Hydrogen photoproduction on TiO2-CuO artificial olive leaves

[Display omitted] •Olive leaf structure successfully replicated in TiO2-CuO composites.•There is an optimum surface Cu/(Ti + Cu) mol % close to 17 for glycerol photoreforming.•H2 production of bare TiO2 was multiplied by 84 through TiO2-CuO heterojunction. Olive leaves were used as biotemplates to synthesize diverse TiO2-CuO solids. A successful replication of trichomes and internal channels was evidenced by SEM, whereas a good dispersion of Cu and Ti atoms was observed by EDX. The systems consisted in pure anatase titania, with monoclinic CuO detected by XRD and Raman for large copper contents (over 15 wt%). XPS evidenced the existence of a TiO2-CuO strong interaction. Incorporation of copper resulted in an enhancement of photocatalytic activity, hydrogen production being 84 times higher with the best TiO2-CuO system than with bare titania. It seems that there is a maximum surface copper content (close to a Cu/(Ti + Cu) mol % value of 17) above which CuO particles could promote electron-hole recombination and/or have a shielding effect thus preventing light absorption by titania. The smaller the CuO crystallite sizes the better their reducibility and the catalytic performance of the systems under solar light irradiation.