Design Of Porphyrin-based Nanomaterials And Their Electrochemical Energy Storage Performanc

Along with the increasing demands for high performance energy storage device with high energy density,long-term cycling stability and high rate capability,energy-type lithium-sulfur（Li-S）batteries and power-type supercapacitors have shown promising potentials that promoting the persuit of high performance electrode materials.Porphyrin and its derivatives exhibit unique advantages in energy storage materials.（1）To bestow conductive polymer enhanced bulk conductivity,chemisorptions to polysulfides and catalytic activity,herein,5,10,15,20-tetrakis（4-sulphophenyl）porphyrin（TPPS）cross-linked polypyrrole（PPy）nanocomposites（named PPy-TPPS）is rationally fabricated as an integrated polymeric host by aqueous self-assembly through the interaction between-SO₃^-and-NH=⁺.PPy-TPPS nanocomposites exhibit peag-like chain in morphology with hierarchical porous structure and high pore volume.The rigid conjugate TPPS molecules bridge linear PPy chains to extend the conjugate system,construct a multipath electron highway,create a three-dimensional conductive network and greatly reinforce the bulk conductivity of the nanocomposites.The unique structural features expose plenty of N sites to enhance the chemically anchoring polysulfides,suppress polysulfide diffusion,and release the shuttle effect.Both experimental and theoretical calculation confirms the enhanced polysulfide trapping ability.The presence of TPPS also bestows the PPy-TPPS/S cathode catalytic property to promote the Li₂S nucleation rate and accelerate the reversible solid-liquid conversion between Li₂S and soluble polysulfides.The improved conductivity and enhanced polysulfide affinity with catalytic property render PPy-TPPS nanocomposites improved Li-S battery performances with high specific capacity,high rate capability,and high cycling stability.The PPy-TPPS/S cathode delivers a high initial capacity of 1278 m Ah g^-1 at0.2 C.The cathode exhibits an initial discharge capacity of 761 m Ah g^-1 at 2 C with residual capacity of 470 m Ah g^-1 after 500 cycles.（2）Using PPy-TPPS as the pillar,PPy-TPPS/MXene film is fabricated by intercalating conductive PPy-TPPS into MXene nanosheets through interlayer hydrogen bonds.Intercalation arouses the augmented interlayer spacing of MXene increases from 1.20 to1.42 nm.The alternatively aligned MXene and PPy-TPPS create 3D interconnected conductive networks to accelerate the ionic/electronic transport rates.PPy-TPPS/MXene film exhibits high chemical stability due to a favorable tolerance to volume change during the charge/discharge process.The PPy-TPPS/MXene film delivers a capacitance of 1994.8 m F cm^-2 at 1 m A cm^-2.The flexible symmetric supercapacitor shows an areal capacitance of 397.3 m F cm^-2 with areal energy density of 109.9μWh cm^-2 and power density of 1.8 m W cm^-2.（3）CoTPP/MXene composites are prepared via static self-assembly.The strong interfacial interaction and good electronic coupling between the CoTPP nanoparticles and MXene nanosheets not only improve the structural stability,electrical conductivity,and electrolyte accessibility but also greatly boost the redox kinetics.The CoTPP/MXene electrode exhibits prominent conductivity and supercapacitive behavior.It delivers a capacitance of 282.8 F g^-1 at 1 A g^-1.The symmetric supercapacitor displays an energy density of 12.7 Wh kg^-1 and power density of 808.7W kg^-1.（4）Graphene interconnected N-doped 3D carbon frameworks with dispersive Fe₃C/Fe nanoparticles（Fe₃C/Fe@NC-G）are produced by pyrolyzing GO wrapped self-assembled porphyrin organic framework（POF）.Graphene serves as a 2D conductive support to connect the Fe₃C/Fe@NC units into a robust 3D network.The porous structure facilitates electrolytic ion diffusion on Fe₃C/Fe nanoparticles during charge storage.The metallic iron is benefit to enhance the electronic conductivity.As expected,the Fe₃C/Fe@NC-G delivers a discharge capacity of 240.8 F g^-1 under a current density of 1A g^-1.It achieves a high capacity retention of 92.6%after 10000charge-discharge cycles that demonstrates high cycling stability.Furthermore,the symmetric supercapacitor exhibits a high energy density of 12.71 Wh kg^-1 at a power density of 28.8 k W kg^-1.（5）Conductive porous Fe₂O₃ hybrided N doped porous carbon（Fe₂O₃/N-PC）is designed via pyrolyzing Hemin/AC composites.The porous structure affords high surface area and conductive channels for the rapid diffusion of electrolyte ions and electrons during the charge-discharge process.The redox reactions of iron oxides particles and N heteroatoms contribute pseudocapacitance to greatly enhance the supercapacitive performances.Fe₂O₃/N-PC achieves a high capacitance of 290.3 F g^-1at 1 A g^-1 with high capacity retention of 93.1%after 10000 charge-discharge cycles.Solid symmetric device delivers a high energy density of 37.6 Wh kg^-1 at a power density of 1.6 kW kg^-1.