Photocatalytic Water Splitting on Rh/K₄Nb₆O₁₇ Nanosheets

The layered potassium niobate, K₄Nb₆O₁₇, is known as a photocatalyst for hydrogen production from water splitting under UV light. Here we show that potassium niobate nanosheets can be obtained by exfoliation of K₄Nb₆O₁₇ followed by proton exchange. Photocatalytic water splitting has been improved in this work by loading Rh nanoparticles as cocatalyst. The catalysts were characterized by powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy analysis (XPS), and ultraviolet-visible spectroscopy (UV-vis), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Their photocatalytic activities were in (i) an aqueous MeOH, used as sacrificial hole scavengers for hydrogen production and (ii) pure water for hydrogen and oxygen production under UV light irradiation. The potassium niobate nanosheets with uniform dispersion of Rh nanoparticles exhibited a very high photocatalytic overall water splitting activity, where the H₂ production and O₂ production rate were 142 μmol h^-1 g^-1 and 68 μmol h^-1 g^-1, which was about 10 times higher than that exhibited by the origin K₄Nb₆O₁₇ photocatalyst.