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Photoelectrochemical Water Splitting Using Dense and Aligned TiO 2 Nanorod Arrays
Author(s) -
Wolcott Abraham,
Smith Wilson A.,
Kuykendall Tevye R.,
Zhao Yiping,
Zhang Jin Z.
Publication year - 2009
Publication title -
small
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.785
H-Index - 236
eISSN - 1613-6829
pISSN - 1613-6810
DOI - 10.1002/smll.200800902
Subject(s) - nanorod , water splitting , materials science , anatase , photoelectrochemical cell , indium tin oxide , optoelectronics , scanning electron microscope , photoelectrochemistry , analytical chemistry (journal) , nanotechnology , photocatalysis , thin film , electrode , electrochemistry , electrolyte , chemistry , biochemistry , chromatography , catalysis , composite material
Dense and aligned TiO 2 nanorod arrays are fabricated using oblique‐angle deposition on indium tin oxide (ITO) conducting substrates. The TiO 2 nanorods are measured to be 800–1100 nm in length and 45–400 nm in width with an anatase crystal phase. Coverage of the ITO is extremely high with 25 × 10 6 mm −2 of the TiO 2 nanorods. The first use of these dense TiO 2 nanorod arrays as working electrodes in photoelectrochemical (PEC) cells used for the generation of hydrogen by water splitting is demonstrated. A number of experimental techniques including UV/Vis absorption spectroscopy, X‐ray diffraction, high‐resolution scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, and photoelectrochemistry are used to characterize their structural, optical, and electronic properties. Both UV/Vis and incident‐photon‐to‐current‐efficiency measurements show their photoresponse in the visible is limited but with a marked increase around ≈400 nm. Mott–Schottky measurements give a flat‐band potential ( V FB ) of +0.20 V, a carrier density of 4.5 × 10 17 cm −3 , and a space‐charge layer of 99 nm. Overall water splitting is observed with an applied overpotential at 1.0 V (versus Ag/AgCl) with a photo‐to‐hydrogen efficiency of 0.1%. The results suggest that these dense and aligned one‐dimensional TiO 2 nanostructures are promising for hydrogen generation from water splitting based on PEC cells.