The principle of p-n type semiconductor composite photocatalysts is discussed as a strategy to develop efficient photocatalysts for water splitting. Composite of p-type and n-type semiconductor has an advantage in taking full use of each semiconductor's function of oxidation and reduction

which could facilitate the photo-induced electron/hole pairs' separation by the inner electric field

enhancing the photocatalytic efficiency of the system. CuCrO2 was synthesized by a novel combustion reaction method with glycerin as fuel

and WO3 was prepared by the tungsten acid decomposition method. The configurations CuCrO2-WO3 and Ru/(CuCrO2-WO3) were successfully prepared by mechanical grinding and heat-treatment. The prepared samples were characterized by using X-ray diffraction (XRD)

ultraviolet-visible diffuse reflectance (UV-vis DR)

scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). The photocatalytic activities of CuCrO2

WO3

CuCrO2-WO3 and Ru/(CuCrO2-WO3) were evaluated under xenon lamp irradiation. The factors including pH of grinding media and Ru loading were also investigated. When glycerin was used as the sacrificial reagent under xenon lamp irradiation

CuCrO2 or WO3 powders alone was not able to catalyze H2 generation from water splitting

while coupled photocatalysts of CuCrO2-WO3 displayed remarkable photocatalytic activity. The improvement of photocatalytic activity was attributed to the formation of p-n junctures at the interface of CuCrO2-WO3. When grinding media was at pH 8

dispersion of WO3 was particularly better

which contributed to more efficient compounding of the two powders and better activity of the composite as a consequence. Ru loading as cocatalyst also remarkably enhanced photocatalytic hydrogen production. The 0.5% (mass) Ru/(CuCrO2-WO3) exhibited better photocatalytic activity for splitting pure water into hydrogen under 300W xenon lamp irradiation

on which H2 production was about 10 μmol for 3 h.