Abstract
Hierarchical TiO2 / RuO2 nanorod heterostructure was synthesized. Amorphous TiO2 layer was firstly spin-coated onto RuO2 nanorods on Si wafer prepared by RF sputtering. The amorphous layer was transformed to titanate with special morphology under acetic acid solvothermal reaction. After heating at 700 oC for 1 h, the titanate further transfer to anatase without morphology change. Three kinds of morphology of TiO2 were synthesized, including submicron-particle, flower-like, and nanoparticles. Furthermore, the varied-morphologied TiO2 / RuO2 nanorods heterostructure was used as working electrode for photoelectrochemical water splitting in 1 M KOH aqueous solution. It showed larger photocurrent enhancement (2.20 mA/cm2 at 0.2 V vs Ag/AgCl) compared with that of TiO2 nanoparticles / RuO2 nanorods (1.16 mA/cm2 at 0.2 V vs Ag/AgCl) and that of TiO2 submicron-particles (1.48 mA/cm2 at 0.2 V vs Ag/AgCl) under the irradiation of a Xe lamp. However, the photocurrent enhancement and photostability of TiO2 / RuO2 nanorod heterostructure with varied thickness drop largely when the thickness of the sample exceeds 6 μm. From the outcome above, the optimum thickness is around 2 μm, and the performance of flower-like TiO2 is the best among the three morphologies. These suggest the hierarchical heterostructure that TiO2 flower / RuO2 nanorods can be employed as a potential photoanode for photoelectrochemical water splitting.