Preparation Of Highly Defect Graphene Nanospheres Supported Platinum Catalysts For Hydrogen Evolution Reaction

Hydrogen energy,a renewable energy source,has high energy density,zero-pollution and abundant resources,which has attracted wide attention and has broad application prospect.At present,industrial hydrogen production technology not only consumes a lot of fossil fuels,emits large amounts of pollutants,but also causes some harm to human health.Therefore,exploring a clean,sustainable,and effective method for hydrogen production method will be the focus of attention.Electrochemical water splitting to produce hydrogen?H₂?offers a new type of technology,that promising and sustainable solution for this purpose by converting such electricity energy into stable chemical bonds.An effective catalyst is favorable for reducing the hydrogen evolution reaction overpotential,increasing the catalytic reaction rate.The supported catalysts play an important role in the process of hydrogen production by electrochemical reduction of water,which have high activity and good stability.The supported Pt-based catalysts have widely used in various catalytic reactions.The arc discharge is a method,which can effectively prepare high-defect carrier,the characteristics of carrier can not only expose the active site of Pt,but also inhibit the agglomeration of the metal particles,so that improving the catalytic activity.In this dissertation,hexahydrate chloroplatinic acid?H₂PtCl₆·6H₂O?was used as precursor material,preparation of Pt-based catalysts by arc discharge method and studied the performance of Pt-based catalysts in hydrogen production.Firstly,the graphene nanospheres?GNs?carrier were prepared by arc discharge method using toluene as a carbon source by arc discharge in toluene solution.The results were characterization by SEM,STEM,Raman,XPS,XRD and FT-IR.GNs have a high density of lattice disorder,and the edges contain ultra-thin graphene nanoplatelets,as well as high defects and high oxygen-containing functional groups.The Pt-based catalysts were successfully prepared by incipient wetness impregnation?IWI?method with H₂PtCl₆ as metal precursor at100°C for 1 h mildly under a 10%H₂ flow?with balance Ar?.The ICP results showed that the loadings of different catalysts were 1.8,4.7,8.8,14.7 and 19.6 wt.%.The TEM results showed that the Pt particles in the prepared catalysts have a more uniform distribution and the average particle size was about 2.6,2.5,2.6,2.8 and 3.0 nm.The series of catalysts exhibited higher catalytic activity in the hydrogen evolution reaction.With the increase of the loading,the catalytic activity also increased.Among of them,the hydrogen evolution performance of the catalyst showed the best performance with a loading of 14.7 wt.%,and the particle is 2.8 nm.At a current density of-10 mA cm^-2,the overpotential is-25 mV and the Tafel slope is-33 mV dec^-1.At the same time,the catalyst has excellent stability,and the overpotential increase by 4mV after 1000 cycles.Secondly,using H₂PtCl₆·6H₂O as the metal precursor,anhydrous ethanol@H₂PtCl₆solution was prepared.A small amount of anhydrous ethanol@H₂PtCl₆ solution was added to the toluene solution and stirred rapidly.After that,the low-loading Pt/GNs catalysts were obtained in-situ by arc discharge.The EDS results indicated that the Pt loading was approximately 0.62,0.45,and 0.21 wt.%.TEM characterization showed that there existed agglomeration of Pt in the Pt/GNs catalysts,and the edge particles were dispersed uniformly.The average particle size was about 2.2,3.1 and 1.2 nm.The in-situ loading catalysts showed good hydrogen evolution performance in the hydrogen evolution reaction.Among of them,the hydrogen evolution performance of the catalyst showed the best performance with a loading of0.45 wt.%,and the particle is 3.1 nm.At a current density of-10 m A cm^-2,the overpotential is-46 mV and the Tafel slope is-37 mV dec^-1.At the same time,the catalyst has excellent stability,and the overpotential increase by 5 mV after 1000 cycles.