Electrochemical Desorption of Thiolates and Sulfur from Planar and Nanoparticle Platinum Surfaces

MARÍA ALEJANDRA FLORIDIA ADDATO; ALDO RUBERT; GUILLERMO BENÍTEZ; EUGENIA ZELAYA; GEMA CABELLO; ANGEL CUESTA; JORGE E. THOMAS; ARNALDO VISINTÍN; ROBERTO C. SALVAREZZA; MARIANO H. FONTICELLI

JOURNAL OF PHYSICAL CHEMISTRY C

AMER CHEMICAL SOC

Lugar: Washington; Año: 2013 p. 7589 - 7597

1932-7447

Thiolate-protected metal nanoparticles are one of the most studied systems in nanotechnology because these capping agents allow the preparation of monodisperse nanoparticles with controlled sizes and electronic properties. In particular, thiolate-protected platinum nanoparticles (PtNPs) became promising for applications in heterogeneous catalysis and the fabrication of new materials for hydrogen storage, although thiol removal might be required before its use, once the nanoparticles have been conveniently grafted onto a particular support. Here, thiolate and sulfur electrodesorption from planar and nanoparticle platinum surfaces is studied by combining ex situ X-ray photoelectron spectroscopy (XPS) and electrochemical techniques. Our results show that a complete removal of short thiols can be performed by reductive stripping at very negative potentials, well within the hydrogen evolution reaction region, the amount of thiolates or sulfur remaining on the electrode surface after this treatment being below the detection limit for both planar surfaces and carbon-supported Pt nanoparticles. Our results also demonstrate that reductive stripping is a simple way to clean short chain thiol-capped PtNPs supported on conducting substrates. Finally, the addition of thiomalic acid-protected PtNPs improved the performance of a hydrogen storage alloy material, with no additional steps in the preparation of the electrodes.