Preparation Of Carbon-based Platinum Nanocrystalline Composite Catalytic Material And Its Application In Catalytic Hydrogen Production

With the continuous increase of global energy demand,searching for emerging alternative energy has attracted wide attention from researchers all over the world.Hydrogen energy,as a type of secondary energy,shows a lot of advantages such as clean,efficient and safe properties,and has been considered as an ideal green energy for the industry.Hydrogen production by electrolysis of water is an important technology for the large-scale production of high-purity hydrogen.Platinum,precious metal,have shown excellent application prospects in various fields due to its highefficiency catalytic properties.But its scarcityand high price limit its further development in the hydrogen energy industry.In the field of energy,the researchers combined carbon and precious metals into composites,it has been proved to be an effective method to reduce the cost and improve the catalytic activity and stability of catalysts.By optimizing the composition,morphology,nanostructure and carrier of nanocrystalline,the catalytic activity and stability of the catalysts were improved.Electrochemical deposition is a simple method to prepare metal nanostructures.The hydrogen evolution catalyst prepared has excellent performance and stability,and has a good prospect in the field of catalytic hydrogen production.In this paper,platinum nanocrystalline catalysts were fabricted by electrochemical deposition method.Platinum carbon composite catalysts with nano-size and regular shape were obtained by adjusting the conditions of electrochemical reaction.The morphology,structure and components of the prepared catalyst were analyzed by scanning electron microscope(SEM),transmission electron microscope(TEM),X-ray diffraction(XRD)and electronic energy spectrum(EDS),and the electrochemical properties of the catalyst were studied by electrochemical testing.The main research contents are as follows:(1)Platinum nanoparticles(Pt nanocrastals/Pt)and Pt nanocrastals/activated carbon(Pt nanocrastals/activated carbon)were deposited on pure platinum sheets and activated carbon by electrodeposition with constant potential.The morphology changes of Pt nanoparticles deposited under different deposition conditions were observed by SEM.It was concluded that NH4+ and Cl-ions in electrodeposition liquid could be applied as crystal modifiers in the process of electrodeposition at a constant potential,leading to the formation of uniform and regular nanocrystals.Free Pt dendritic structure can be obtained under high overpotential and long-time deposition.The activated carbon,as substrates to fabricate Pt nanocrystals,was tested by electrochemical linear sweep method to assess the constant potential electrochemical catalytic activity of Pt nanocrystals,under the constant voltage of 0.6 V.The electrolyte is 10 m M((NH4)2Pt Cl6),7.5 m M(Pt Cl4).After the 600 s sedimentary,the cone nanocrystals were successfully prepared with the low potential(0.030 V),and low Tafel slope(23.83 m V/dec).In the hydrogen evolution reaction showed good catalytic activity.(2)The reasons for the excellent catalytic activity of the carbon-based platinum nanodendrites composite catalyst(Pt NDS@AC)were systematically analyzed.Due to its unique structure,Pt NDS@AC has a large area of electrochemical activity and exposed crystal face(111),which effectively increases the specific surface area of the catalyst and improves the catalytic performance of the catalyst.In acidic solution,the current density is 10 m A/cm2 with a low overpotential of 0.027 V,and the Tafel slope is as low as 22.2 m V/dec.Pt NDs@AC can produce hydrogen in aqueous solutions with different p H values,and its yield is 30% ~ 45% higher than that of commercial catalysts under the same Pt load.Moreover,after continuous reaction for 6 h or 5000 CV cycles in 0.5 M H2SO4 solution,the Pt NDs@AC catalyst still showed excellent stability.