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The role of synthesis conditions for structural defects and lattice strain in beta-TaON and their effect on photo- and photoelectrocatalysis

Rohloff, Martin; Cosgun, Sevilay; Massue, Cyriac; Lunkenbein, Thomas; Senyshyn, Anatoliy; Lerch, Martin; Fischer, Anna; Behrens, Malte

FG Anorganische Chemie - Festkörper- und Materialchemie

The importance of the synthesis conditions on the structural and photocatalytic properties of tantalum oxide nitride was investigated by comparing two variants of phase-pure β-TaON obtained from application of two different synthesis routes, leading to one unstrained and one heavily anisotropically microstrained β-TaON as shown by XRD-based Rietveld refinement. HRTEM images reveal the origin of the strain to be lattice defects such as stacking faults. The strained β-TaON was found to be the clearly less active semiconductor in photochemical and photoelectrochemical water oxidation. The lattice defects are assumed to act as charge carrier traps hindering the photo-generated holes to be displaced to the reaction sites at the surface.