Research On Strengthening Formaldehyde Degradation And Carbon Dioxide Reduction By Rotating Disk Photocatalytic Fuel Cell

The rapid development of industrialization and cities has been accompanied by a series of environmental problems.Among them,indoor volatile organic compounds?VOCs?represented by formaldehyde?HCHO?and outdoor greenhouse gases represented by carbon dioxide?CO₂?have threatened people's life and health,and even affected the survival of mankind.Fortunately,the photocatalytic fuel cell?PFC?system based on photocatalytic technology can solve the environmental problems effectively,which utilize clean solar energy to simultaneously perform the degradation of organic gases by photoanode such as HCHO and reduction of CO₂ into sustainable fossil energy by cathode.However,the application of PFC system in these directions faces the problems of poor mass transfer of substrates,high recombination rate of photogenerated carriers and large CO₂ emission.To address above issues,a rotating disk PFC system was constructed in this paper,which strengthened the adsorption and mass transfer of the reaction substrate on catalyst surface through the thin liquid film formed by electrode rotation,and realized efficient pollutant treatment,fossil fuel production and energy recovery by improving the separation efficiency of photogenerated carriers.The main research work includes:?1?A rotating disk TiO₂/platinum electrode PFC system was constructed,and the adsorption and degradation efficiency of gaseous HCHO was improved by the liquid-film on electrode surface.The experimental results showed that,the adsorption efficiency of the rotating disk PFC system on gaseous HCHO was increased by 17.8 times?94%?compared with the traditional gas-phase degradation system,accordingly,the degradation efficiency for gaseous HCHO increased by 2.6 times?82%?.It was proved that the rotating disk PFC system was not insensitivity for humidity by the environmental humidity control experiment.The mechanism of photocatalytic degradation of gaseous HCHO was further elucidated by free radical capture experiment.In addition,the electrical performance and stability of the the rotating disk PFC system were studied.Based on the principle,a new type of liquid-film air purifier is designed,and a good experimental results were obtained.?2?The thin-film rotating disk PFC system was constructed,and the efficient reduction of CO₂ was realized by using thin-film to enhance the CO₂ gas mass transfer between the liquid phase and the catalyst surface.The experimental results showed that the CO₂concentration in electrolyte of thin-film PFC system can reach in saturated in similar amount of time(0.035 mmol L^-1),compared with that of the traditional bubbling system.The CO₂reduction efficiency of thin-film PFC reached 2.7 times of the traditional bubbling system(7.6?mol g^-11 h^-1),which mainly due to the existence of liquid film,as to strengthen the mass transfer efficiency of CO₂.Subsequently,the conclusion was verified by numerical calculation.?3?By introducing the waste gas?CO₂?generated by the anode degradation pollutants into cathode chamber,a CO₂ self-recycling PFC system was constructed,which can achieved efficient degradation of pollutants by enhancing the separation efficiency of photogenerated carriers.The system provided a solution to the problem of CO₂ emissions in the traditional sewage treatment process.The results showed that with the anode product was introduced into the cathode,the pollutant degradation efficiency of the self-recycling PFC system increased by 40.3%compared with that of the photocatalyst alone.Simultaneously,the electrical performance and gas chromatography analysis showed that the self-recycling PFC system could also output 28.5?W cm^-22 of electrical energy and 6.7 mol g^-11 h^-11 of gaseous C1 fuel.Isotope experiments showed that the carbon source in the chemical fuel produced by the self-recycling PFC system comes from the organic pollutants in anode chamber.In addition,the applicability of the system was verified by degradation experiments of different pollutant substrates.