Based On Construct Bimetallic Core-Shell Structure For Improve Hydrogen Evolution Reaction Performance

Hydrogen energy,as clean and renewable energy,is regarded as ideal energy.Thanks to the features of environmentally friendly,high purity and abundant raw materials,large-scale hydrogen production via electrochemical water splitting has gradually become the promising way.To improve hydrogen evolution reaction performance,noble metal materials with high catalytic activity has been a hot area of research for years.The design and development of novel support and multimetallic systems?e.g.core-shell structure,bimetallic alloys etc.?also important for made significant contributions to the field.In this paper,the synthesis part discusses numerous synthetic strategy for mesoporous SiO₂-based loading noble metal NPs and monometallic or bimetallic core-shell structure nanospheres,along with their applications in electrocatalytic HER.The morphology,composition and structure of composites were characterized by SEM,TEM,XRD and XPS etc.The findings could provide theoretical supports for manufacture process of new type HER catalysts.The main research achievements are as follows:1.Mesoporous Au@SiO₂ NPs has been successfully fabricated by a facile hydrothermal and Stober method.TEM and BET analysis showed the controlable pore diameter?6?9 nm?of mesoporous SiO₂ and Au NPs disperse on its surface without aggregation.Electrocatalytic activities of the samples for hydrogen evolution were investigated by active area and HER rate.2.Core-shell structured Au@SiO₂,Pt@SiO₂ and Ag@SiO₂ nanospheres were obtained by traditional soft-template method.TEM imagings of samples revealed the formation of big Au NPs?d = 18±3 nm?,middle Ag NPs?d = 10±2 nm?and small Pt NPs?d = 2±1 nm?in/on SiO₂ nanospheres.The single core nanosphere revealed the liquid-phase stabilized material?CTAB?containing metallic NPs is expected to promote NPs dispersed isolation within a space of a few tens of nanometers.The electrochemical results showed that Pt@SiO₂ nanospheres exhibited good electrocatalytic HER performance:low initial potential and overpotential?10 mA?,low Tafel slope and high electrochemically active surface area.By comparison,the catalytic activity of Pt@SiO₂ nanospheres was superior to Pt@SiO₂ nanosheets with same Pt amount which attributed to the importance of favorable dispersibility.3.Core@shell structure strategy was used to fabricate bimetallic core-shell structure nanospheres Au@SiO₂-Pt.CTAB and TEOS are utilized to hinder the agglomeration of Au NPs or Pt NPs.At the same time,TEOS containing metallic NPs is expected to promote Pt NPs dispersed isolation within SiO₂ nanospheres.TEM images show the unique bimetallic core-shell structure:a single Au NPs as a core and mesoporous silica decorated with Pt NPs as a shell.Investigation of electrocatalytic activities of Au@SiO₂-Pt by the HER revealed that the Au@SiO₂-Pt exhibits a low Tafel slope of 52 mV/dec,and its catalytic activity being maintained for at least 10 h.Impressively,it also demonstrates a high turnover frequency?TOF?value of 0.11s-1.Systematic investigation suggests that Au core providing unique conductive ability for the electrons.The entire hydrogen evolution process of Pt NPs through strong electrostatic attraction,in a tight H3O+ packing accordingly increased the adsorbed hydrogen?Had?rate.4.Au@SiO₂-Ag nanospheres were also successfully fabricated.Samples were characterized by XRD,TEM,HRTEM,TEM-mapping,XPS and also analysised the electrochemical properties of hydrogen evolution reaction.TEM imaging of samples revealed the diameter of Au@SiO₂-Ag?-60 nm?.SiO₂ nanosphere encapsulated Au NPs and Ag NPs without agglomeration.The preparation of Au@SiO₂-Ag demonstrated that the way suit for synthesis other mulit-metallic core-shell structure nanospheres.The method allows different combinations of starting materials to construct a series core-satellite-shell structured nanocomposite for improve HER performance.