Preparation Of Platinum-nickelaurum Ternary Alloy Catalysts And Their Oxygen Reduction Reaction

Oxygen reduction reaction(ORR)is one of the most important reactions in fuel cells.Due to the high electrocatalytic activity of Pt nanoparticles,a wide number of catalysts have been produced that have proven to be better than commercial Pt/C,and many of them have surpassed the DOE targets.Thus,Ptbased catalysts have become an integral part of PEMFC.However,due to the high cost of Pt and the limited reserves of Pt on the earth,we have to reduce the usage of Pt and improve the utilization rate of Pt and the activity of the catalyst.With the increase in pollution in recent years,PEMFCs have received a lot of attention,but the high cost of the Pt-based catalyst has prevented PEMFCs from being widely used.Nowadays,the most effective way to improve the catalyst performance and reduce the usage of Pt is to alloying transition metal with Pt.The high openness structure of the catalyst is enhanced by adjusting the synthesis method,particle size,and morphology of nanoparticles,to improve the atomic utilization of Pt.Although the binary catalysts effectively reduce the poisoning effect of CO,they are prone to dissolution into the strongly acidic medium of the working electrolytes,leading to structural reconstruction and impaired catalyst performance.Incorporating a third non-noble metal has improved the synergy between the metals and increased the catalyst’s lifetime under working conditions.Therefore,in this study,Pt was alloyed with Ni and Au to obtain more efficient ternary alloy nanomaterials.The specific research contents are as follows:(1)To reduce the cost of catalyst and the consumption of Pt,Au@PtNiAu concave octahedral core-shell catalyst(Au@PtNiAu-COCS)was synthesized by one-step solvothermal method and acid etching method.As the intermediate of Au@PtNiAu concave octahedral core-shell catalyst(Au@PtNiAu-COCS),the growth of Au@PtNiAu-OCS can be well controlled by adjusting the amount of CTAC,precursor,and reaction temperature.The final catalyst Au@PtNiAuCOCS was obtained by acid etching.The shell of Au@PtNiAu-COCS is Pt rich,which promotes the improvement of the atomic utilization rate of Pt.The halfwave potential reaches 0.948 V,and the oxygen reduction reaction(ORR)mass activity reaches 11.22 times that of commercial Pt/C.The mass activity of methanol oxidation reaction(MOR)was 4.56 times that of commercial Pt/C.The power density and current density in the membrane electrode assembly(MEA)are higher than Pt/C.This work provides effective ideas and methods for Pt-based catalysts and the synthesis of core-shell nanostructures.(2)To improve the catalytic performance of Pt-based catalysts for ORR and reduce the consumption of Pt,we have synthesized PtNiAu octahedral nanoframe(NF)in one step by solvothermal method.Solid nanocrystals can be obtained by adjusting the Pt precursor and structure-directing agent selection.Based on the formation mechanism of binary nanoframe,we studied the growth mechanism and morphological evolution of the ternary nanoframe.Nano-framed catalysts show superior mass activity and durability in the oxygen reduction reaction.This study provides more possibilities to prepare high-performance alloy nanocatalysts in the future.