| Enzymatic biofele cell?EBFC?is a going green and environmental friendly generated electricity device,which can utilize the enzyme as the catalyst to convert the biomass energy to electric energy.Especially for that the EBFC have the tantalizing potential appilication value of supplying power for implanted devices due to utilizing the glucose and oxygen in vivo to generate the electricity and researches in this field have been the frontier research of the international bioelectrochemical study.Although the EBFC have the considerable application value,two problems of the low power density and the short lifespan are still existed at present.This may be due to the slow electrons transfer between the enzyme and the electrode and the biological attribute of enzyme which make it survived litter time in vitro.Therefore,this paper focused on the key problem of how to improve the electrons transfer between the enzyme catalysts and the supporting materials and carried out the studies on exploiting the novel carbon nanomaterials and the suitable immobilization methods which could realize the directly electron transfer based on glucose oxidase?GOx?.We explored the carbon nanomaterials from one-dimension to three-dimension and optimized their morphology and properties for obtaining the faster direct electron transfer.The main work contains five parts as the below:?1?Identified the influence of incubation pH on the direct electrochemical behaviors of the GOx modified electrode.Enzymatic incubation environment,such as pH,temperature,ion species,et al,can effect greatly on the enzymatic immobilization process and the enzymatic property after immobilized,especially for the pH.Therefore,this paper utilized the carbon paper?CP?to as the supporting material and utilized the electrostatic adsorption method to immobilize the GOx,and studied on the direct electrochemical property of the GOx modified electrode based on different incubation pH?7,5,4,3,2?.The experiment results show that the direct electrochemical property was becoming better and better with the decrease of the incubation pH,and the best direct electrocatalytic property appeared at,the incubation pH 3.The direct electron transfer constant ks was 1.68 s-1 and a EBFC consisted of the GOx modified electrode as the anode and the Pt sheet as the cathode was constructed.The maxmun current density was 0.220 mA·cm-2 and the maxmum power density was 0.064 mW·cm-2.All these results indicated that the incubation pH would influence greatly on the property of the enzyme modified electrode and siutble incubation pH might obtain good results.?2?Constructed a direct electrochemical system of GOx base on the carbon nanochips?CNCs?.Carbon nanochips is a new type graphite fibers which are obtained by calcining the common carbon fibers at 2300-3000 ? and have the excellent physical,chemical and mechanical property,these characteristics make them becoming the one candidate of the ideal enzymatic supporting materials.Therefore,a new direct electron transfer GOx modified electrode was succesfuly prepared based on the carbon nanochips in this paper and studied on its direct electrochemical properties.The results showed that the best incubation pH of GOx based on CNCs was 4 and the direct electron transfer constant k,was 6.02 s-1.A EBFC consisted of the GOx modified electrode as the anode and the Pt sheet as the cathode was constructed.The maxmum current density was 0.220 mA·cm-2 and the maxmum power density was 0.064 mW·cm-2.All these results indicated that the CNCs was a very good suppoting materials for GOx,and which would be extended to immobilize the other enzyme or redox protein.?3?Constructed a direct electrochemical system of GOx base on porous carbon materials of PCPx.Metal-organic framewors?MOFs?is also called porous coordination polymers?PCPs?which have excellent pore structure,and their main characteristics are the ultrahigh porosity and the superhigh interior specific surface area.Therefore,this paper synthesized a porpous coordination polymers Al-PCP material through the hydrothermal method and studied the influence of carbonization temperature on the property of the porous carbon materials PCPx?x represents the carbonization temperature,??.The results showed that the specific surface area of PCP1600o was the maxmum value of 2773.5 m2·g-1 and the pore volume was 1.885 m3·g-1.The best incubation pH of GOx based on PCP1600 was 4 and the direct electron transfer constant k,was 9.5 s-1.A EBFC consisted of the GOx modified electrode as the anode and the Pt sheet as the cathode was constructed.The maxmun current density was 4.4 mA·cm-2 and the maxmum power density was 0.55 mW·cm-2.These results indicated that the two-step carbonization method can protect the metal-organic structure to not be destroyed.The high temperature carbonized materials could well immobilize the GOx and displayed excellent electrochemical property.Importantly,it can extend to other MOFs for carbon materials in the application of fixing the enzymes or redox proteins.?4?Constructed a direct electrochemical system of GOx base on carbonized tubular materials of PPy1600.Polypyrrole?PPy?have the characteristics of the manageable nano morphology and the luxuriant carbon source,which make it to be one of the ideal candidates for porous carbon nanomaterials.Therefore,this paper synthsised a PPy with tubular strucuture through the soft-template method.The tubular PPy was then carbonized at 1600 ? and obtained a tubular carbon materials of PPy1600?1600 represents the carbonization temperature,??.A GOx modified electrode based on PPy 1600 was prepared by the methods of electrostatic adsorption and layer by layer and studied on the direct electrochemical behaviors.The research results showed that the best incubation pH of GOx based on PPy1600 was 5 and the direct electron transfer constant ks was 12.06 s-1.In addition,an EBFC composed with the GOx modified electrode as the anode and the Pt sheet as the cathode was prepared,the maxmun current density of the EBFC was 3.7 mA·cm-2,the open-circuit voltage was 0.69 V,the maxmum power density was 0.72 mW·cm-2.These results above indicated that PPy owned the stable structure at the high temperature and the carbonized tublar PPy1600 would be used to immobilize the other enzymes or redox proteins.?5?Constructed a direct electrochemical system of GOx base on carbonized three-dimensional Polyaniline?PANI?composites.PANI is applied extensively in the materials of coating,battery,wave-absorbing material,sensor and conductinve fiber due to its properties of conductivity,easy to synthsis and controllable morphology.In addition,it is also be widely studied on the porous carbon materials as for it contains abundant carbon source,and the amino group on the aniline monomers is very active and easy to react.This characteristic will make the aniline monomers easily to bind the inorganic material with the functional groups by covalent bond.And the mixture will be a new type of three-demensional composite through the oxidation polymerization.Therefore,this paper synthsised three new composites of PANI@CNTs,PANI@GO and CNTs-PANI-GO with three-demensional structure through the in-situ polymerization,respectively.Then,the three composites were carbonized at 1600 ? and the products were denoted as PANI1600@CNTs?PANI1600@GO and CNTs-PANI1600-GO,respectively.The carbonized PANI among the carbon nanomaterials could act as the "glue" which might connect the carbon nanomaterials together to construct a new three-dimensional carbon nano-composites.After that,three types of GOx modified electrode based on the three carbon composites were prepared and studied on their direct electronchemical behaviors.The results show that the best incubation pH of GOx based on the three composites all were 3 and the direct electron transfer constant were 12.08 S-1?17.13 s-1?21.05 s-1,respectively.In addition,three EBFCs composed with the GOx modified electrodes as the anode and the Pt sheet as the cathode were prepared,the maxmun current densities of the EBFCs were 3.7,6.2?8.2 mA·cm-2,the open-circuit voltages were 0.78?0.79?0.8 V,the maxmum power densities were 0.72?1.12?1.51 mW·cm-2.These results above indicated that the carbonized PANI would act as the binder among the inorganic materials to construct them into three-demensional carbon materials which will be helpful to immobilize the enzyme.These new composites will be applied extensively in the EBFC field. |
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