Preparation And Electrochemical Sensing Of Novel Metal Nanoparticles/graphene-based Carbon Nanocomposites

Due to the special physical and chemical properties of carbon nanomaterials,it has attracted the attention of scientists.In recent years,carbon nanomaterials and their composites have shown bright prospects in almost all materials science fields.In particular,graphene nanocomposites have many excellent properties.In this paper,several new carbon nanomaterials and their composites have been prepared,and their electrochemical biosensing properties and applications are studied.Chapter 1:The definition,development,classification and research progress of carbon nanomaterials and their composites in the field of electrochemical sensing are briefly described.Chapter 2:A controllable flower-like Pt-graphene oxide（PtNF-GO）architecture was synthesized through layer-bylayer electrostatic self-assembly.Hexadecyltrimethylammonium chloride（CTAC）micelles were employed as the template and Pt nanoflowers with different sizes were selectively synthesized by controlling the dissolved K₂PtCl₄ precursor and CTAC amounts in the reaction system.The prepared PtNF-GO was applied for DNA damage biomarker 8-hydroxy-2’-deoxyguanosine（8-OHdG）biosensing research.With the distinctive flower-like morphology of PtNFs and high electrical conductivity of GO,the PtNF-GO architecture shows excellent electrochemical biosensing performance towards the oxidation of8-OHdG.A very low detection limit of 0.025 nM is obtained.Moreover,the fabricated PtNF-GO was used for the detection of 8-OHdG generated from the damaged DNA sample,which can be used to evaluate and confirm the mechanism of DNA damage,and it is of great importance in gene diagnosis,clinical and life sciences.Chapter 3:The development of high-performance noble metal-free electrochemical catalyst for effective water splitting is a key factor to achieve low-cost and sustainable renewable energy production.Herein,for the first time,highly dispersed cobalt nanoparticles decorated uniform nitrogen doped graphene（CoNPs-N-GR）was design synthesized.In the preparation procedure,graphene oxide（GO）was employed as supporting material,polydopamine as nitrogen source,location reagent as well as connecting agent for uploading cobalt metal ion,and then cobalt metal-organic frameworks（ZIF-67）in situ grew on GO.During the calcining process,GO reduction,nitrogen doping and cobalt nanoparticles forming were finished in one step.Scanning electron microscopy（SEM）images,transmission electron microscopy（TEM）,energy-dispersive X-ray（EDS）,X-ray photoelectron spectrometer（XPS）and X-ray diffraction（XRD）were applied to characterize the as-prepared CoNPs-N-GR.Moreover,owing to the presence of dopamine,high dispersed cobalt nanoparticles were obtained,leading to high electrocatalytic activity of CoNPs-N-GR for both hydrogen evolution reaction（HER）and oxygen evolution reaction（OER）in alkaline media.HER reaches 10 mA cm^-2 at the over-potential of 0.453 V with a Tafel slope of 67 mV dec^-1.OER reaches 10 mA cm^-2 at the over-potential of 1.63 V with a Tafel slope of 65 mV dec^-1.And the as-prepared CoNPs-N-GR shows excellent durability in the long-term stability for HER and OER.