The Surface/interface Engineering Of Pt-Based Catalysts By Sn/Rh/Au And Their Performance For The Electrooxidation And Hydrogen Evolution Reaction

Pt-containing solid nanomaterials are widely used as catalysts in the field of electrocatalysis.However,the high cost and scarcity Pt create a grand obstacle on the expansibility of Pt-containing electrocatalysts in commercial application.Many researches have been devoted to optimize the surface properties of Pt-based nanomaterials arising from the strong relationship between the surface/interface properties and electrocatalytic properties of electrocatalyst,thus enhancing the catalytic performance of electrocatalysts and reducing the waste of Pt.Combining Pt with other metal to form binary alloy have been considered to be an effective strategy to regulate the catalytic performance of catalyst towards the electro-oxidation of small organic molecules.However,binary alloys have an issue of the insufficient synergy between the Pt component and foreign metal.In addition,the high activity binary alloy catalysts,such as the catalysts exposed by high-index facets,face the problem of the degradation of catalytic activity due to the dissolution and rearrangement of surface structure during the reaction process.In this paper,the third metal Sn or Rh as the “active auxiliaries” is introduced into the surface of Pt-based alloy to regulate the surface composition and stabilize the surface structure of the catalyst,enhancing the catalytic activity,stability and CO anti-poisoning for the electro-oxidation of small organic molecules.Additionally,considering the activity degradation induced by the carbon corrosion during the process of hydrogen evolution reaction for a carbonsupported Pt catalyst,we also attempt to improve the catalytic activity and stability of Pt for hydrogen evolution reaction by introducing the Au supported Pt active entity.The research content and conclusion of this paper are as follows.1.The strategy of two-step hydrothermal reduction was adopted to implant the oxyphilic metal into the surface of high-indexed Pt3 Mn concave nanocrystals to optimize the surface electronic structure of Pt and stabilize the surface structure,thus enhancing the catalytic activity,stability as well as anti-poisoning for methanol(MOR)and formic acid(FAOR)of electrooxidation.The results of X-ray photoelectron spectroscopy(XPS),Transmission electron microscope(TEM)and X-ray powder diffraction(XRD)indicate that the implantation of Sn can regulate the electronic properties of Pt,and the Sn-modified Pt3 Mn catalyst maintains the high-indexed surface structure.The results of activity measurement show that the introduction of Sn can effectively improve the electrocatalytic activity of MOR and FAOR.And the activity presents a volcano-shaped correlation with the amount of Sn.The stability test shows that the implantation of appropriate Sn to decorate Pt3 Mn is conducive to preserve the surface structure during reaction process,improving the stability and activity of catalyst.Moreover,the implantation of moderate Sn can significantly enhance the oxidation ability of CO,improving the anti-poisoning ability.The studies of thermodynamics and kinetic also suggest that the Sn-doped catalysts have the advantage in promoting charge transfer and decreasing the reaction activation energy.This work can provide a strategy to the design of high-indexed Pt-based catalyst with best catalytic activity and stability.2.Considering the special surface structure properties of high-indexed nanocrystals,a two-step hydrothermal reduction method was adopted to construct the Ptm^Au TOH(m: atomic ratio of Pt and Au)bimetallic catalyst by introducing smaller Pt “active entity”(1.74 nm)onto the surface of high-indexed Au TOH to explore the effects of high-indexed Au underlying and its smaller Pt carriers catalytic for catalytic performance of HER.The analysis of TEM,XPS and XRD show that Pt particles were successfully loaded on the high-index Au TOH.The catalytic performance of HER is related to the amount of Pt “active entity” on the underlying Au.When the amount of Pt “active entity” is lower,the Pt entities exhibit more independence character on the Au TOH,which is more conducive to maximum utilization of Pt and charge transfer,achieving the better activity and stability.Besides,this Pt-on-Au structure also performs an increasing in activity of EGOR,further providing the design strategy for multifunctional catalyst.3.The Rh-modified Pt-Ni alloy nanowire bundles(Rh PtNi-NWBs)were constructed by introducing highly oxophilic Rh metal as an active modifier or structural stabilizer into the surface of 1D Pt-Ni NWBs to optimize the catalytic performance of electrocatalyst for the electrooxidation of ethanol(EOR).The analysis of TEM,XRD and XPS show that the implantation of Rh can induce the lattice strain of Pt and promote the redistribution and transportation of electrons from other metal to Pt.Incorporating the highly oxophilic Rh with the 1D Pt-Ni alloy structure can significantly enhance the catalytic activity and stability for EOR.The Rh0.05Pt85.6Ni14.4-NWBs with lower Rh content shows the optimal activity and stability.The stability study shows that the implantation of Rh is conducive to the maintenance of the initial crystal structure of the catalyst during the reaction process.The study of in-situ Fourier transform infrared spectroscopy(in situ FTIR)reveals that Rhincorporated PtNi NWBs can influence the path way of EOR,which is beneficial for the C-C bond cleavage of ethanol and removal of adsorbed CO intermediate at low potential.