Photocatalytic properties of CoOx-loaded nano-crystalline perovskite oxynitrides ABO2N (A = Ca, Sr, Ba, La; B = Nb, Ta)

•Ta- and Nb-based oxynitrides were obtained from hydrothermally prepared precursors.•After ammonolysis phase pure samples with large specific surfaces were achieved.•Morphological, optical and thermal properties were investigated.•Loading with CoOx was successfully applied to enhance photocatalytic activities.•CaNbO2N and SrNbO2N showed high photocatalytic activities for dye degradation.

Highly crystalline niobium- and tantalum-based oxynitride perovskite nanoparticles were obtained from hydrothermally synthesized oxide precursors by thermal ammonolysis at different temperatures. The samples were studied with respect to their morphological, optical and thermal properties as well as their photocatalytic activity in the decomposition of methyl orange. Phase pure oxynitrides were obtained at rather low ammonolysis temperatures between 740 °C (CaNbO2N) and 1000 °C (BaTaO2N). Particle sizes were found to be in the range 27 nm–146 nm and large specific surface areas up to 37 m2 g−1 were observed. High photocatalytic activities were found for CaNbO2N and SrNbO2N prepared at low ammonolysis temperatures. CoOx as co-catalyst was loaded on the oxynitride particles resulting in a strong increase of the photocatalytic activities up to 30% methyl orange degradation within 3 h for SrNbO2N:CoOx.

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