This paper reports the investigations on the preparation and hydrogen-evolving performance of CoO modified-TiO₂ photocatalysts, and the photoelectrochemical performance with the methods of successive sudden photocurrent-time and cyclic voltammetry. The differences between CoO modified and pure TiO₂ photocatalysts on intensity of photocurrent response, starting-response speed and hydrogen-evolving photopotential were discussed in detail. The results showed that an appropriate amount of CoO loading could obviously enhance the hydrogen generation rate from water with a satisfied stability during experimental period. And the optimum loading content of Co was 0.4%. The hydrogen-evolving rate increased from 2.9×10^－3 mL•h^－1 of pure TiO₂ to 2.85×10^－1 mL•h^－1 of CoO-TiO₂ photocatalyst with 0.4% Co content (ca. two order of magnitude). The results of the photoelectrochemical performance under a UV light illuminating condition showed that the CoO modification on the TiO₂ photocatalyst enhanced the photocurrent response intensity in an order of 3.0% Co＞0.4% Co＞0.0% Co. The photocurrent starting-response speed of the higher CoO modified-TiO₂ photocatalyst decreased with an order of 3.0% Co＜0.4% Co≈0.0% Co. But on the other hand, under a visible light illuminating condition, the value order of intensity of photocurrent response was changed to be 0.4% Co＞0.0% Co＞3.0% Co, and the photocurrent starting-response speed was almost the same for studied samples.

Key words: photocatalysis, photoelectrochemistry, CoO modified TiO₂, hydrogen production