Preparation Of Structurally Ordered Intermetallic Pt₃Co Nanowires And Research On Electrocatalytic Performance

Nowadays,the global ecology and environment are evidently affected by the over-exploitation traditional energy and pollution.Developing new energy conversion technologies has become a far-reaching task.Among them,the slow kinetic oxygen reduction reaction(ORR)at the cathode of fuel cells and the strong adsorption of CO on the surface of catalyst are impairing overall efficiency.Therefore,the design of new and efficient electrocatalysts with lasting resistance to CO poisoning has become a hot topic.At present,commercial catalysts for ORR are Pt/C particles,but there are two unavoidable shortcomings.First,Pt/C tends to absorb small molecules such as-OH or CO.Second,Pt/C particles lack long-term stability because they are inclined to agglomerate.To solve them and improve catalytic efficiency,this project attempted to introduce Co as a second transition metal into the Pt crystal lattice to dissociate oxygen reduction intermediates or small CO molecules.At the same time,nanowires alloy with stable one-dimensional structure was designed to retard the maturation,aggregation and shedding of the catalyst.In order to achieve high precision of synthetic materials and the most efficient use of platinum,anode alumina template(AAO)was used for potentiostatic deposition.Chloroplatinic acid hexahydrate was used as the source of platinum,and cobalt sulfate heptahydrate as the source of cobalt.Deposition potential in a certain concentration of the solution was regulated to figure out the proportion of the alloy,and Pt₃Co-Green alloy nanowires have been synthesized in the condition of-0.4 V(vs.SCE).Then,the alloy nanowires have been annealed at high temperature in vacuum,and transformed into“Pt₃Co-Disorder”at 400?and“Pt₃Co-Ordered”at 650?.Their structural characterization has proved that they had achieved ordering transformation.After dissolution in the mixture of phosphoric acid and chromic acid,the alloy nanowires were released from AAO and used to test the electrocatalytic oxygen reduction reaction and CO poisoning resistance.As expected,compared to disorder Pt₃Co nanowires and commercial Pt/C particles,ordered Pt₃Co nanowires have shown better half-wave potential and mass activity,confirming the advantages of ordered Pt₃Co nanowires in elemental distribution and lattice structure.In addition,ordered and disordered Pt₃Co nanowires still had better activity than Pt/C particles after 5000 durability tests.In the CO poisoning resistance test,ordered Pt₃Co nanowires exhibited better capacity in long-term CO dissociation due to its stable structure.The loss of oxygen reduction activity before and after the poisoning experiment was minimized.It can be seen that ordered Pt₃Co nanowires,as a type of acceptable material for catalyst with commercial value,have become an alternative material for future fuel cell catalysts.