| Collecting dynamic environmental data of ocean via marine wireless sensors is one of the key measures to promote the sustainable and healthy development of marine industry.To promote miniaturization of marine wireless sensors,it is necessary to propose solutions for integration of power supply and sensing parts.Based on Prussian blue(PB)crystals that can store and transport electrons and sodium ions,new devices with integrated power supply and sensing functions can be developed.In order to achieve this goal,we need to tackle key problems including preparation of PB films which are suitable for marine environment,establishing relationships among microstructure of the films,mechanical properties,charge transport properties,and environmental parameters.This dissertation focuses on the preparation of PB films and their preliminary applications in power supply and sensing.The main research results are as follows.1.Oriented deposition of PB films and the mechanism.On the basis of crystal growth principles,PB films with different orientation structures were fabricated by controlling the nucleation rate and density and crystal growth direction.Cubic films are formed through equiaxed growing of grains with{200}crystal class exposed.This is a result of slow nucleation,deficient nuclei,and isotropically attached atoms causing by inhibitor molecules.When nuclei grow rapidly and abundantly,the grains grow along the[111]directions preferentially following the rational exponential law.The surface of grain is encapsulated by the slowest growing crystal facet,forming prismatic films.2.The structure-function relationship among the microstructure of PB films and their anti-pressing properties and corrosion resistance.Considering the harsh environment and the influence caused by seawater and complex external forces,we investigated mechanical properties and corrosion resistance of the PB films with different orientation structures.After repeated bending tests,the prismatic films maintain their initial structures with excellent flexibility.The zigzag-shaped surfaces and the parallel arrays of the prismatic films can absorb energy effectively,ensuring the prismatic film to withstand friction and pressing experiments.The prismatic films transport ions and electrons stably under repeated mechanical pressing.The parallel grains of the prismatic film reduce the charge transfer resistance and enhance the ion conductivity.After being immersed in seawater,PB films can resist corrosion of seawater.The microstructures and crystal structures of the films cannot be changed by seawater.3.Evaluation of electricity supply performance of PB films.The prismatic PB films can store and transfer mixed ions and electrons,however,suffer deterioration of performance during power supply.According to the microstructural and electrochemical analyses,the degradation of the performance of the prismatic PB films is caused by corrosion of OH~-and polarization of hindered charge transfer.A protective coating is constructed by coordination between polydopamine molecules and iron nodes in PB crystals.The coatings protect the PB films from etching by the OH~-ions without disturbing transportation of sodium ions.Carbon nanotubes are embedded into the films to improve their electron conductivity.The impedance of the films is reduced to～12Ω.After modifications,the obtained films exhibit good stability during power supply.4.Evaluation of sensing properties of the PB films.According to the storage property of mixed ions and electrons of PB crystals,the modified prismatic PB films were assembled with active alloys to form prototype marine sensing device.The output voltages of the prototype devices positively correlate to seawater salinity,temperature,and concentration of the dissolved oxygen,in consistent with the analytical results from the Nernst equation.The measurement ranges are 1.0～4.0 wt.%,-10～30 ~oC and 3～9mg/L for the salinity,temperature and concentration of the dissolved oxygen,respectively.5.Fabrication of porotype devices and their preliminary applications.Based on the flexibility,the prismatic PB film and Al/Mg alloys were assembled onto manta fish models to construct power supply devices.The prototype device exhibits stable dual-mode power supply characteristics in the simulated seawater under fluctuating,driving the propeller and illuminating the LEDs successfully.Combining the device with a multimeter,seawater salinity is measured on the basis of the quantitative relationship between voltage and salinity.These evidences preliminary prove the feasibility of integrated power supply and sensing,providing an initial basis for the development of new marine wireless sensors. |
PDF Full Text Request