Effect of the particle size for photocatalytic decomposition of water on Ni-loaded K4Nb6O17

The photocatalytic activities of water splitting by small particles (0.1–2 μm) of K₄Nb₆O₁₇ were studied. The milled catalysts were prepared by two kinds of ball-milling methods from the powder whose particles were several tens of micrometers in diameter. The surface area of the milled catalyst measured by N₂ adsorption at 77 K increased by an order of magnitude. The crystal structure was almost retained as K₄Nb₆O₁₇, as evidenced by the results of X-ray diffraction and scanning electron micrography. The photocatalytic activity for an overall decomposition of water of the Ni-loaded K₄Nb₆O₁₇ was twice as high as that for the original catalyst.