Synthesis Of Cu₂O-MWCNTs Nanocomposites For Applications In Supercapacitors And Biosensors

Nanostructured copper-based oxides are promising electrode materials for applications in supercapacitor and biosensors due to the advantages of low cosst,environment friendliness and excellent electrochemical performance.However,the poor electrical conductivity of nanostructured copper-based oxides hinders its further applications in high-performance supercapacitors and biosensors.In this dissertation,the cuprous oxide-carbon nanotubes nanocomposites were prepared by one-step ionic liquid assisted sputtering deposition method,which shows excellent performances in the field of supercapacitor and biosensor.The main works can be summarized as follows:Firstly,cuprous oxide-carbon nanotube nanocomposites?Cu₂O-MWCNTs?were successfully prepared by one-step ionic liquid assisted sputtering deposition method.This physical synthesis method is different from the traditional chemical synthesis methods to prepare metal nanoparticles.During the preparation process,no stabilizers such as surfactants and polymers are introduced,and there is no need for surface treatment or modification of carbon nanotubes.The method is simple and efficient,and the optimized synthesis conditions are obtained that is 1-butyl-3-methylimidazolium tetrafluoroborate?BmimBF₄?ionic liquid is used and the stirring temperature is set to be250°C.Small-sized?⁹ nm?,uniform and well-crystallized Cu₂O nanoparticles are obtained which are uniformly loaded on carbon nanotubes with a large loading percent.Then,the synthesized Cu₂O-MWCNTs nanocomposites were utilized as positive electrode materials of supercapacitors with excellent electrochemical performances,which were further improved by introduction of oxygen vacancies induced by NaBH₄reduction treatment.The three-electrode test results showed that after the reduction treatment,the r-Cu₂O-MWCNTs exhibited a greatly improved specific capacitance of790 F/g at a scan rate of 5 mV/s and high cycle stability?the specific capacitance remains about 92.5%of the initial capacitance after 20 000 charge/discharge cycles at a current density of 10 A/g?.The electrochemical performances of our obtained r-Cu₂O/MWCNTs nanocomposite are superior to other reported copper-based positive electrode materials.The asymmetric supercapacitor is assembled utilizing r-Cu₂O/MWCNTs and activated carbon as positive and negative electrode materials,respectively.The asymmetric capacitor exhibits an energy density of 64.19 Wh/kg at a power density of 825.27 W/kg and an energy density of 19.52 Wh/kg at a power density of 10.04 kW/kg,which can be used to drive the commercial LEDs practically.Lastly,the prepared Cu₂O-MWCNTs nanocomposites also exhibited excellent enzyme-free glucose detection performances.The time-current test results showed that the best working voltage was 0.55 V,and high enzyme-free glucose detection sensitivity(¹0.296 mA·mM^-1·cm^-2)and low detection limit?0.1?M?were obtained.Moreover,the Cu₂O-MWCNTs nanocomposite electrode shows high long-term stability that is the current response of the electrode remains 95%after 19 days of testing.It also exhibits strong anti-interference over others in blood such as ascorbic acid,sodium chloride,uric acid,lactose,urea etc.It is promising in practical application of enzyme-free glucose detection electrochemical sensors.