Study On The Controlled Preparation Of Platinum Particle Morphology

In this paper,chloroplatinic acid is used as a precursor to prepare platinum particles with different morphologies under different systems.Field emission scanning electron microscope(FESEM),X-ray energy spectrometer(EDS),transmission electron microscope(TEM),and X-ray diffractometer are used.(XRD),laser particle size analyzer(LPSA)and other testing and analysis methods,starting from three different experimental systems,respectively prepared dendritic platinum nanoparticles,rod-shaped platinum particles and plate-shaped platinum particles Explore the effects of process parameters on the products in different experimental systems:the effect of reducing agent concentration and stirring rate on platinum nanoparticles;the effect of oleic acid-oleylamine ratio and heating temperature on rod-shaped platinum particles;the effect of external electric field frequency and solvent type on the flake platinum particles.The formation mechanism of platinum particles with different morphologies was studied and the conclusions are as follows:1.Using platinum particles prepared with chloroplatinic acid as the precursor and sodium borohydride as the reducing agent have serious agglomeration,and hydrazine hydrate as the reducing agent can produce dendritic platinum nanoparticles with good dispersibility.The reaction temperature is 100℃,the reaction time is 2 h,the amount of dispersant PVP is 0.02 g,and the rotation speed is 200 r/min,which are excellent process parameters for the preparation of dendritic platinum nanoparticles.Hydrazine hydrate is more suitable as a reducing agent for this reaction system than sodium borohydride.The growth process of dendritic platinum is to first form new active sites on the platinum particles of truncated cubic structure along the(111)and(220)directions,and form new crystal nuclei on the surface of the platinum nanoparticles.After the grain growth process,new nuclei are formed on the surface,and this process is repeated to form a dendritic structure2.Using chloroplatinic acid as the precursor,by heating in the oleic acid-oleylamine system,the reaction can prepare rod-shaped platinum particles with a length of tens of microns and a diameter of several microns.The ratio of oleic acid to oleylamine is 1:At 3 o’clock,the heating temperature was 150℃,the reaction time was 4 h,and the amount of PVP dispersant was 0.05 g to obtain rod-shaped platinum particles with an aspect ratio of 20:1.The growth process of rod-shaped platinum is that platinum particles have new crystal nuclei formed along the(111)direction at the active site provided by oleylamine.After the new crystal nuclei have grown up,new ones appear in the(111)direction Crystal nucleus,repeat this process,and during the nucleation and growth of the grain,due to the bond between oleic acid and platinum,the growth of other crystal planes is inhibited,and finally a rod-like structure is obtained3.Chloroplatinic acid as a precursor,ethylene glycol as a reducing agent,absolute ethanol as a solvent,heating temperature of 180℃,reaction time of 1 h,and applied electric field frequency of 50 Hz are excellent process parameters for the preparation of flake platinum particles.The growth process of flake platinum particles is dominated by the electric field force,and the process of accumulating ions in the two-dimensional direction in the direction of the electric field.