| Electron transfer is one of the fundamental processes in bio-conversions and physico-chemical reactions.In the marine environment,electron transfer exists in photosynthesis of alga,respiration of marine organism,seawater battery technology and carbon dioxide reduction technology etc.The power of seawater batteries is closely associated with the flux of the electron transfer between solid and gas phases,however,is often restricted by factors such as solvation of gas molecules,energy barriers during electron transfer,and collision probability between solid electron donors and gas acceptors.This dissertation focuses on the limited electron transfer rates between solid electron donors and gas electron acceptors in marine environment,and proposes to disperse microporous nanoparticles in seawater to form activated porous seawater which can bridge the solid-gas electron transfer,therefore,the flux of electrons and the performance of related devices can be increased.The main results are as follows.1)Preparation of porous seawater and the mechanism.Microporous particles are dispersed in seawater to prepare the seawater based functional fluid—“porous seawater”.The properties of the dispersed system are studied.The porous seawater forming by Na Fe[Fe（CN）6]particles is found to show unique stability and rheological properties which are found to be caused by the defects on the surface of the Na Fe[Fe（CN）6]particles on the basis of DLVO theory and extended double layer theory.Electrostatic repulsion is maintained among colloidal particles because that the negative charge bringing by defects cannot be neutralized by the ions due to the similar number of the anions and cations in stern layer.2)Principle and methods for characterizations of electron transfer between porous seawater and solid electrode.Cyclic voltammetry and UV-vis spectroscopy are applicable for porous seawater by comparing the samples in solid state,liquid state,and seawater state.The electron transfer between solid electrode and porous seawater can be measured by cyclic voltammetry.The change of coordination environment in colloidal particles can be reflected by UV-Vis spectra of porous seawater.In-situ electrochemical-spectroscopic technology reveals that intercalation or de-intercalation of sodium ions into/from the Prussian Blue particles happens when electrons are accepted or released by porous seawater.3)Solid-gas electron transfer bridging by porous seawater.The changes of the characteristic absorption peak of aerobic and anoxic porous seawater during electron transfer processes are compared by in-situ electrochemical-spectroscopic technology.The absorption peak changes little in the aerobic condition,however,disappears in the anoxic condition.The result suggests that there are two main processes during electron transfer:when the seawater accepts electrons from solid electrode,sodium ions are inserted into the Na Fe[Fe（CN）6]particles;when oxygen molecules accept electrons from seawater,the sodium ions are released from the Na Fe[Fe（CN）6]particles.Based on this finding,electrons can be spontaneously transferred from the light metal electrode to dissolved oxygen by replacing the anode with a reactive light metal alloy,4)Efficient electron transfer between solid-gas bridging by porous seawater.To realize large flux electron transfer,investigations are performed on the relationship between the electron transfer and the factors such as mass fractions of the solid phase,electrode structures,flow of porous seawater,and content of dissolved oxygen.The result suggests that these factors significantly affect collision probabilities between the solid electrode and porous seawater or between the porous seawater and oxygen molecules,resulting significant variation of efficiency and electron number of electron transfer.Efficient solid-gas electron transfer can be realized by optimizing all the factors.5)Prototype porous seawater batteries.Porous seawater and Al/Mg alloy are assembled into mobile and stationary prototype porous seawater batteries.Both batteries can achieve efficient and stable output of electricity.By collecting with boost modules,the mobile batteries supply electricity for lightening,moving or positioning devices,and the stationary batteries charge electronic devices such as smartphones and also drive micro control units.The tests provide practical applications of solid-gas electron transfer bridging by porous seawater in the ocean. |
