Fabrication And Application Of Flexible Fiber-shaped Photoelectrochemical Sensors Based On Carbon Nanomaterials

Flexible fiber-shaped carbon nanomaterials sensors have the the promising use for monitoring personal healthcare and environment safety due to its advantages of lightweight,high conductibility,prominent flexibility and outstanding stability.However,the sensitivity and selectivity of flexible fiber-shaped carbon-based sensors is still poor,which limits application in some areas.Photoelectrochemical sensing as a quite promising analytical technique has gained more attention due to its advantages of excellent sensitivity,rapid test,low background signal and simple instrumentation.In this thesis,the fiber-shaped carbon nanomaterials and photoelectrochemical sensing technology have been employed to fabricate fiber-shaped photoelectrochemical sensors including photoelectrochemical urea sensor based on molecularly imprinted graphene（G）fiber,coaxial fiber-shaped photoelectrochemical methane sensor based on G and carbon nanotube（CNT）and Ag nanofiber-enhanced coaxial fiber-shaped carbon-based photoelectrochemical methane sensor.The main work could be summarized as follows:（1）The molecular imprinting and photoelectrochemical sensing strategies were used for developing a photoelectrochemical urea biosensor based on flexible G fiber.The remarkable combined features of the resulting sensor with high surface roughness,good transmittance and molecular recognition could contribute to convenient light absorption,good adsorption capacity and selective detection.The obtained results indicated that the sensor exhibited good flexibility,stability,high sensitivity and selectivity in urea detection,with a linear range from 0.01 to 1500μM and a limit of detection of 1 n M.The practical application of the sensor was also realized in the selective detection of urea in real samples.（2）A coaxial fiber-shaped G@PVA@GCT photoelectrochemical methane sensor was successfully designed and fabricated by employing G fiber,polyvinyl alcohol（PVA）-H₃PO₄ gel and G-CNT-TiO₂（GCT）as the inner electrode,in-between electrolyte and outer electrode,respectively.The electrolyte interlayer was thin yet continuous and tightly merged with both the outer electrode and inner electrode without any noticeable gaps and holes.The resulting sensor with mixed-dimensional hybrids could contribute to methane adsorption capacity and photoelectric response.The obtained results indicated that the sensor with 10μm PVA layer in thickness,100μm GCT electrode layer in thickness and 30%CNT amount exhibited high sensitivity and selectivity in methane detection,with a linear range from 0.05%to 0.47%and a detection limit of 0.04%.（3）A coaxial fiber-shaped CNT@PVA@GAT photoelectrochemical methane sensor was successfully designed and fabricated by employing CNT fiber and G-Ag nanofiber-TiO₂（GAT）as the inner and outer electrodes,and PVA-H₃PO₄ as middle electrolyte layer.The Ag nanofiber in GAT layer and a tight contact between electrodes and electrolyte interlayer significantly promoted the facile transport of electrons and ions.The obtained results indicated that the sensor with 5μm PVA layer in thickness,95μm GAT electrode layer in thickness and 35%Ag nanofiber amount exhibited high sensitivity and selectivity in methane detection,with a linear range from 0.05%to 0.38%and a detection limit of 0.03%.