Rapid electroplating of photocatalytically highly active TiO2-Zn nanocomposite films on steel

Nanocomposite films consisting of TiO2 and Zn with thickness of 10-15 mum ( TiO2-Zn) have been electrodeposited on steel plates by rapid plating from a ZnSO4-based bath (I-d > 10 A dm(-2)). Upon addition of NH4NO3 to the bath (<0.3 g L-1), the uptake of TiO2 in the film significantly increased. Glow discharge optical emission spectrometry clarified that TiO2 particles were incorporated throughout the film and the loaded amount increased near the s urface. The first-order rate constant (k/h(-1)) for gas-phase CH3CHO oxidat ion was employed as an indicator of the photocatalytic activity. The k valu e for the TiO2-Zn film prepared at I-d = 12 A dm(-2) (0.20 h(-1)) was compa rable to that for the sample from a ZnCl2-based bath at I-d = 4 A dm(-2) (0 .27 h(-1)). X-ray diffraction measurements indicated that a TiO2-ZnO nanoco mposite layer was generated on the surface by the heat treatment in air at 673 K for 6 h. Consequently, the photocatalytic activity was further improv ed (k = 0.29 h(-1)); this effect was explained in terms of the synergy of T iO2 and ZnO in photocatalysis. (C) Kluwer Academic Publishers.