Photocatalytic Hydrogen Generation from Water-methanol Mixtures Using Nanocrystalline ZnFe2O4 under Visible Light Irradiation

A spinel crystal structure of ferrite containing zinc (ZnFe2O4) was synthesized by using the polymer complex method. A pure phase ZnFe2O4 was obtained at a relatively lower temperature of 900 degrees C. The as-synthesized nanoparticles are agglomerates of crystals with an average size of similar to 50 urn, as estimated from the X-ray diffraction analysis. The band gap of the n-type semiconducting metal oxide, as determined by using an ultraviolet-visible diffuse reflectance spectrometer was found to be 1.90 eV (653 nm). The photocatalytic activity of ZnFe2O4 was investigated by using the photoreduction of water under visible light (>= 420 nm), which was found to be much higher than that of the well-known TiO2-x,N-x photocatalyst. This superior performance is attributed to the larger surface area, the uniform and well-dispersed deposition of the Pt co-catalyst over the surface, and the small band gap of the chemically-prepared ferrite photocatalyst.