Mechanism And Performance Study Of Photocatalytic Self-cleaning Triboelectric Nanogenerators

Triboelectric nanogenerators（TENGs）is a new technology that converts environmental mechanical energy into electric energy based on friction electrification and electrostatic induction coupling.In the past decade,friction nano-generators have attracted much attention because of their applications in many fields,including medical,electronics,sensors,artificial intelligence and other fields.It has the advantages of high-power conversion efficiency,simple structure,low cost,durability,strong expansibility,and can extract energy from low-frequency irregular mechanical energy.It has been proved that all kinds of ocean energy,wind energy,human kinetic energy and other mechanical energy can be converted into electrical energy.Compared with traditional generators,friction nano-generators can collect wireless energy and transmit wireless energy in harsh environments or high noise.Therefore,it is considered to be a promising energy collection and renewable resource.Especially in recent years,with the development of digital medicine,TENG has shown great potential in the field of wearable and electronic skin,but wearable devices and electronic skin will inevitably be contaminated in daily use,which will not only affect the output performance of the device but also reduce the comfort of wearability.Therefore,the combination of self-cleaning surface and friction material can provide the possibility to solve the problem of device contamination.Photocatalysis can degrade macromolecular organic pollutants into small molecular carbon dioxide（CO₂）and water（H₂O）under light excitation,which has attracted the attention of researchers because of its environmental friendliness,high selectivity and reusability.On the other hand,in order to adapt to more application scenarios,TENG needs to have the ability of shape adaptation,especially wearable devices.On this basis,a friction nano-generator with photocatalytic self-cleaning and shape self-adaptive function was designed by combining Ti O₂photocatalyst with the spraying process.The specific research work is as follows:（1）Ti O₂suspension has both liquid phase and solid phase.Therefore,through the cyclic operation of spraying and pre-drying,Ti O₂nanoparticles can be deposited on irregular substrates and used as friction layers,which provides a feasible operation for the fabrication of profiled TENG.Based on this,we first simply designed a Ti O₂-based friction nano-generator with vertical contact separation and selected PTFE as another friction layer.The output performance of TENG is optimized by adjusting suspension concentration and spray volume.And under the condition of light,the performance of the device can be restored by photocatalytic self-cleaning.On the other hand,TENG prepared by spraying Ti O₂suspension is also universal to substrates with different shapes.In a word,TENG based on Ti O₂photocatalyst not only has good output performance but also has photocatalytic self-cleaning and shape self-adaptability,which can further expand the application of TENG.（2）Based on the experiment in the previous chapter,we have made further improvements to the materials.Polyvinyl alcohol（PVA）has excellent film-forming,adhesion and mechanical stability.The shape adaptive and photocatalytic self-cleaning film（SAP）adhering to the substrate can be obtained by spraying the mixed solution of Ti O₂nanoparticles and PVA and drying repeatedly.SAP film has flexibility and tensile properties and has excellent output performance as a friction layer.At the same time,under the irradiation of sunlight,SAP film can degrade the pollutants attached to its surface and restore its original output performance to a certain extent.At the same time,SAP films perfectly adapted to the substrate shape,such as pyrathe mid and hemispherical films,can be obtained by the simple spraying method,which is a more complex shape of TENG.