Preparation Of Platinum-Copper Electrocatalysts And Their Performance Toward Hydrogen Evolution Reaction

The hydrogen adsorption free energy of precious metal like Pt is near zero,which can be considered as the most ideal catalyst for hydrogen evolution reaction（HER）.Although Pt is expensive and rare,Pt-based nanomaterials are still irreplaceable catalysts for HER.Therefore,the design of a new type of Pt-based nanocatalysts to maximize the use of Pt and improve the activity of the catalysts has become urgent.Based on the current reports that the catalytic activity of Pt-based nanomaterials are closely related to their compositions,support and surface structure.It is helpful to construct high performance hydrogen evolution catalysts by adjusting these key factors,so as to improve the utilization of Pt.Generally,doping Pt with transition metals to form bimetallic nanocrystals can accelerate the reaction rate.The obtained Pt-Cu nanomaterials are applied to the hydrogen evolution reaction of electrolysis of water.The specific research works are shown below:（1）Considering that the surface structure of Pt-Cu bimetallic nanocrystals is the main factor affecting the activity of hydrogen evolution,the nucleation growth of nanocrystals is regulated by kinetics,Pt-Cu decahedral nanoframes（Pt-Cu NFs）rich in twin defects was constructed.Firstly,the effects of the type and the added amount of precursors,as well as the volume ratio of oleylamine and oleic acid on the morphology and surface structure of Pt-Cu bimetallic nanocrystals were investigated.Additionally,based on the unique interaction between twin seed and oxidation etching agent,the morphologies and size of Pt-Cu bimetallic nanocrystals were further obtained.The formation mechanism of was further characterized and analysized by collecting the products at different reaction time.In order to study the HER properties of Pt-Cu NFs,commercial Pt/C catalyst was selected as a comparison.The results indicate that the Pt Cu_1.8 catalyst has high activity and excellent stability.（2）The support used in the electrocatalytic hydrogen evolution test based on Pt-based catalysts also has a certain effect on its catalytic activity.Considering that the surface properties of molybdenum carbide（Mo C_x）are similar to those of precious metals,the porous Cu/Mo C_x nanomaterials were obtained by carbonization of metal-organic frameworks（MOFs）and polyoxometalates（POMs）,and with the bimetallic nanocrystals were formed by alloying Pt with Cu.Mo C_x supported Pt-Cu bimetallic nanocrystals were prepared by a liquid phase method.The effects of support and composition on the catalytic performance of the catalyst were investigated.Compared with commercial Pt/C,the catalyst showed excellent hydrogen evolution activity and stability.This strategy provides a new way to synthesize other metal supported catalysts.（3）Based on the fact that the support affects the HER performance of Pt-based catalysts,the carbon nanofibers with high corrosion resistance is selected as the support and ZIF-67 is used as the precursor.Nitrogen-doped carbon nanofibers with porous structure were obtained by electrospinning and two-stage calcinations process.And the N-doped carbon nanofibers loaded with Pt-Cu bimetallic nanocrystals were prepared by a simple liquid phase method.The effect of N-doped carbon nanofibers on the electronic structure and surface structure of the composite were also investigated.The results show that Pt-Cu bimetallic nanocrystals loaded on the nitrogen-doped carbon nanofibers has excellent electrocatalytic performance and stability,and the hydrogen evolution reaction activity is obviously higher than that of most of the reported catalysts.