Abstract
Alloys of platinum and lanthanides present a remarkable activity for the oxygen reduction reaction—both in the form of extended surfaces and nanoparticulate catalysts. Co-sputter-deposited thin film catalysts based on platinum and gadolinium show great oxygen reduction activity improvement over pure Pt. The sputter-deposition technique represents a viable and versatile approach for investigating model catalyst systems with different compositions. In this work, co-sputtered Pt5Gd and Pt7.5Gd thin films were investigated using X-ray absorption spectroscopy as well as standardized electrochemical techniques. These investigations revealed the importance of forming alloys with specific stoichiometry, supporting the need of forming compressively strained Pt overlayers in order to achieve optimum catalytic performances.
Highlights
Hydrogen-fueled energy conversion devices such as low-temperature fuel cells are expected to play a key role in the transition towards a sustainable economy [1]
Ptx Gd thin films were produced by means of co-sputtering Pt and Gd [37]
To investigate the of the Pt overlayers, ex situ X-ray absorption spectroscopy (XAS) was employed on 10-nm-thick Ptx Gd samples, both as-prepared and structure of the Pt overlayers, situHClO
Summary
Hydrogen-fueled energy conversion devices such as low-temperature fuel cells are expected to play a key role in the transition towards a sustainable economy [1]. The ORR activity on Pt-based catalysts follows a Sabatier volcano relationship with the binding energy of the oxygen-containing reaction intermediates, e.g., OH This has been thoroughly corroborated from extensive density functional theory (DFT) calculations [12,13]. A key understanding of the structure of the active phase from our work on extended Pt–lanthanide alloys enabled the design and development of nanoparticulate Pt–Gd catalysts in the form nanoparticles [21] and thin films [37], both exhibiting enhanced ORR activity over pure. Investigating Pt–Gd ratios that will lead to a compressive strain of the Pt overlayer that allow the desirable weakening of the OH binding energy would be key to design and develop Pt–Gd catalysts exhibiting optimum values of both ORR activity and stability. Tested samples were studied using X-ray absorption spectroscopy (XAS)
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