title: A Janus cobalt-based catalytic material for electro-splitting of water.
abstract: The future of energy supply depends on innovative breakthroughs regarding the design of cheap, sustainable and efficient systems for the conversion and storage of renewable energy sources. The production of hydrogen through water splitting seems a promising and appealing solution. We found that a robust nanoparticulate electrocatalytic material, H(2)-CoCat, can be electrochemically prepared from cobalt salts in a phosphate buffer. This material consists of metallic cobalt coated with a cobalt-oxo/hydroxo-phosphate layer in contact with the electrolyte and mediates H(2) evolution from neutral aqueous buffer at modest overpotentials. Remarkably, it can be converted on anodic equilibration into the previously described amorphous cobalt oxide film (O(2)-CoCat or CoPi) catalysing O(2) evolution. The switch between the two catalytic forms is fully reversible and corresponds to a local interconversion between two morphologies and compositions at the surface of the electrode. After deposition, the noble-metal-free coating thus functions as a robust, bifunctional and switchable catalyst.
authors.affiliation: Laboratoire de Chimie et Biologie des Métaux (CEA/Université Grenoble 1/CNRS), 17 rue des Martyrs, 38054 Grenoble cedex 09, France.
authors.forename: Saioa
authors.initials: S
authors.lastname: Cobo
authors.forename: Jonathan
authors.initials: J
authors.lastname: Heidkamp
authors.forename: Pierre-André
authors.initials: PA
authors.lastname: Jacques
authors.forename: Jennifer
authors.initials: J
authors.lastname: Fize
authors.forename: Vincent
authors.initials: V
authors.lastname: Fourmond
authors.forename: Laure
authors.initials: L
authors.lastname: Guetaz
authors.forename: Bruno
authors.initials: B
authors.lastname: Jousselme
authors.forename: Valentina
authors.initials: V
authors.lastname: Ivanova
authors.forename: Holger
authors.initials: H
authors.lastname: Dau
authors.forename: Serge
authors.initials: S
authors.lastname: Palacin
authors.forename: Marc
authors.initials: M
authors.lastname: Fontecave
authors.forename: Vincent
authors.initials: V
authors.lastname: Artero