Application Of Graphene-based Nanomaterials And Metal-Organic Frameworks Composites For Electrochemical Sensors

Due to their advantages of high sensitivity,fast response,easy miniaturization,and low price,electrochemical sensors have been widely studied and applied.The preparation of new electrode modified materials to improve the analytical performance of the sensors is an important research direction in the field of electrochemistry.Graphene has the properties of high specific surface area,excellent mechanical strength and stability,excellent optoelectronic properties,good thermal conductivity,as well as excellent electronic conductivity.Thus,it is widely used in the research fields of biosensor,fuel cell,catalyst supports,energy storage and electronic devices.Graphene-based nanomaterials,such as heteroatom-doped graphene and graphene-based nanocomposites,further improve the performance of graphene.Among them,the introduction of heteroatoms in graphene will cause the change of charge transport,band gap,thermal stability,optical and magnetic properties,increase the active sites and improve the catalytic performance of graphene;taking the advantages of both nanomaterials and graphene,graphene-based nanocomposites have diverse structures and types,higher electrical conductivity and catalytic activity.The electrochemical sensor utilizing graphene-based nanomaterials is expected to improve its signal response and analytical performance.On the other hand,metal-organic framework materials?MOFs?are widely used in gas storage and separation,drug delivery,catalysis,and chemical sensing and other fields due to their ultra-high porosity and specific surface area.However,MOFs have the disadvantages of poor chemical stability and conductivity,which limits their application in electrochemical sensors.Thus,we prepared MOFs composites by combining MOFs with various functional materials to improve the stability and conductivity of MOFs.In addition,the MOFs composites combine the advantages of both,physical and chemical properties such as catalytic properties are significantly enhanced.The application of MOFs composites to electrochemical sensors can significantly improve the sensitivity and selectivity of sensors.In this paper,utilizing graphene-based nanomaterials and MOFs composites,we constructed electrochemical sensors for the detection of H₂O₂ and thrombin.Works of this paper are as follows:1.Using 5-amino-2-mercapto-1,3,4-thiadiazole as N and S sources,N and S heteroatoms co-doped reduced graphene oxide?NS-rGO?was produced via a simple one-step thermal annealing procedure.The co-doping of N and S atoms could offer more effective surface area and active sites,increase the charge-carrier concentration,and enhance the conductivity of carbon matrix.NS-rGO demonstrated superior electrocatalytic performance to H₂O₂ reduction,and it can be used for the construction of enzyme-free H₂O₂ electrochemical sensor.The sensor has high sensitivity,superb selectivity,good reproducibility,and long-term stability in the determination of H₂O₂,which proves that NS-rGO has enormous application potential to replace noble metal materials in the construction of electrochemical sensor.2.Through the hydrothermal self-assembly method,graphene quantum dots?GQDs?and graphene oxide?GO?were successfully compounded to obtain graphene quantum dots/graphene?GQD/G?.GQD/G were thermal annealed with thiourea to acquire N and S co-doped graphene quantum dot/graphene?NS-GQD/G?nanosheets.NS-GQD/G has good electrical conductivity,high peroxidase-like activity,and enriched active sites,and has good electrocatalytic performance for the reduction of H₂O₂.NS-GQD/G was utilized as sensing platform to construct a sensitive and selective H₂O₂ electrochemical sensor.The sensor can be used to detect H₂O₂ in human serum and H₂O₂ that released from live cells,and it is expected to be used in physiological and pathological research.3.AuPt nanoparticles?AuPtNPs?were successfully grown on ZIF-8-rGO bi-support via a wet-chemical method to obtain AuPt/ZIF-8-rGO.Due to the ultra-small and well-dispersed AuPtNPs,the synergistic effect of Au and Pt bi-metals,the strong metal-support interaction between AuPtNPs and ZIF-8-rGO bi-support,and the sandwich-like structure comprising porous ZIF-8 and loosely packed rGO nanosheets,the AuPt/ZIF-8-rGO shows superb electrocatalytic activity to H₂O₂.The electrochemical sensor based on AuPt/ZIF-8-rGO exhibits high sensitivity and selectivity to the detection of H₂O₂,and it can be employed for the practical tracing of H₂O₂ in the human serum samples with desirable property.4.Using Au nanoparticles?AuNPs?-functionalized covalent organic frameworks?Au-COFs?as conductive substrates,AuNPs functionalized ZIF-8 which encapsulated with NiPd nanoparticles?Au@ZIF-8?NiPd??as nanocarriers,a sensitive sandwich-type electrochemical aptamer sensor was constructed for the detection of thrombin.Au-COFs has the characteristics of high specific area,super electroconductivity,and uniform distributed AuNPs,Au@ZIF-8?NiPd?owns porous structure,large specific surface area,excellent catalytic performance,and high peroxidase catalytic activity.With the synergetic effect of nanocarriers Au@ZIF-8?NiPd?and electrode matrix Au-COFs,the aptasensor exhibited high sensitivity and selectivity,and it can sense thrombin in human serum.