Application Of Doped Hollow Carbon Nanoparticles In Cathode Of Zinc Air Battery And Anode Of Enzyme Biofuel Cell

With the shortage of traditional energy sources and environmental pollution,our society has shifted from fossil fuel economy to clean energy economy,and we are actively studying the collection,conversion and storage of sustainable energy.Compared with the batteries in the traditional sense,zinc air batteries and biofuel cells have the advantages such as wide sources of raw materials,low cost,high energy conversion and free-pollution.In this paper,the highly active B,N-codoped hollow carbon nanospheres(BNCSs)were used as cathode(gas diffusion electrode)catalysts to prepare and optimize gas diffusion electrodes for zinc air batteries,then they were assembled into zinc air battery for electrochemical testing.Highly active BNCSs as anode carriers were prepared and optimized for the anodes of enzyme biofuel cells,then they were assembled into enzyme biofuel cell for electrochemical testing.The main points of this dissertation are described as follows:Carbon paper was used as the current collector,the gas diffusion layer was composed of acetylene black and polytetrafluoroethylene emulsion(PTFE),and the catalytic layer was composed of activated carbon-based BNCSs and PTFE.The hydrophobic concentration and time of the collector were optimized.The ratio of acetylene black to PTFE in the gas diffusion layer and the loading of acetylene black were optimized.The proportion of BNCSs,activated carbon and PTFE,and the loading of BNCSs were optimized.The results showed that the current collector was hydrophobically treated in 10 wt.%PTFE emulsion for 5 min,the mass ratio of acetylene black/60 wt.%PTFE in the gas diffusion layer was 6:4(the loading of the acetylene black was 0.8 mg/cm~2)and the mass ratio of activated carbon/BNCSs/20 wt.%PTFE in the catalyst layer was 2:2:3(the loading of BNCSs was 1.0 mg/cm~2).A rectangular zinc air secondary battery device composed of polymethylmethacrylate was designed and manufactured.It possessed excellent sealing performance,easy replacement of electrolyte and zinc anode,convenient to clean,and effortless to observe the reaction inside.The properties of B-doped hollow carbon nanospheres(BHCSs),N-doped hollow carbon nanospheres(NHCSs),BNCSs and commercial Pt/C assembled zinc air batteries were compared.Using the bifunctional electrocatalyst BNCSs,zinc air primary and secondary batteries operating in air atmosphere were fabricated.The primary zinc air batteries on the basis of the BNCSs demonstrated an open circuit voltage of 1.421 V,a specific capacity of670 mAh/gZn at a current density of 5 mA/cm~2 and a peak power density of 96 mW/cm~2.Secondary zinc air batteries could be cycled for 350 cycles at 10 mA/cm~2,still retaining excellent stability.Results show that the inexpensive BNCSs are very applicable to energy conversion devices.Using the prepared BNCSs as carriers to immobilize glucose oxidase(GOD)through simple physical adsorption,thus biofuel cell anode GOD/BNCSs/GC was prepared.Then the loading of BNCSs,loading of GOD and glucose concentration were optimized.When the BNCSs concentration was 0.5 mg/mL,GOD concentration was 5 mg/mL,and glucose concentration was 3mM,the current density reached the maximum.It was worth noting that the electrode exhibited almost no change in electrocatalytic activity after being stored at 4?for seven days,indicating good stability of the prepared bioanode GOD/BNCSs/GC.The EBFC with GOD/BNCSs/GC as anode and gas diffusion electrode as cathode was constructed.The open circuit voltage and short circuit current were 0.68 V and 0.63 mA/cm~2,and the maximum power density was 52.5?W/cm~2 at 0.22 V.