Preparation Of Molybdenum-based Compound Modified Graphene Aerogel And Its Properties In MFC

Microbial fuel cells（MFCS）,as an efficient,clean and pollution-free means of energy,are expected to be widely used in the fields of power supply,wastewater treatment,and biosensors.At present,the low output power of microbial fuel cell is still a problem,which limits its practical application.As the carrier of electrogenic microorganisms,anode directly affects the extracellular electron transfer efficiency of electroactive biofilms,thus determining the electrogenic performance of MFC.Therefore,it is of great significance to develop anode materials with excellent bioelectrocatalytic activity to improve the output power of MFC.Graphene aerogel material has the advantages of good conductivity and high porosity,and has been widely used in MFC.In order to further improve the electrocatalytic activity and biocompatibility of graphene aerogel,molybdo-based nanomaterials with heteroatomic phosphorus or polydopamine and electrocatalytic activity were combined with graphene aerogel in this paper to prepare molybdo-based compounds modified graphene aerogel,and its performance in MFC was evaluated.The main research contents are as follows:Microbial fuel cells（MFCS）,as an efficient,clean and pollution-free means of energy,are expected to be widely used in the fields of power supply,wastewater treatment,and biosensors.At present,the low output power of microbial fuel cell is still a problem,which limits its practical application.As the carrier of electrogenic microorganisms,anode directly affects the extracellular electron transfer efficiency of electroactive biofilms,thus determining the electrogenic performance of MFC.Therefore,it is of great significance to develop anode materials with excellent bioelectrocatalytic activity to improve the output power of MFC.Graphene aerogel material has the advantages of good conductivity and high porosity,and has been widely used in MFC.In order to further improve the electrocatalytic activity and biocompatibility of graphene aerogel,molybdo-based nanomaterials with heteroatomic phosphorus or polydopamine and electrocatalytic activity were combined with graphene aerogel in this paper to prepare molybdo-based compounds modified graphene aerogel,and its performance in MFC was evaluated.The main research contents are as follows:Firstly,the graphene aerogel doped with excellent electrical conductivity and electrocatalytic activity was prepared by hydrothermal and high-temperature calcination method.The maximum output power density of Mo O₂/GA as anode in MFC was 3024 m W/m²,2.19 times that of graphene aerogel（GA）.Electrochemical analysis showed that the charge transfer resistance between Mo O₂/GA and electroproducing biofilm was only 44Ω,much lower than GA（248Ω）.Mo O₂ doping can promote the extracellular electron transfer between the electroproducing biofilm and the electrode,improve the bioelectrocatalytic efficiency of the electrode interface,and enhance the bioelectricity collection and storage capacity of the electrode.The aerogel electrode with three dimensional porous structure can provide more attachment sites for microbial colonization.Mo O₂ doping promoted the enrichment of functional electrogenic bacteria on the electrode surface.The relative abundance of Geobacter on Mo O₂/GA surface was 66.2%.Graphene aerogel doped with heteroatomic phosphorus,molybdenum dioxide and phosphorus was further introduced on GA and Mo O₂/GA surfaces by hydrothermal and high-temperature calcination.The doping of heteroatomic phosphorus significantly improved the electrochemical activity of GA and Mo O₂/GA.The maximum output power density of Mo O₂/PGA in MFC reaches 3455 m W/m²,which is nearly 14.2%higher than that of Mo O₂/GA（3024 m W/m²）.The maximum output power density of PGA in MFC reaches 2271 m W/m²,which is nearly 64.8%higher than that of GA（1378 m W/m²）.Microbial analysis showed that Mo O₂/PGA had the best bacterial loading capacity（total protein content 52.45 mg）and Geobacter enrichment and screening ability（73.8%）.The above results show that the electrocatalytic activity,biocompatibility and charge storage capacity of GA are significantly improved through the co-doping of Mo O₂ and P,and the electricity generation performance of MFC is greatly improved.In order to further improve the electrocatalytic activity and biocompatibility of GA,two-dimensional molybdenum carbide MXene and polydopamine co-doped graphene aerogel（MXene/PDA/GA）was synthesized by hydrothermal method.MXene/PDA/GA shows the advantages of fast start-up speed,high charge transfer efficiency,high electrocatalytic activity and large bacterial load.MXene/PDA/GA（14.06Ω）has lower charge transfer resistance than GA（248Ω）,MXene/GA（15.72Ω）and PDA/GA（19.24Ω）.Exhibited the most excellent electrocatalytic activity.The above results show that the three-dimensional porous network structure with good conductivity,high electrocatalytic activity and good biocompatibility is constructed by the composite of two-dimensional molybdenum carbide MXene,polydopamine and graphene,which can promote the establishment of efficient electron transport network between electrogenerating biofilm and electrode interface,and effectively improve the electrical performance of MFC.