Preparation Of Zirconium-based Metal-organic Frameworks For Microbial Fuel Cell Applications

Energy shortage and environmental crisis seriously hinder the sustainable development of human society.However,this situation has also motivated the exploration and development of green and sustainable energy to address the most urgent global crisis.Microbial fuel cells（MFCs）have attracted extensive attention as an emerging energy technology that can degrade organic wastewater and simultaneously generates electricity.Cathodic catalysts,as the core part of the microbial fuel cells,with defective catalyst materials can weigh seriously against the overall performance and system stability of MFCs,which are the key factors hindering the large-scale marketization application of MFCs.Although precious metal Pt-based catalysts are considered as high-performance cathodic catalysts,its commercial application of MFCs have been seriously hampered by the prohibitive cost and the poor stability.Consequently,the development and synthesis of a high-performance,strong-stability and low-cost cathodic catalyst shows important application value for promoting the marketization of MFCs.Metal Organic Frameworks（MOFs）have drawn widespread attention due to their low cost,structural diversity,readily tunable pore structure and outstanding designability.In particular,UiO66 has become the research hotspot owing to its controllable morphology,large specific surface area,hierarchically porous structure and remarkable stability.In this study,a series of UiO66-derived nano catalysts were fabricated via the hydrothermal method and impregnation method.Therefore,the electrochemical performance and MFCs performance were investigated systematically.The main study results are as follows:（1）The octahedral UiO66-NH₂ nanomaterial was successfully synthesized through the hydrothermal method.Co/N co-doped nano catalysts（Co/UiO66）were successfully synthesize through the impregnation method and high temperature pyrolysis process using the UiO66-NH₂as the precursor.Among the Co/UiO66 catalysts,the Co/Ui O66-900 exhibited excellent oxygen catalytic activity under alkaline condition and displays four-electron pathway.In the MFC practical application,Co/UiO66-900 showed superb electrochemical performance with maximum power density of 1369.23 mW/m³.The superb electrocatalytic activity of Co/UiO66-900 catalyst can be mainly ascribed to the micropore structure and high active of Co-N_X,which can facilitate the oxygen reduction reaction by exposing more active sites and accelerating mass transfer at oxygen reduction reaction interfaces,thereby enhancing the ORR catalytic activity of catalyst.（2）The iron（Fe）porphyrins compound was encapsulated in the UiO66-NH₂ template by the impregnation method,and then the efficient and stable Fe-PP-UiO66 porous catalysts were successfully prepared by high temperature carbonization.Notably,the Fe-PP-UiO66 still possessed regular octahedral morphology after carbonization,which could effectively prevent the aggregation of the metal nanoparticles,thereby increasing the stability and reducing the mass transfer resistance.Besides,the implantation of iron porphyrins compound not only could be beneficial to enhance the total nitrogen content,but also generate Fe-N_X active sites and high active nitrogen species to improve the local electronic states of the carbon framework and electron transmission capability.Fe-PP-UiO66-1/3 possessed outstanding ORR performance and superior stability under the alkaline and neutral condition.The MFC with Fe-PP-UiO66-1/3 cathode showed a maximum power density of 1607.2mW/m³,and outperformed the MFC with commercial Pt/C catalyst.（3）UiO66 derived cathode catalysts show higher cost-effectiveness in both cost of catalyst and power generation cost of MFCs through the economic analysis of the cathode catalyst,which is beneficial to promote the large-scale application of microbial fuel cells.