Study On Based On Biomass-based Carbon Nanocomposites Electrochemical Sensors

Biomass materials are important precursors and the only carbon source in renewableresources.It is a research hotspot to develop a controllable structure high-performance carbonaceous material by using biomass based materials as raw materials.Natural materials are excellent to synthese biomass carbon materials,which usually have unique functional structures through carbonization and activation.By using it as a template and further introducing inorganic or organic guest materials,composite materials with unique and complex multi-level morphological structures can be obtained.The nanocomposites show the advantages including large specific surface area,high conductivity,fast electron transfer capability and good biocompatibility,which can be used for electrode modification to improve interface morphology and structure with electrode performance enhanced.In this thesis,various biomass-based carbon nanocomposite were applied to detect small molecules with electrochemically active and fix the redox proteins（enzymes）.This thesis mainly includes the following contents:（1）A sensitive electrochemical method was proposed for the determination of luteolinbased on platinum（Pt）nanoparticles decorating a biomass porous carbon（BPC）composite-modified carbon ionic liquid electrode（CILE）.For Pt-BPC/CILE,a pair of well-defined redox peaks of luteolin was appeared with enhanced peak currents and the positive movement of peak potentials,proving the electrocatalytic activity of the Pt-BPC nanocomposite for redox reaction.The results could be ascribed to the porous structure of BPC,the catalytic activity of Pt nanoparticles and their synergistic effects.Electrochemical parameters were calculated via cyclic voltammetry and differential pulse voltammetry.The results showed that the oxidation peak currents increased linearly with the concentration of luteolin in the range from 0.008 to 100.0μmol/L,with the detection limit of 2.6 nmol/L.The analytical performance of the sensor was checked by the detection of luteolin contents in Duyiwei capsule drug sample.（2）The banana skin was used as the raw material to prepare banana skin orginatedbiomass porous carbon（BPBC）through carbonization and alkali treatment,which was mixed with multi-walled carbon nanotubes（MWCNT）at an optimized ratio to get a MWCNT-BPBC composite.A BPBC-MWNCT modified electrode was prepared by using glassy carbon electrode（GCE）as the base electrode and applied to the electrochemical detection of baicalin.Then cyclic voltammetry and differential pulse voltammetry were used to study the electrochemical response of baicalin and to calculate related electrochemical parameters.The linear ranges were from 0.004 to1.0μmol/L and from 2.0 to 100.0μmol/L with the detection limit of 1.33 nmol/L.BPBC-MWNCT/GCE was applied to the quantitative analysis of baicalin content in Shuanghuanglian oral solution with satisfactory results.（3）The fungus was used as the raw material to prepared biomass porous carbon（FBPC）,which was further decorated by hydrothermal method to prepare MnO₂@FBPC composite.Then MnO₂@FBPC was modified on the surface of carbon ionic liquid electrode（CILE）to obtain a working electrode（MnO₂@FBPC/CILE）for the sensitive voltammetric determination of rutin.Electrochemical response of rutin was studied via cyclic voltammetry and differential pulse voltammetry.Under the optimal conditions,the linear range for rutin analysis was from 0.008 to700.0μmol/L with the detection limit as 2.67 nmol/L.This fabricated MnO₂@FBPC/CILE wasapplied to direct detection of rutin concentration in drug and human urine samples.（4）The walnut shells were used as the raw material to prepared biomass porous carbon（WSBPC）.Nafion/HRP/Au/WSBPC/CILE was prepared by layer-by-layer coating and deposition method.UV and FT-IR results spectroscopy proved that HRP maintained its biological structure.The direct electrochemical behavior of Nafion/HRP/Au/WSBPC/CILE was achieved in PBS（pH5.0）as the supporting electrolyte solution.The electrocatalytic performance of Nafion/HRP/Au/WSBPC/CILE on trichloroacetic acid（TCA）and potassium bromate（KBrO₃）were studied with the apparent Michaelis-Menten constant(K_M^app)calculated as 616.43 mmol/L and 0.36 mmol/L.The linear range was from 10.0 to 1000.0 mmol/L for TCA and from 0.1 to 1.1mmol/L for KBrO₃ with the detection limit as 3.33 mmol/L and 0.03 mmol/L,respectively.