We present the photoelectrochemical characteristics of TiO 2 nanoparticle-based photoanodes. TiO 2 nanoparticles (P25) were deposited on fluorine-doped tin oxide (FTO) substrate by spin-coating and thermally annealed in a vacuum for enhancing the active photocatalyst. At a potential of 0.4 V (versus a reversible hydrogen electrode), the annealed TiO 2 nanoparticle-based photoanode in vacuum shows a photocurrent density of 0.27 mA/cm 2 and photoconversion efficiency of (η = 0.22%), which are higher than those an of annealed TiO 2 nanoparticle-based electrode in air. The improved photoelectrochemical properties are attributed to high oxygen vacancy (OV) density with more active sides while TiO 2 nanoparticles are annealed in a vacuum (~1.33 × 10 −2 kPa) with low oxide concentration conditions. From this finding, we propose that thermal annealing can serve as an approach for fabricating the photoanodes of TiO 2 -based material consisting of a more active photocatalyst.

The N,O-bidentate ligand 2-((methylimino)methyl)pyren-1-ol (1) gives with nickel acetate in a mixed solvent of toluene and ethanol in the presence of NaOAc the nickel(II) complex 1(Ni). It was characterized by elemental analysis, IR, NMR, MS spectroscopy and single crystal X-ray diffraction. With respect to the nickel atom the complex 1(Ni) adopts a distorted square planar trans-coordination geometry. Concerning the ligand arrangement, complex 1(Ni) has a step configuration with the angle of 35.5o between the mean planes of the pyrene rings in the two independent molecules and step distance S = 1.93 Å, whereas the referent nickel(II) bis(salicylaldiminato) takes a much smaller step configuration with an angle of 17.6o and the step distance S = 0.845 Å (chart 1).

In this paper, we present the electrochemical water splitting characteristics of TiO2/FTO electrodes via spin-coating method. By using thermal annealing approach, the TiO2 nanoparticle (P25) was modified with a more active photocatalyst. The annealed TiO2 nanoparticle-based photoanode in vacuum shows photocurrent density of 0.27 mA/cm2 and photoconversion efficiency of (η = 0.22%) at potential of 0.4 V (vs. RHE), which are higher than those of annealed TiO2 nanoparticle-based electrode in air. The improved photoelectrochemical property is attributed to high oxygen vacancy density with more active sides, while TiO2 nanoparticle was annealed in vacuum (∼10−1 torr) with oxide concentration conditions. From this finding, we propose that a thermal annealing process might serve as an approach for fabricating the photoanodes of TiO2-based materials consisting of much active photocatalyst