Study On Fabrication Of Palladium Nano-alloy Catalyst And Its Electrocatalytic Performance Of Alcohol Oxidation

The important challenge facing society at present is how to deal with the ever-increasing energy demand and environmental degradation.Direct alcohol fuel cells can effectively convert chemical energy into electrical energy by using catalysts,and have received widespread attention as a clean energy device.However,the development of alcohol fuel cells is restricted by the slow reaction kinetics of the anode alcohol reaction and the metal platinum catalyst is easily poisoned and deactivated.Therefore,the preparation of high-efficiency,durable,and platinum-replaceable electrocatalysts is great significance to the development of direct alcohol fuel cells.Pd has always been regarded as an economic substitute for Pt due to its abundant reserves and higher cost-effectiveness.However,it still has the shortcomings of insufficient activity and poor durability.Hitherto,the improvement of catalytic performance can start from two aspects:on the one hand,the introduction of other metal alloys,and the use of electronic interaction or synergistic effect with Pd to achieve the purpose of improving the catalytic behavior;on the other hand,the morphology of nanomaterials is adjusted to expose more active sites.The strong electronic effects between the metal components of the nano-alloy can improve the adsorption strength of reactant molecules on its surface,thereby affecting the essential catalytic properties of the metal nano-alloy catalyst.In addition,alloying noble metal components（such as Pt and Pd）can also effectively reduce the content of precious metal active components in the catalyst and reduce the preparation cost of the catalyst.Therefore,this article aims to improve the performance of the catalyst and improve the stability of the catalyst.Through different chemical methods,a series of metal Pd nano-alloy catalysts are designed and adjusted,and the catalytic behavior of electrocatalytic oxidation of small alcohols in alkaline medium is explored.The research content is as follows:（1）Prepare PdCu hollow octahedral catalyst with Cu₂O as a template,and then remove the template in a relatively mild environment conditions（under atmospheric pressure and at room temperature）.In the electrochemical test,the PdCu hollow octahedral catalyst exhibited excellent catalytic activity,and its mass activity was 2020.1 m A/mg _Pd,which was about twice that of commercial Pt/C.In addition,in terms of stability testing,the performance of PdCu hollow octahedrons is also higher than that of commercial Pt/C.SEM and TEM characterization methods show that the prepared PdCu catalyst has a hollow porous structure,which can provide more active sites to catalyze the ethanol oxidation reaction（EOR）.XPS test results show that the introduction of Cu atoms can effectively modify the electronic structure of Pd,weaken the adsorption strength of Pd atoms and reaction intermediates,facilitate its oxidation removal,and improve the electrochemical activity and stability of the catalyst.（2）A series of Pd Ag alloy catalysts with different atomic ratios were prepared by solvothermal method.Studies have shown that the introduction of metal Ag promotes the formation of OH_ads,thereby accelerating the oxidative removal of reaction intermediates,cleaning the active sites on the Pd surface,and making the catalyst have excellent EOR activity.In addition,when the Pd/Ag atomic ratio is 1/1,the catalyst exhibits the highest activity(1934.0 m A/mg _Pd)and strong stability（the mass specific activity only drops 58%after the 500 CV test）.（3）The CuPdRu alloy catalyst is prepared by using the oil bath method.The electrochemical test results show that the Cu Pd Ru alloy catalyst exhibits high activity for electrocatalytic oxidation of monoalcohol in alkaline medium,and its highest mass specific activity is 6188.9 m A/mg _Pd.In addition,it also exhibits better catalytic activity and superior electrochemical stability in the electrocatalytic oxidation of polyols.In the oxidation reaction of glycerol,its mass specific activity is 4.5 times that of commercial Pt/C.After a six-hour chronoamperometry test,it can still maintain a high reaction activity.Studies have shown that there are strong electronic effects and more optimized synergistic effects in the three metals of Cu,Pd,and Ru,which can improve the poison resistance and electrochemical activity of the catalyst.This work demonstrates the potential application and importance of the composition and morphology engineering of catalyst nanostructures in electrocatalysis.