Monoclinic BiVO(4) crystals with preferentially exposed (040) facets were hydrothermally synthesized by using a trace amount of TiCl(3) as the directing agent; this function was confirmed by X-ray diffraction patterns (XRD) and high-resolution transmission electron microscopy (HRTEM). The effects of the directing agent TiCl(3) and the pH values applied during synthesis have been studied, and the optimized BiVO(4) sample with highly exposed (040) facet could be obtained by using 1.2 at.% of TiCl(3) as the directing agent at a pH value of 2. Some complementary techniques were also applied to exclude the effects of the structural and physical property changes, such as surface area and hydrophilicity. The photocatalytic activity of oxygen evolution on BiVO(4) is found to be proportionally correlated with the exposed surfaces of the (040) facet. It is assumed that the active sites with a BiV(4) structure on the exposed (040) facet is assigned to be responsible for the high activity of O(2) evolution.

Zinc orthogermanate was prepared via a hydrothermal method and a remarkable synergistic effect on the photocatalytic activity for overall water splitting was found for Zn 2 GeO 4 co-loaded with noble metals (Pt, Rh, Pd, Au) and metal oxides (RuO 2 , IrO 2 ). The photocatalytic activity of Pt-RuO 2 /Zn 2 GeO 4 for overall water splitting is 2.2 times of Pt/Zn 2 GeO 4 and 3.3 times of RuO 2 /Zn 2 GeO 4 . Photocatalytic half reactions evaluation of water splitting for H 2 and O 2 productions shows that Pt plays the major roles in H 2 production and RuO 2 promotes the O 2 production. The roles and valence states of co-catalysts and the mechanism of photocatalytic reaction are discussed.

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