA·m M^-1·cm^-2 and the detection limit was 0.36μM.Meanwhile,this sensor can be further applied to the determination of dopamine in serum and obtain good recoveries.4.Based on the research work in the previous chapters,the effect of bimetal synergy on the performance of electrochemical sensing platform was further investigated.The bimetallic nanoflower array with hierarchical structure（Co Ni P NF/TM）was first constructed on titanium mesh for quantitative analysis of hydrogen peroxide.The theoretical calculation method was hired to predict possible reaction sites for hydrogen peroxide.During the experiment,a current is generated by reduction hydrogen peroxide catalyzed by Co Ni P NF/TM.The current is positively correlated with the concentration of hydrogen peroxide,so as to realize its quantitative detection.The sensing platform demonstrates outstanding performance.Compared with the previously reports,the linear range of present sensor has been significantly improved nearly 5 times ranging from 1.00μM to 104.00 m M and the detection limit of 0.94μM.Furthermore,the sensor can be successfully employed for the determination of hydrogen peroxide in toothpaste and Tween-80 with reliable recoveries.5.In order to further improve the conductivity and synergistic catalytic performance of transition metal phosphide nanoarrays and upgrade the active sites of catalysts,a nickel phosphate nanosheet array modified by noble metal nanoparticles（Au/Ni₂P/NF NSAs）with porous lace edge was first time prepared and applied in for the quantitative detection of hydroquinone.The potential reaction sites of hydroquinone and synergistic catalytic mechanism were discussed by theoretical calculation method.During the experiment,a current is generated by oxidation hydroquinone catalyzed by Au/Ni₂P/NF NSAs.The current is positively correlated with the concentration of hydroquinone,so as to realize its quantitative detection.The sensing platform demonstrate excellent performance:the wide linear range was0.50–4000.00μM,the high sensitivity was 1715.00μA·m M^-1·cm^-2,the detection limit was0.26μM.In addition,the present sensing platform can be applied to hydroquinone determination in actual water environment with promising recoveries.