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Photoelectrochemical Manifestation of Photoelectron Transport Properties of Vertically Aligned Nanotubular TiO 2 Photoanodes
Author(s) -
Zhang Haimin,
Zhao Huijun,
Zhang Shanqing,
Quan Xie
Publication year - 2008
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.200700406
Subject(s) - photocurrent , materials science , ohmic contact , anodizing , electron transport chain , electrode , semiconductor , electron , saturation (graph theory) , photocatalysis , photoelectrochemistry , electron transfer , photoelectrochemical cell , substrate (aquarium) , optoelectronics , analytical chemistry (journal) , nanotechnology , layer (electronics) , chemistry , electrolyte , electrochemistry , photochemistry , physics , composite material , aluminium , geology , mathematics , oceanography , biochemistry , quantum mechanics , chromatography , catalysis , combinatorics
A simple photoelectrochemical method was proposed to quantitatively evaluate the electron transport process of photoelectrocatalytic oxidation of water at vertically aligned nanotubular TiO 2 photoanodes. The photoelectrocatalysis reaction resistance ( R = k / J sph + R 0 = R I + R 0 ) was measured and used to express the electron transport characteristics of a nanotubular TiO 2 electrode. The overall resistance was found to consist of a variant ( R I ) and an invariant component ( R 0 ). R I was found to be inversely proportional to the saturation photocurrent and it depends on the experimental conditions. The proportional constant, k , represents the minimum applied potential bias required to remove 100 % of the photogenerated electrons from the photocatalyst layer and was found to be independent of the anodization time. The invariant component of the resistance ( R 0 ) is an inherent property of the semiconductor photocatalyst that represents the sum of Ohmic contact impedance at the conducting substrate/TiO 2 interface and crystalline boundary impedance. The magnitude of R 0 linearly increased with anodization time. The real saturated photocurrent density ( J real‐sphd ) was found to be independent of R 0 indicating that the electron collection efficiency is independent of the nanotube length.