Study On Surface Morphology And Surface Compression Strain Behavior Of PtCu Catalyst

Due to the merits of higher catalytic properties and stability for Pt-based catalysts, it is widely employed in each profession and domain, such as fuel cells, car exhausts purification, petrochemical engineering and biological carrier. However, as a Pt/C electro-catalyst, a higher material cost makes it unable to be intensively applied in industrial and commercial. A crux way to reduce costs is to cut down Pt loadings for a Pt-based catalyst, boost the utilization rate of Pt and not to have a negative impact on catalytic performance for a Pt-based catalyst simultaneously. In consequence, to develop a Pt-based alloy catalyst with a low Pt loading and high catalytic activity is a research highlight in the domain of fuel cells for domestic and overseas research scholars.For this study, PtCu/C alloy catalysts with the Cu-doped content of 36.10wt.% are synthesized by Ion Beam Sputtering (IBS) techniques, followed by annealed at 400℃ in vacuum and then electrochemically etched for different times using three methods of Potentiostatic corrosion (PC), Ultrasonic Potentiostatic corrosion (UPC) and Ultrasonic Cyclic Voltammetry corrosion (UCV). The evaluation results of CV, LSV and ICP-AES show that UCV is an optimal modification one in such three electrochemical etching methods. UCV not only can enhance its catalytic performance and electrochemically active specific surface area, but also reduce etching time, decrease Pt wastage rate during corrosion and lower the energy consumption of hydrogen evolution. The exchange current density k of the sample that is electrochemically modified for 2.5h by UCV in the 0.5mol/L H2SO4 aqueous solution is the best, up to 0.005903A·cm-2. Compared with a Pt/C, its catalytic performance is enhanced by approximately 51.32%, the active specific surface area ESA is increased by 92.32% and Pt loadings is reduced by about 34.91%. The sample that is modified by UCV embodies the characteristic of lower Pt loading capacity and higher catalytic properties. The analysis results of STEM&EDS reveal that a particle on the surface of the performance-optimal sample by UCV possesses a kind of PtCu@Pt core@shell structure, vastly boosting Pt utilization. The compressive strain on the surface of PtCu@Pt core-shell particles is further detected by TEM, which alter its electron cloud density and improve the performance of thin film. Ultimately, the electronic structure effect of compressive strain is further probed by XPS characterization.