Study On Electrocatalytic Oxidation Of Alcohol Of Multi-component Noble Metal-based Catalysts Prepared By Phosphating-Dealloying

In recent years,catalysts have played an important role in the design of alcohol fuel cells and received extensive attention.Pt or Pd-based noble metal materials conventionally used as anode catalysts have problems such as low service life,high manufacturing cost,and poor stability,which severely restrict the commercial application in alcohol fuel cells.Therefore,designing novel methods to obtain high-performance catalysts is the most effective way for the development of fuel cell technology.As an effective method to improve the performance of traditional noble metal-based catalysts,dealloying is to remove more active metals from the surface of the multi-component nano-alloy and obtain the desired structure of the noble metal surface,which is beneficial as an effective strategy of improving the performance of electrocatalytic reactions.At the same time,non-metallic phosphorus has rich valence electrons,which can affect the electronic state of its composite metal alloys.Especially it has a significant promotion effect on the improvement of the catalytic performance of precious metals.At present,many studies have confirmed that the catalytic activity,stability and other aspects have significantly improved the catalytic performance of precious metals.In view of this,if a multicomponent metal alloy nanoparticle precursor with noble metal as the main component is first prepared,followed by acid dealloying treatment and finally high-temperature phosphating treatment,the performance of the noble metal-based catalyst may be promoted.Through the method of phosphating and dealloying,the three components of "noble metal-auxiliary metal-nonmetal" in a catalyst are finally achieved,and it shows high stability and high activity.In this paper,the goal is designing a low-cost and high-performance multi-component precious metal-based composite electrocatalyst.The three components of "noble metal-auxiliary metal-nonmetal" have been prepared by phosphating-dealloying method,which applied to the ethylene glycol oxidation reaction and glycerol oxidation reaction.Firstly,the electrocatalytic performance of D-Pt Pd Cox/PMC catalyst prepared by dealloying with high Pt Pd content in the ethylene glycol oxidation was investigated.Based on this method,the dealloying noble metal Pt-based precursor(D-Pt Cox/C)were phosphatized with Na H2PO2 at 300 °C to obtain P-(D-Pt Cox)/C catalyst,which applied in ethylene glycol oxidation.Finally,the universality of the phosphating-dealloying method was verified and expanded.The Pd-based multi-component P-D-Pd Cox/C was prepared,and studied its catalytic performance for glycerol oxidation.The main research content and results are specifically the following three parts:Part One: Dealloying Co-rich PtPdCo nanoparticles on nitrogen modified carbon as advanced electrocatalyst for ethylene glycol oxidationIn order to improve the catalytic performance of noble metal catalysts and utilization of precious metals,in this part,a high Co content Pt Pd Cox(x = 4~8)precursor is supported on 1,10-phenanthroline modified carbon support,and then a series of D-Pt Pd Cox/PMC catalysts were prepared by dealloying.Electrochemical test results show that in as-prepared samples,the electrochemical active specific surface area(EASA)of D-Pt Pd Co7/PMC electrocatalyst is as high as 1748.7 cm-2 mg-1Pt Pd,which is 3.23 times that of commercial Pt/C,and the current density is 0.0632 A mg-1Pt Pd after the 3000 s test,which has good electrocatalytic activity and good electrocatalytic stability for ethylene glycol oxidation.TEM characterization results show that the particle size of the metal nanoparticles is only 3.9±0.9 nm.This method reduces the size of the loaded metal nanoparticles and disperses uniformly,which is beneficial to expose more active sites.The study laid the foundation for the subsequent preparation of noble metal-based multi-component catalysts.Part Two: Phosphating-dealloying Co-rich Pt Co used in electrocatalytic oxidation of ethylene glycolIn this section,the precursors of Pt Co nanoparticles with high cobalt content on carbon support were prepared,and then dealloying with HCl.The resulting samples were mixed with Na H2PO2 at 300 ? for phosphating,and finally a series of electrocatalysts were obtained(P-(D-Pt Cox)/C,x = 2,4,6,8).TEM results show that the obtained phosphating-dealloying nanoparticles are evenly distributed on the surface of the carbon support with the particle size of 1.9±0.5 nm.Electrochemical test results show that compared with P-(D-Pt)/C,P-(D-Pt Co4)/C has high ethylene glycol current density(322.8 m A mg-1Pt),and the current after 3000 s test is 0.26 m A mg-1Pt,which show that ia exhibites good ethylene glycol oxidation performance and stability.The phosphating-dealloying strategy is developed in this research,which provides new ideas for the preparation of high-performance multi-component noble metal-based catalysts.Part Three: Enhanced electrocatalytic glycerol electrocatalytic oxidation performance on phosphating-dealloying Co-rich Pd CoTo verify the universality of the aforementioned phosphating-dealloying method for preparing multi-component "noble metal-auxiliary metal-nonmetal" materials,this part is further expanded and verified on Pd-based catalysts.P-D-Pd Cox/C(x = 1,3,5,7)electrocatalyst was successfully prepared by phosphating-dealloying and glycerol electrooxidation performance was studied.Physical characterization shows that the particle size of P-D-Pd Co3/C is 4.8±1.5 nm.Electrochemical test results show that it has the highest peak current density of(65.9 m A mg-1Pd).The current density after 3000 s is 0.48 m A mg-1Pd,which is higher than other P-D-Pd Co/C,P-D-Pd Co5/C,P-D-Pd Co7/C and P-D-Pd/C electrocatalysts.The results show that P-D-Pd Co3/C exhibits good glycerol electrocatalytic activity and good stability.The study shows that the phosphating-dealloying method has good development prospects in the preparation of multi-component precious metal-based catalysts.