Visible light induced H2 evolution on the hetero-junction Pt/CuCo2O4 prepared by hydrothermal route

The photo-electrochemistry of the hetero-junction Pt/CuCo2O4 synthesized by hydrothermal route was studied to assess its ability for the H-2 formation under visible light illumination. The X-ray diffraction is characteristic of mixed phases with narrow lines of the spinel CuCo2O4 and Pt. The sensitizer CuCo2O4 has a forbidden band (Eg) of 1.30 eV, well suited to the sun spectrum and displays p-type behavior. Its conduction band (-0.660 V-SCE), deduced from the capacitance - potential (C-2 - E) plot, is more cathodic than the H2O/H-2 level (-0.6 V-SCE), thus producing spontaneous H-2 evolution under irradiation. The photoelectrons are transferred to Pt clusters, to trigger the water reduction owing to the small H-2-over-potential. A quantum conversion yield of 0.65% is obtained under visible light (total flux: 15 mW cm(-2), 3.42 x 10(18) photons s(-1)) with H-2 evolution rate of similar to 103 mu mol g(-1) min(-1), higher than that obtained over CuCo2O4 (73 mu mol g(-1) min(-1)).