Formation of CuO on TiO2 Surface Using its Photocatalytic Activity

Abstract

Some co-catalyst nanoparticles can enhance the activity of photocatalysts due to prolonging the charge separation lifetime by promoting the electron or hole transfer. CuO particles were prepared from an aqueous solution of copper (II) nitrate at 351 K on a TiO2 surface by a photocatalytic reaction and heating at 573 or 673 K. The amount and size of the particles deposited during the photocatalytic reaction can be controlled by changing the amount of the irradiated photons. The CuO crystals with about 50−250 nm-sized particles were formed. Nitrate ions were reduced to nitrite ions in the solution by the photocatalytic activity of the TiO2, and water was simultaneously transformed into hydroxide ions. An increase in the basicity on the TiO2 surface induced formation of a copper hydroxide. The copper hydroxide was subsequently dehydrated and transformed into CuO by heating. The TiO2 loading of a small amount of CuO demonstrated a higher photocatalytic activity for methylene blue degradation compared to the original TiO2 due to the electron transfer from the TiO2 conduction bands to the CuO conduction band.