Fabrication And Performance Of Bionic Catalytic System Inspired By Bio-membrane And Photosynthesis

With the rapid development of industrialization,energy shortage,resource abuse,and environmental deterioration have become the growing problems.Therefore,it is necessary to solve these crises to ensure the quality of people’s life and the sustainable development of our country.Catalysis and surface chemistry,the basis of energy and material transformation,is one of the approaches to solve the major needs of energy,environment,resources,information,and health.It is of significance to expand interfacial catalysis and photocatalysis areas by integrate the new ideas and methods to overcome above challenges.Learning from nature including special structure material of organisms,transmission,and energy conversion to design catalysts and improve the efficiency of catalysis has attracted much interests in materials and chemistry field.In this dissertation,a series of bionic systems including dual-enzyme cascade biphasic system involved colloidosomes,cross-membrane hydrogen evolution system with colloidosomes,and photocatalytic systems based on bionic g-C₃N₄catalysts have been designed through mimicking the structure and functions of biological membrane as well as the process and mechanism of photosynthesis.（1）Inspired by the phenomenon that minbillions of cells and organelles function as micro-compartments and active sites in confined spaces for various enzymatic biochemical cascades,a novel method for the construction of colloidosome as a microreactor for dual-enzyme cascade biphasic reaction have been designed.Amphiphilic nanoparticles were prepared through the surface modification of Si O₂nanoparticles.Moreover,these amphiphilic Si O₂nanoparticles can be used as surfactant to fabricate a Pickering emulsion,in which dropts were crosslinked with trimethoxymethylsilane（TMOS）for stable colloidosome to transfer into aqueous solution.A water-soluble enzyme glucose oxidase（GOx）is compartmentalized inside the colloidosomes,while Candida Antarctica lipase B（Cal B）is adsorbed on the outer surfaces of the colloidosomes.A catalysis system is set up by introducing these dual-enzyme-immobilized microcapsules into acetic ether.Finally,the formed peracids oxidized N-heteroaromatic in situ.Furthermore,no obvious yield decline is observed in four reaction cycles.（2）Inspired by the phenomenon that the light reaction and dark reaction of photosynthesis carrying out in individual space to avoid side reactions,a cross-membrane hydrogen evolution system using colloidosomes as the microreactors was conducted.The am LUDOX nanoparticles with negative charges were obtained by the modification of hydrophilic LUDOX nanoparticles.The colloidosomes contained Pt nanoparticles inside were prepared by am LUDOX nanoparticles as the building block and crosslinked by TMOS.The photocatalytic hydrogen-generated system has been achieved by using 5,10,15,20-（4-sulfonatophenyl）porphinato]zinc（II）（Zn TPPS）as the photosensitizer,pyrylium ions and N-methyl-4-cyanopyryidinium iodide（MCP）as the electronic carriers.Our work proves the practicability of this system.To further improved its efficiency,a photostable semiconductor g-C₃N₄is applied instead of the unstable organic photosensitizer.An optimized bionic cross-membrane hydrogen production system system is obtained by using g-C₃N₄to harvest the light energy and MCP to deliver the electrons.（3）Inspired by the Z-scheme chain of electron transport in photosynthesis,a direct Z-Scheme Fe₂（Mo O₄）₃/oxygen doped g-C₃N₄nanosheet（FM/OCN）catalyst with Fe（δ+）-N（δ-）-C（δ+）or Fe（δ+）-O（δ-）-C（δ+）covalent bonding states was established successfully for enhanced photo-Fenton degradation.Moreover,the photo-Fenton system was further improved degradation efficiency for the introduction of H₂O₂,which because Fe³⁺can be inverted H₂O₂into·OH.And,the efficiency of degradation can be affected by the charge transfer pathway.Besides,the influence of electron and hole scavengers for Rh B photodegradation efficiency were investigated as well.An ultra-efficient photodegradation system of Rh B has been established using OCN as the photocatalyst,from which energy is harvested on both conduction band and valence band by formic acid（FA）and H₂O₂,respectively.The mechanism of this photodegradation involves enhanced charge carrier migration and generation of multiple radicals,which could be a common characteristic to semiconductor photocatalysts,such as Ti O₂,Zn O,Fe₂O₃,and Si C.（4）A novel phosphorus and oxygen co-doped g-C3N4（POCN）with enhanced photocatalytic performance has been fabricated through a facile one-step process from functional bionics,in which ammonium polyphosphate（APP）has been employed as the phosphorus precursor for the first time.Compared with pristine g-C₃N₄,the H₂evolution rate increases as well as the apparent degradation rate.As there are plenty NH₄⁺group in APP molecule,lots of released gas was generated during calcanination,such as NH₃,CO₂,PH₃.Aside from the element doping,the initial crystalline bulk g-C₃N₄has been reconstructed by the released gas.Therefore,all as-prepared photocatalysts shows a concurrent increase of the band gap,but a gradual blue shift of the band is observed as the phosphorus content rises.Overall,the enhancement of photocatalysis can be mainly attributed to the enlarged surface areas,abundant active sites,reduced diffusion distance,and efficient charge separation.