Mesoporous TiO2 Photoelectrodes for Solar Hydrogen Generation

Title
Mesoporous TiO2 Photoelectrodes for Solar Hydrogen Generation
Authors
Pascal Hartmann이도권Bernd SmarslyJurgen Janek
Keywords
mesoporous TiO2; solar hydrogen; solar water splitting; photoelectrochemical
Issue Date
2010-09
Publisher
ZEITSCHRIFT FUR ANORGANISCHE UND ALLGEMEINE CHEMIE
Citation
VOL 636, NO 11, 2048-2048
Abstract
In the present work we prepared nanocrystalline mesoporous thin film (mp-TiO2) either using TiCl4 as classical precursor for a sol-gel procedure or using crystalline TiO2 nanoparticles as precursor. Well defined porosity was introduced via an evaporation-induced self assembly (EISA) process of blockcopolymers [1]. Both types of mp-TiO2 thin films were characterized with respect to their efficiency in photoelectrochemical hydrogen generation. Besides photoelectrochemistry, wide and small angle scattering, scanning electron microscopy, optical absorption and secondary ion mass spectrometry experiments were carried out to characterize the films. As a major result we show that only small differences in the micro- and mesostructure lead to tremendous differences in PEC water splitting efficiencies: SEM investigations have shown that both films feature the same type of mesoporosity with a pore diameter of about 15 nm and large crack free areas. The nanoparticle films show a higher density of accessible pores at the surface than the sol-gel samples. Films prepared by the sol-gel process have a significantly thicker TiO2 framework with about 15 nm thick pore walls compared to 7 nm - 8 nm of the nanoparticles. The external quantum efficiency ηQE or photon-to-current efficiency (IPCE) gives the ratio between the number of incident photons and generated electronic charge carriers, and therefore, the amount of produced H2 and O2. In our experiments the solgel samples have shown a maximum IPCE of about 40 % which is about 10 times higher than for the nanoparticle based films. The minor efficiency can be related with the low interconnectivity of the sphere-shaped nanoparticles.
URI
http://pubs.kist.re.kr/handle/201004/44582
ISSN
00442313
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