Visible light induced hydrogen on the novel hetero-system CuFe2O4/TiO2

The hydrogen photo evolution has been successfully achieved over the new hetero-system CuFe2O4/TiO2 and the activity is dependent on the synthesis method. The spinel CuFe2O4 is p-type semi conductor with activation energy of 0.21 eV. It has been prepared via a variety of techniques and the best performance is achieved on the catalyst elaborated by sol gel. The onset potential of the photocurrent (−0.17 VSCE) is slightly cathodic with respect to the flat band potential (0 VSCE) implying a small existence of surface states within the gap region. The photo induced minority carriers (electrons) react with H2O molecules via TiO2 interfacial mechanism. The intimate contact between CuFe2O4 and TiO2 particles is necessary for H2 liberation. The generated photovoltage is used to catalyze the reaction (H2O+S2O32-+2OH-→2H2+2SO32-,ΔGR∘=-39.31kJmol-1) and the oxide approaches 100% stability to photo driven corrosion. The rate of H2 evolution is found to be 15 μmol g−1 min−1 with a polychromatic power efficiency of 1.3%. Over time, a pronounced deceleration occurred. The competitive reduction of sulfite is therefore though to be the reason of the regression of the photoactivity.

► CuFe2O4 has proved an efficient photocatalyst for the hydrogen evolution.
► The photoactivity of the hetero-system CuFe2O4/TiO2 is strongly affected by the pH.
► The cationic conduction band of CuFe2O4 (−1.21 VSCE), provides high reducing power.
► Parameters selection (pH and mass concentration) crucial in the photoactivity.