Beschreibung:
Zusammenfassung: A mild screen-printing method was developed to coat conductive oxide surfaces (FTO) with μm-thick layers of pre-synthesised calcium manganese oxide (Ca-birnessite) particles. After optimization steps concerning printing process and layer thickness, electrodes were obtained which can be used as corrosion-stable water-oxidizing anodes at pH7 yielding current densities of 1mA·cm-2 at an overpotential of less than 500mV. Analyses of electrode coatings of optimal thickness (~10μm) indicated that composition, oxide phase and morphology of the synthetic Ca-birnessite particles are hardly affected by the screen-printing procedure. However, a more detailed analysis by X-ray absorption spectroscopy revealed small modifications of both Mn redox state and structure at the atomic level which could affect functional properties like proton conductivity.Furthermore, the versatile new screen-printing method was used for a comparative study of various transition metal oxides concerning electrochemical water oxidation at “artificial leaf conditions” (neutral pH, fairly low η and i), where a general activity ranking RuO2 > Co3O4~(Ca)MnOx~NiO was observed. Within the group of screened manganese oxides, Ca-birnessite performed better than “Mn-only materials” like Mn2O3 or MnO2