Preparation And Photocatalytic Properties Of Biomimetic Self-healing Nanocomposite Hydrogels

With the development and use of non-renewable energy sources,people are facing the current situation of resource shortages.Looking for new energy sources is imminent.Using solar energy to produce hydrogen is one of the effective ways to generate renewable new energy sources.We learned that in nanospace,the physical and chemical properties of matter will change.When water is confined in a small space,the movement of water molecules is constrained,the evaporation enthalpy of water molecules is reduced,the migration speed of water protons is increased,and the viscosity of water increases.These properties can promote the photocatalytic hydrogen production,so we have linked the "limited range" and "catalysis" and designed a photocatalytic reaction to produce hydrogen in a limited space.Nano-composite hydrogel is a soft material with high water content.It has the conditions required for photocatalytic reaction and can be used as a reaction carrier.In this dissertation,we design a confined photocatalytic material in two parts.The first part is to obtain a nanocomposite hydrogel by compounding Pt nanoparticles with N-isopropylacrylamide.The mechanical properties and bionic self-healing properties of the nanocomposite hydrogel were explored.The best ratio of hydrogel with uniform and dense pore structure was found.In the second part,we used the nano-composite hydrogel synthesized in the first part as the carrier of the photocatalytic reaction,and explored to design a high-efficiency limited photocatalytic reaction material.The specific research content is as follows:1.Use of a functional modifier N,N-bis(acryloyl)cystamine with a sulfur atom and a carbon-carbon double bond modified platinum nanoparticles as a crosslinking agent,Functionalized platinum nanoparticles and monomer N-isopropylacrylamide were polymerized under the initiation of potassium persulfate to obtain a novel nanocomposite hydrogel.Because of the introduction nanoparticles and S-Pt R dynamic bonds,the nanocomposite hydrogel has super strong mechanical properties and excellent self-healing properties.When its tensile strain reaches 20 times,the tensile stress can reach 1.2 MPa.When the crack is placed under infrared light with a wavelength of 808 nm,the crack can heal in only 40 seconds,and the repair efficiency is 96.8%.According to the experiments in this section,we can obtain that when the content of platinum nanoparticles is 1.52mg/m L,the structure of the hydrogel is the most dense and uniform,and the pore size is all nanometer.2.Using the nanocomposite hydrogel with the best ratio obtained in the first part as a carrier for photocatalytic reaction,we composited the hydrogel with polymelamine formaldehyde(PMF)to obtain a rigid,non-swelling nanocomposite hydrogel.The gel effectively prevents the expansion of the reaction space of the swelling zone of the hydrogel.We added polypyrrole to the nanocomposite hydrogel structure to enhance its conductivity and reduce photogenerated charge-hole recombination to improve photocatalytic efficiency.When the designed nanocomposite is placed in an aqueous solution containing the photosensitizer erythrosine B(EB)and the sacrificial agent triethanolamine(TEOA),it can efficiently and quickly produce hydrogen under light,and the average output 3 hours before the reaction can reach 1507?mol/h,about 5 times the yield of 308?mol/h for an unrestricted photocatalytic reaction.