Study On The Performance And Power-generation Mechanism Of Composite Structure TiO₂ Nanowires Self- Powered Devices

To solve the energy crisis and environmental pollution caused by the use of batteries in wearable devices,some scholars have proposed to use self-powered devices to replace batteries.Fluid-induced self-powered devices based on streaming potential have become a very potential alternative to batteries,because of low raw material costs and simple device preparation method.However,the fluid-induced self-powered devices based on streaming potential generally have the disadvantages of lower output power and slower response.In this thesis,a sequential electrophoretic deposition method was proposed to fabricate the composite structure TiO₂nanowires（TiO2 NWs）self-powered devices and the output power can be enhanced to 455.40μW eventually.The electrical and mechanical properties of the composite self-powered devices fabricated by different materials were systematically studied,and the mechanism of different composite self-powered devices was analyzed.First,anatase-type TiO₂ NWs were synthesized by the hydrothermal method,and then the TiO2 NWs self-powered devices were fabricated by electrophoretic deposition.The maximum output power of the device at room temperature was 1.88μW,and the response time to water was less than 0.1 s.As the temperature of the TiO₂ NWs device increases,the maximum values of the open-circuit voltage and short-circuit current gradually increase.The output power of the TiO₂ NWs device at 60℃was 14.39μW,which is over 5 times higher than that at room temperature.However,the TiO₂ NWs devices were easily damaged during the test.The silver nanowires（Ag NWs）-TiO₂ NWs composite self-powered devices were fabricated by the sequential electrophoretic deposition method to improve the output power.Because the Zeta potential of Ag NWs is negative,and the sintered Ag NWs has excellent electrical conductivity,the maximum output power of the Ag NWs-TiO₂ NWs composite device can reach 15.61μW,which is 5.41 times that of the TiO2 NWs device.Carbon nanoparticles（CNPs）,which also have excellent electrical conductivity and negative Zeta potential,are selected to composite with TiO₂ NWs.The output power of the CNPs-TiO2 NWs composite device can reach 71.92μW,which is 24.73 times that of the TiO2 NWs device.The response time of the CNPs-TiO₂ NWs composite device to deionized water,ethanol,acetone,and methanol all reached the millisecond level,which is two orders of magnitude shorter than carbon materials based self-powered devices.The CNPs-TiO₂ NWs composite device also showed high sensitivity,long service life,and high mechanical strength.Graphene（G）and TiO₂ NWs were composited by sequential electrophoretic deposition to prepare the G-TiO₂ NWs composite device.The maximum output power generated by this composite device was 171.56μW.By assembling multi-layer G-TiO2 NWs composite devices,the output power can be raised 455.40μW,which is 242.32 times of TiO₂ NWs devices.