M/TiO2 (M = Fe, Co, Ni, Cu, Zn) catalysts for photocatalytic hydrogen production under UV and visible light irradiation

In order to improve the photocatalytic response of TiO2 to UV and visible light for hydrogen photoproduction, low cost M/TiO2 semiconductor catalysts were prepared by the impregnation method of five different first row transition metals (M = Fe, Co, Ni, Cu or Zn) on a commercial titania support. The maximum hydrogen production efficiency was achieved for the Cu/TiO2 photocatalyst, with similar to 5000 and similar to 220 mu mol h(-1) g(-1) H-2 production rates for UV and visible irradiation, respectively. Ni/TiO2 and Co/TiO2 also showed a significant photocatalytic activity when UV light was used. The best performing catalyst, Cu/TiO2, was characterized by TEM and XPS measurements. The data showed that Cu was highly dispersed over the TiO2 support and the copper species existed as both reduced Cu-0/Cu+ and oxidized Cu2+ on TiO2. Besides, during the hydrogen production reaction, the reduced Cu was partially oxidized to Cu2+ by the transfer of photogenerated holes under UV or visible light irradiation. With UV and visible lamps, the H-2 production rates were higher than those obtained with non-impregnated TiO2 by factors of 16 and 3, respectively. These results demonstrated that a Cu/TiO2 photocatalyst could be considered a promising low-cost alternative to the well-known Pt/TiO2 system for hydrogen production, making the Cu-based catalyst an ideal cost-effective candidate for this reaction.

Automated summary

Low-cost M/TiO2 semiconductor catalysts were prepared by impregnating five different first row transition metals on a commercial titania support, with Cu/TiO2 showing the best photocatalytic activity for hydrogen production under both UV and visible light. Ni/TiO2 and Co/TiO2 also exhibited significant photocatalytic activity under UV light. The Cu/TiO2 catalyst was characterized by TEM and XPS measurements, showing the dispersion of copper species on TiO2 and the oxidation-reduction process during the hydrogen production reaction. Impregnated TiO2 showed higher H-2 production rates compared to non-impregnated TiO2, making Cu/TiO2 a cost-effective alternative to Pt/TiO2 for hydrogen production.