Preparation And Properties Of Platinum Nanocomposites

At present,the new technology revolution has ushered in the opportunity of rapid development,which has put forward higher requirements for the functionality of metal nanomaterials.A single metal nanomaterial can no longer satisfy people as the need arises,metal nanocomposites have emerged at the historic moment,which can not only maintain the characteristics of platinum nanoparticles but also take into account the advantages of other materials,and once became a research hotspot.In the field of metal nanocomposites,platinum-based nanocomposites have the advantages of good chemical,physical properties and high stability,and have a wide application prospect.However,in the preparation of platinum-based nanocomposites,the performance of the support material is very critical,and it has a great influence on the formation process,particle size and stability of platinum nanoparticles.Therefore,in this paper,polyaniline with special morphologies and resin polymers were selected as carriers,and Pt@DHPANI nanocomposites and Pt@D201 nanocomposites were prepared by simple adsorption method and one-step reduction method,the morphology,formation mechanism and catalytic performance were discussed.The specific research contents are as follows:1.Effects of different resin types and experimental conditions on PtCl₆^2-ions adsorption reactionIn this paper,three resins D201,717,and LSC200 were selected as research objects.By measuring their adsorption capacity for PtCl₆^2-ion,D201 resin with high adsorption performance was selected and used as a carrier for the preparation of platinum nanocomposites.At the same time,the experimental conditions such as pH,temperature and stirring speed of the solution were changed,and the influence of each factor on the adsorption performance of the resin was studied.Through continuous optimization,it was found that the optimal conditions for the PtCl₆^2-ion adsorption reaction were when the solution had a pH of 6,a temperature of 30℃,and a stirring speed of 200 r/min.2.Preparation and Properties of Pt@DHPANI NanocompositesThrough simple solution polymerization method,with the addition of C₁₈-L glutamic acid as a template and without template,polyaniline（DHPANI）with double helical nanotube morphologh and polyaniline（PANI）with no fixed morphology were prepared,respectively.Comparing the two samples,it was found that DHPANI has better adsorption performance for PtCl₆^2-ions.In addition,through the control variable method,it was found that when the monomer mass is 25 mg and the template mass is 4 mg,polyaniline with stable and ordered double helix morphology can be prepared.Then,Pt@DHPANI nanocomposites was prepared by one-step reduction method using polyaniline as a carrier,formaldehyde as a reducing agent,and potassium chloroplatinate as a platinum source.Characterization results indicate that the material has good and stable double helix morphology,the hollow nanotubes have an outer diameter of about 100 nm and an inner diameter of about 20 nm,Pt nanoparticles are distributed on the surface of the composite material,the particle size is about 50 nm,and no agglomeration occurs.This special double-helix hollow tubular structure greatly increases the specific surface area of polyaniline.At the same time,it was found that the enhanced interaction between Pt nanoparticles and DHPANI makes it more difficult for Pt nanoparticles to lose electrons and thus become more stable.In order to explore the catalytic performance of Pt@DHPANI nanocomposites,it was used as a catalyst for the catalytic reduction of 4-NP.When the dosage is only 1 mg,the conversion rate of 4-NP can reach 99%within 7 minutes.It is twice the catalytic efficiency of Pt@PANI nanocomposites under the same conditions,and has excellent and stable catalytic performance.3.Preparation and Properties of Pt@D201 NanocompositesUnder the conditions of a solution temperature of 30°C,a pH of 6,and a stirring speed of 200 r/min,a series of Pt@D201 nanocomposites with different Pt loadings were prepared.They were added to the reduction reaction of p-nitrophenol,their catalytic performance was examined,and the influence of the loading amount of platinum nanoparticles on the catalytic performance was investigated.Test results found that with the increase of the platinum loading,the catalytic performance of the nanocomposites continues to improve.When the loading is only 0.05%,it also has a certain catalytic effect.However,based on the reaction time and rate,it is most appropriate to select Pt@D201 nanocomposites with a loading of 0.1%as the catalyst.The stability of the composites was explored through a cyclic reaction test,when the cycle was performed for the third time,the conversion rate of the reactants could still reach 85%.