Preparation Of MXene/ Polypyrrole Hydrogel And Its Application In Microbial Fuel Cells

Microbial fuel cell（MFC）is a novel green,sustainable,and highly efficient energy technology with broad application prospects.It combines the characteristics of electricity generation and organic wastewater treatment,and has attracted widespread attention from scholars in the field of sustainable new energy due to its clean and low-cost advantages.The anode material of MFC is a key factor that affects and limits its electricity generation performance.Three-dimensional conductive hydrogel materials exhibit excellent electrochemical performance and biocompatibility,and the electricity generation performance of MFC is closely related to these material characteristics.Therefore,in this study,hydrophilic and conductive two-dimensional transition metal carbide（Ti₃C₂T_x MXene）material was selected to prepare three-dimensional conductive MXene-poly pyrrole hydrogel material,which was applied as a biological anode in MFC.Subsequently,the MXene material was modified by introducing phosphorus and nitrogen elements with good microbial affinity,and the effects of different intercalation materials and intercalation methods on the electricity generation performance of the hydrogel anode in MFC were studied based on this.A three-dimensional porous MXene-polypyrrole（MXene/PPy）hydrogel with outstanding conductivity was successfully prepared by in-situ chemical oxidation.FTIR and XRD analyses confirmed the successful preparation of the material,while SEM revealed the significant three-dimensional porous structure of the MXene/PPy hydrogel,which is favorable for the colonization of exoelectrogenic microorganisms on the surface and interior of the anode.Electrochemical performance testing demonstrated that MXene/PPy-10 was the optimal composite ratio material,possessing lower charge transfer impedance and faster electron transfer rate.When applied as an anode in an MFC,the MXene/PPy-10 hydrogel exhibited a maximum power density of 5.26 W/m³,a 61.85%improvement over the PPy hydrogel anode MFC（3.25 W/m³）.Additionally,the high hydrophilicity of MXene effectively enhanced the biocompatibility of the anode.The protein content of the MXene/PPy hydrogel bioanode（42.95mg/cm²）was 47.29%higher than that of the PPy bioanode（29.16 mg/cm²）.Phosphorus-doped MXene was prepared by annealing MXene nanosheets in the presence of sodium hypophosphite,and a phosphorized MXene-poly pyrrole（P-MXene/PPy）hydrogel material was synthesized.XPS and FTIR analysis showed successful insertion of phosphorus into the MXene and formation of P-MXene/PPy hydrogel.SEM analysis revealed the formation of thicker and crumpled MXene nanosheets after annealing,with PPy uniformly grown around the phosphorus-modified MXene nanosheets.Electrochemical testing demonstrated that the phosphorus-modified MXene material effectively improved the electrochemical performance of the hydrogel.The P-MXene/PPy-5 hydrogel with the best electrochemical performance was used as a bioanode in an MFC,achieving a maximum power output density of 7.87 W/m³,which was 49.62%higher than that of the MXene/PPy hydrogel anode MFC（5.26 W/m³）.Meanwhile,phosphorus-intercalated MXene effectively improved the biocompatibility of the anode,with the protein content of the P-MXene/PPy-5 hydrogel bioanode（59.07 mg/cm²）increased by 37.53%compared to that of the MXene/PPy-10 bioanode（42.95 mg/cm²）.The aminoized MXene/polyaniline（N-MXene/PPy）hydrogel material was prepared by using the liquid-phase coagulation method to reassemble and aggregate MXene nanosheets,followed by the electrostatic adsorption intercalation of NH₄⁺into MXene.XPS and FTIR analyses demonstrated the successful insertion of NH₄⁺into MXene,leading to the formation of N-MXene/PPy hydrogel.Modified MXene increased the surface positive charge of the material,which facilitated the attachment and growth of electricity-generating microorganisms with negatively charged surfaces on the anode surface,thereby increasing the biomass amount on the bioanode surface.The protein content test showed that the protein content of the bioanode with the best electrochemical performance,N-MXene/PPy-1 hydrogel,was 69.90mg/cm²,which was 70.15%and 13.72 higher than that of the MXene/PPy-10 bioanode（42.95mg/cm²）and P-MXene/PPy-5 bioanode（59.07 mg/cm²）,respectively.The electrochemical test showed that the charge transfer impedance of the N-MXene/PPy-1 bioanode was only 0.84Ω,and its maximum power density of the microbial fuel cell（MFC）reached 8.95 W/m³,which was 70.15%and 13.72%higher than that of the MXene/PPy-10 electrode MFC（5.26 W/m³）and P-MXene/PPy-5 electrode MFC（7.87 W/m³）,respectively.