Research And Application Of Electrochemiluminescence Based On Carbon Nitride Nanomaterials

Graphite carbon nitride(g-C₃N₄)as an excellent semiconductor photocatalytic material has attracted widespread attention due to its large specific surface area,excellent physical and chemical stability,excellent electronic band structure,and excellent optical,electrical and mechanical properties.In addition,g-C₃N₄nanomaterials have good biocompatibility,and it has potential application value as biosensing materials.Based on the excellent photoelectric properties of g-C₃N₄,we further studied its electrochemiluminescence behavior,and used the g-C₃N₄ECL system for the detection and analysis of vitamin B in serum.This method is compatible with traditional biology,fluorescence analysis,immunoassay and high efficiency.Compared with liquid chromatography,it has the advantages of high sensitivity,low background interference,and low detection limit.The ECL system has achieved good experimental results in the detection of VB₆,VB₉and VB₁₂in actual samples.The specific experiment in this paper is divided into the following three parts:1.Synthesis and Characterization of Graphite Carbon Nitride Nanosheets(CNNS)Using melamine as the precursor,the bulk graphite phase carbon nitride material was synthesized by thermal polycondensation method,and the bulk carbon nitride material was ultrasonically peeled off in"green solvent"water to prepare CNNS.Structural characterization through a series of technologies such as SEM,TEM,FT-IR,XRD,UV-DRS,etc.,proved that we successfully synthesized CNNS with a relatively uniform size,modified CNNS on the electrode,and constructed a cathode ECL system in an aqueous environment.According to electrochemiluminescence exploration,the ECL signal is significantly enhanced than that of bulk carbon nitride materials.2.The ECL sensor of CNNS material is used for the detection of vitamin B₁₂in human serumThe"green solvent"method peels off the bulk carbon nitride material to form an ultra-thin CNNS.In the presence of the co-reactant K₂S₂O₈,a strong and stable electrochemical signal can be generated at-1.18 V(vs Ag/Ag Cl).The luminescence signal is about 3 times stronger than the traditional bulk carbon nitride material.Further electrochemical studies have shown that the addition of VB₁₂has a strong sensitizing effect on CNNS,which can greatly improve the electrochemical signal of CNNS.Therefore,CNNS synthesized by the"green solvent"method can be used as an ECL sensor to achieve rapid and sensitive detection of VB₁₂,with a detection line as low as38.2 pmol·L^-1.And it is found that this material has high sensitivity,anti-interference and applicability for the detection of VB₁₂in human serum,which proves the practicability of the sensor in actual samples.3.Wet ball milling method to synthesize CNNS-12 h for electrochemical detection of VB₆and VB₉In the experiments in this chapter,we proposed a simple wet ball milling method to exfoliate the bulk carbon nitride into CNNS.Cetyltrimethylammonium bromide(CTAB)surfactant is used to greatly improve the stripping efficiency of bulk carbon nitride.Changing the time of wet ball milling is an effective method to control the size and thickness of carbon nitride nanosheets and the level of edge defects.With the increase of ball milling time,the active area is enlarged and the catalytic ability is improved,thus giving it excellent electrochemical reactivity.Set the ball milling time to 4 h,8 h,12 h,16 h,and the stripped carbon nitride materials were named CNNS-4 h,CNNS-8 h,CNNS,CNNS-12 h,CNNS-16 h.Chemical characterization,CNNS-12 h has the most excellent electrochemical signal.The electrochemical detection of VB₆and VB₉can be performed separately,and the detection limits of VB₆and VB₉are as low as 89.66nmol·L^-1and 2.10 nmol·L^-1,respectively.Therefore,the proposed strategy opens up a new way for adjusting the electrochemistry of carbon nitride materials and designing new applications.