Novel UV Sensing and Photocatalytic Properties of DyCoO3

Oxides with the perovskite type structure of formula LnCoO(3), where Ln is a rare earth element, have unique physical and chemical properties. These materials are applied in catalysis, gas sensors, and electrodes for solid oxide fuel cells, among others. In this work, single-phase DyCoO3 was obtained at 900 degrees C using the solution-polymerization method. The microstructure of this material corresponds to a dendritic-type shape, with grain size between 0.2 and 8m and abundant porosity. The ultraviolet (UV) sensing characterization was performed on sintered pellets made with the as-prepared DyCoO3 powder. The UV source was a light emitting diode (LED) of wavelength () of 365nm. The detection of this radiation, with constant optical irradiance (Ee), produced uniform and reproducible response patterns. When Ee was increased, the graphs revealed a quantitative detection of the light. Analogous results were obtained using light of larger wavelengths: = 400, 449, and 642nm. The graphs display a decrease on the variation of the photocurrent by increasing , corresponding to a decrease on the energy of the incoming photons. On the other hand, the photocatalytic decomposition of malachite green under UV radiation was investigated using powder of DyCoO3. The results show a decrease of the absorbance by increasing the UV exposure time, indicating the degradation of the dye. Since DyCoO3 is a p-type semiconductor material, the generation of electrical charge carriers under UV radiation explains its photocurrent and photocatalytic properties. In general, these properties can be applied in UV sensors to prevent skin cancer, photoconductive materials for solar photocells, and photocatalysis to decompose organic dyes.