The Study On CO₂ Ionization Driven By Triboelectric Nanogenerator And Its Application In CO₂ Redcution

Carbon dioxide is the main gas causing the“greenhouse effect”which seriously threatens the sustainable development of human beings.Therefore,how to efficiently convert atmospheric CO₂ into high value-added fuels and chemicals has become a hot research topic.Electron transfer between semiconductor materials and CO₂ molecules is the key step in the transformation and utilization of CO₂.Since the lowest unoccupied molecular orbital energy level of CO₂ is much larger than the conduction band energy level of common semiconductors,most of the electrons in semiconductor conduction bands are difficult to transfer to CO₂ molecules.It leads to the low activity of CO₂ conversion.In this thesis,a large number of high-energy electrons activated CO₂ derived from the gas discharge driven by triboelectric nanogenerators?TENG?is used to form CO₂^-active species,which effectively overcomes the electron transfer barrier between semiconductor materials and CO₂ molecules.The electron transfer is also accelerated,resulting in promoting the electron driven CO₂ reduction.Based on the above design,a new and efficient CO₂ catalytic system at room temperature is proposed.The research content of this thesis mainly includes the following two parts:1.Research on gas discharge characteristics driven by triboelectric nanogenerators:The gas discharge device of the needle-plate structure is combined with the TENG.Utilizing the high voltage characteristics of TENG,the process of electrons activated CO₂ to form CO₂^-without additional power at room temperature is realized,and the effective detection of CO₂ is further realized.The maximum discharge distance(d_max)of different gases is studied.It is found that it has a wider operating range under the negative voltage gas discharge,and the d_max values of CO₂,O₂,air and N₂ are 0.11 mm,0.28 mm,0.45 mm and 0.55mm,respectively.The dependence of the discharge characteristics of N₂ and CO₂ on the discharge distance?d?is investigated when the negative voltage gas was ionized.It is proved that d not only affects the peak value of the discharge current?0-20.1?A?,but also changes the frequency of the single-cycle discharge pulse?0-34 Hz?.The application of gas discharge in CO₂ gas sensitive detection is realized through utilizing the gas discharge characteristics driven by the TENG.2.The application of gas discharge driven by triboelectric nanogenerators in CO₂ reduction:Through the negative voltage mode of the gas discharge driven by TENG,CO₂ activation method with a large number of electron active centers is designed,and combined with the catalyst to achieve efficient CO₂conversion at room temperature.The catalyst suitable for this system is screened by controlling the reaction conditions.Ga₂O₃ shows much higher catalytic activity of 78 ppm/h,which is far larger than that of common semiconductor catalysts.By investigating the effect of discharge characteristics on the catalytic activity of Ga₂O₃,it is shown that when the d is 0.15 mm,the single-cycle discharge pulse frequency is 3Hz,the discharge current peak value is 69.4?A,and the single-cycle discharge charge is 300 nC,and the catalytic effect is the best at this time.Through the characterization and stability test of the catalyst,it is proved that the oxygen vacancies are continuously cycled,and the activity of the Ga₂O₃ catalyst remains stable for a long time.We combine the gas discharge device of the needle-plate structure with the TENG in this thesis.Using the high voltage generated by frictional electrification and electrostatic induction coupling,the gas is ionized to form a plasma including a large amount of high-energy electrons.It provides a simple,safe,and economical method for the generation of plasmas containing large number of high-energy electrons.At the same time,through gas discharge driven by TENG,the efficient conversion and detection of CO₂ at room temperature is realized,which is of great significance for alleviating the greenhouse effect and protecting human health.