Study On Light-enhanced Microbial Fuel Cells

Microbial fuel cell(MFC)is an attractive and promising sustainable energy technology which can continuously extract electrical energy from organic waste by microorganism catalysis.MFC can not only be utilized as energy output device,but also for wide applications,such as environmental monitoring,biomolecular detection,microbial activity assessment,and hydrogen evolution.However,the main factor limiting the development of MFC is still the lower energy output density.Therefore,introducing the free and inexhaustible solar energy into MFC system to achieve multiple energy conversion is promising.In this dissertation,by considering both the anode engineering and the cathode construction,we have explored the new light-enhanced MFC system to achieve high power output performance,making the base for the widely application of'MFC in other fields.The main contents are as follows:1.Visible-light-enhanced power generation in microbial fuel cells coupling with three-dimensional nitrogen-doped graphene self-standing spongeAs two indispensable parts of MFC,anode and cathode reactions have inherent impact to electricity production.Herein,a novel three-dimensional nitrogen-doped graphene self-standing sponge(3D NG-SS)is fabricated as high-performance bio-anode material.Owning to its high electrical conductivity and suitable porous structure for microorganism colonization,the fuels were rapidly oxidized by biocatalyst on the anode,leading to the superior performance of MFC.Moreover,based on the construction of 3D NG-SS anode,we innovatively induce the inexhaustible and low-cost solar energy to MFC cathode system,a new hybrid system--visible-light-assisted MFC(VLA-MFC)is successfully developed by substituting photoresponsive cathode for the regular carbon paper electrode,contributing to further increasing of power output,as high as 2601 mW/m2.As a result,the proposed VLA-MFC coupling with the 3D NG-SS anode achieves excellent power output and multiple energy conversion routes,effectively improving the energy utilization efficiency.This work not only provides new promising construction of ultra-high-performance MFC,but also shows new utilization ways of energy conversion and storage.2.Plasmon-enhanced Cathodic Reduction for Accelerating Electricity Generation in Visible-light-assisted Microbial Fuel CellsVisible-light-assisted microbial fuel cells(VLA-MFCs)possess great potential,in which novel photoelectric conversion process was integrated into the conventional microbial electricity generation,thus multidimensional energy conversion routes can be achieved.In this regard,developing high-efficiency photoelectric conversion strategy to obtain high performance of VLA-MFCs is highly desirable.Herein,we present a promising plasmon-induced hot-electron transfer system in which three-dimensional Cu2O@plasmonic Au nanowire array was first synthesized and used as the photocathode for accelerating electricity generation of the VLA-MFC.Owning to the surface plasmon resonance excitation of Au nanocrystals,hot electrons can be generated and injected into the adjacent Cu2O semiconductor nanowire array for significantly enhancing the cathodic reduction reaction,eventually resulting in the improved performance of the VLA-MFC.3.Boosting Bio-electricity Generation of Individual Coated Bacterial Cells using N,S-doped Carbon Dots as Dual-functional ModifiersA high-efficiency extracellular electron transfer(EET)of exoelectrogens from the inside of the outer membrane to the external environment is of great importance in the bioelectrochemical research.In this regard,developing functional coatings for individual bacteria,meanwhile integrating efficient photo-assisted conversion process by introducing abundantly available solar energy possess huge potential to achieve excellent EET.Herein,a practical strategy of coating individual bacterial cells by using photo-responsive N,S-doped carbon dots(m-NSCDs)is proposed.This suggested that the m-NSCDs coatings can act as dual-functional modifiers which not only afford enhanced conductivity of bacterial cells without affecting viability,but also serve as photosensitizers to achieve light-assisted catalytic process.Specifically,this novel design enables the simultaneous utilization of light-and electrochemical energy,yielding a superior power output performance in the microbial electrochemical systems.