Diffusion-Mechanical Energy Conversion Behavior Of Graphene Film

With limiting amount of fossil fuels and increasing of environmental pollution,we are facing the grand challenge of existing energy conversion mode and that is represented by fossil fuel's chemical energy into mechanical energy.In order to solve this problem,a green and sustainable energy conversion method is urgently needed.The microfludic devices is different from other energy conversion such as wind energy because it can realize the efficient utilization of energy without outside buildings.On the other hand,graphene advantages of special physical and chemical properties,is considered an ideal materials for microfludic devices and received great attention.Therefore,the porous graphene film with unique selective wettability(hydrophobic and ethanol-wet)was prepared by coating and consequent thermal treatment and graphene oxide(GO)was used as a raw material.Due to one-way diffusion of organic molecules in the graphene sheets into water,graphene film was pushed to fixed-axis rotation or linear motion on the water,leading to the conversion from diffusion energy into mechanical energy.In this paper,the factors influencing energy conversion efficiency were investigated and a physical-mathematical model of diffusion-mechanical conversion was established.Specific research work includes the following three aspects:The influence of physical properties and configuration parameters of graphene film was discussed.Based on the research of different materials with different wettability for water and ethanol,the unique selective wettability(hydrophobic and ethanol-wet)was considered as the key factor of ethanol one-way diffusion.Then the influence of annealing temperatures was discussed and proved the hydrophobic of graphene film was not a control factor for rotation speed.Based on the research of configuration parameters such as shape,area,aspect ratio and thickness found that the movement of graphene driven by kinetic moment and resistance moment in opposite directions at the same time.They increased with increase of lever arm and the resistance moment was dramatically increased.The influence of “fuel” solvents and diffusion media on the conversion efficiency was discuss.In order to realize movement of graphene film and energy conversion,“fuel” solvents must not only be satisfied with selective wettability of graphene film,but also soluble in the water.On this basis,the “fuel” solvent concentration gradient between film inside and outsideand the density of the solvent also influenced the movement of graphene film.And the rotation speed increased with the increase of concentration difference,and the decrease of the "fuel" solvent density.Further on this basis,linear motion and continuous rotation of graphene film can be realized through the experiment design and experiment equipment improvement.Based on the research of different conversion efficiency factor,the role of gas in film movement has been prove and it kept the certain pressure difference of the solvent inside film and ensure "fuel" solvent can continue to diffusion.Then a gas-liquid-solid three phase model with diffusion-mechanical energy conversion was established further.In order to explained the rotation direction of the graphene film,the hypothesis was formulated that the rotation was triggered by asymmetric torque derived from different ethanol concentration.Finally,formulas of graphene film speed were given by introducing ORR khodorkovsky formula and two-film theory,and the qualitative relations between rotation speed and influence factors in practical experiments was illustrated through formulas.