Novel Non-precious Catalysts And The Research Of Oxygen Reduction Reaction Performances In Microbial Fuel Cells

Microbial fuel cells（MFCs） integrates the microbiology and electrochemistry with materials science, which can achieve the transformation from chemical energy to bioenergy. This sustainable technology can be considered as a feasible mean to solve the phenomenon of energy crisis. The characteristics of cathode has been regarded as one of the key factors to influence the MFC performances, however, the platinum which has been viewed as the most promising cathode in regard with its high oxygen reduction reaction but the high cost hinders the application. Hence, more efforts will be taken to explore the cathode performance. This Study has been carried out based on the none-precious metal oxygen reduction reaction, the different synthesis condition as well as the application on MFC and the detail mechanism has been included. The results are as followed:（1） Using the chemical precipitation to synthesize different concentrations of NiO/CNTs（33%, 44%, 55%, 66%, 77%）. The product characteristic, electrochemical function and ORR was analyzed. The transmission electron microscope and X-ray diffraction as well as Raman investigation revealed that the prepared nanoscale NiO was attached on the surface of CNT, the crystal structure and diameter of 15²0nm was exhibited. Besides, the cyclic voltammogram and rotating ring-disk electrode tests showed that the NiO/CNT composite catalyst had apparent oxygen reduction peak, therein, the peak strength and electron transfer number was improved with the increasing concentration of NiO. Transfer pathway of 3.5 electron was acquired under oxygen atmosphere for 77%NiO/CNT. In addition, the catalyst was prepared as MFC cathode, when 77% NiO/CNT nano-sized composite was applied as cathode catalyst in membrane free single-chamber air cathode MFC, a maximum power density of 670 mW/m2 and 0.772 V of OCV was obtained. Moreover, the prepared cost was 0.3$/g. Therefore, NiO/CNT with promising ORR performance can be available as potential ORR catalyst.（2） The hydrothermal synthesis was adopted to prepare different concentrations of CoMn₂O₄/PDDA-CNTs（30%, 40%, 50%） and the prepared catalysts was coated toward the carbon cloth. The product characteristic, electrochemical function and ORR was analyzed. The transmission electron microscope, X-ray diffraction and X-ray photoelectron spectroscopy as well as FT-IR Spectrometer investigation revealed that the prepared nanoscale CoMn₂O₄ was attached on the successful non-covalent functionalization of CNT. Tetragonal crystal with the diameter of 80 nm and Co²⁺, Co³⁺, Mn³⁺, Mn³⁺was coexisted Besides, electrochemical detections as cyclic voltammogram and rotating ring-disk electrode tests showed that the CoMn₂O₄/PDDA-CNTs composite catalyst exhibited apparent oxygen reduction peaks and transited through 3.9 electron transfer pathway. Additionally The percentage of CoMn₂O₄ in the CNT nanocomposites was highly influenced the catalyst performance, when 30% CoMn₂O₄/PDDA-CNTs composite was utilized as cathode catalyst in air cathode MFC, the highest maximum power density of 1020mW/m2 and 0.781 V of OCV was obtained. The prepared product cost was 0.2$/g. Hence, CoMn₂O₄/PDDA-CNTs can realize the high ORR performance with low cost.