title: Suppression of Photoanodic Surface Oxidation of n-Type 6H-SiC Electrodes in Aqueous Electrolytes.
abstract: The photoelectrochemical characterization of silicon carbide (SiC) electrodes is important for enabling a wide range of potential applications for this semiconductor. However, photocorrosion of the SiC surface remains a key challenge, because this process considerably hinders the deployment of this material into functional devices. In this report, we use cyclic voltammetry to investigate the stability of n-type 6H-SiC photoelectrodes in buffered aqueous electrolytes. For measurements in pure Tris buffer, photogenerated holes accumulate at the interface under anodic polarization, resulting in the formation of a porous surface oxide layer. Two possibilities are presented to significantly enhance the stability of the SiC photoelectrodes. In the first approach, redox molecules are added to the buffer solution to kinetically facilitate hole transfer to these molecules, and in the second approach, water oxidation in the electrolyte is induced by depositing a cobalt phosphate catalyst onto the semiconductor surface. Both methods are found to effectively suppress photocorrosion of the SiC electrodes, as confirmed by atomic force microscopy and X-ray photoelectron spectroscopy measurements. The presented study provides straightforward routes to stabilize n-type SiC photoelectrodes in aqueous electrolytes, which is essential for a possible utilization of this material in the fields of photocatalysis and multimodal biosensing.
authors.affiliation: Walter Schottky Institut and Physik-Department, Technische Universität München , Am Coulombwall 4, 85748 Garching, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Sachsenhauser
authors.affiliation: Joint Center for Artificial Photosynthesis, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.|Chemical Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.
authors.forename: Karl
authors.initials: K
authors.lastname: Walczak
authors.affiliation: Walter Schottky Institut and Physik-Department, Technische Universität München , Am Coulombwall 4, 85748 Garching, Germany.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Hampel
authors.affiliation: Walter Schottky Institut and Physik-Department, Technische Universität München , Am Coulombwall 4, 85748 Garching, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Stutzmann
authors.affiliation: Joint Center for Artificial Photosynthesis, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.|Chemical Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.
authors.forename: Ian D
authors.initials: ID
authors.lastname: Sharp
authors.affiliation: Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and The Barcelona Institute of Science and Technology , Campus UAB, Bellaterra, 08193 Barcelona, Spain.|ICREA, Institució Catalana de Recerca i Estudis Avançats , 08070 Barcelona, Spain.
authors.forename: Jose A
authors.initials: JA
authors.lastname: Garrido
mesh_terms: D017554:Carbon Compounds, Inorganic / Q000737:chemistry / Q000528:radiation effects*; D002384:Catalysis; D003035:Cobalt / Q000737:chemistry; D055664:Electrochemical Techniques; D004566:Electrodes; D005295:Ferrocyanides / Q000737:chemistry; D006859:Hydrogen / Q000737:chemistry; D006873:Hydroquinones / Q000737:chemistry; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry; D010710:Phosphates / Q000737:chemistry; D017655:Silicon Compounds / Q000737:chemistry / Q000528:radiation effects*; D014325:Tromethamine; D014466:Ultraviolet Rays; D014867:Water / Q000737:chemistry
chemical_list: D017554:Carbon Compounds, Inorganic; D005295:Ferrocyanides; D006873:Hydroquinones; D010710:Phosphates; D017655:Silicon Compounds; D014325:Tromethamine; D014867:Water; D003035:Cobalt; D006859:Hydrogen; C031835:potassium ferrocyanide; D010100:Oxygen; C022088:silicon carbide; C031927:hydroquinone