Search results for "Photoelectrochemistry"
showing 10 items of 49 documents
Erroneous p-type assignment by Hall effect measurements in annealed ZnO films grown on InP substrate
2013
We report on incorrect carrier type identification achieved by Hall effect measurements performed on ZnO films grown by pulsed laser deposition on InP substrates and subsequently annealed for 1 h at 600 C in air. While Hall measurements, after post-growth annealing, reveal a change in the electrical properties of the films, from n-type to p-type, both photocurrent-based and standard C V measurements performed on the same samples show no change in the native n-type doping of the ZnO films. A possible interpretation of the two results is reported. In particular, p-type conductivity observed by Hall effect may be ascribed to a highly conductive thin layer formed during the annealing process at…
Plasmonic versus catalytic effect of gold nanoparticles on mesoporous TiO2 electrodes for water splitting
2014
a b s t r a c t Solar water splitting with metal oxide semiconductors constitutes a promising approach to the conversion of solar energy into chemical energy stored in the atomic bonds of hydrogen molecules. In the present study, we evaluate the effect of the presence of Au nanoparticles on the photoelectrochemical behaviour of mesoporous TiO2 to photo-oxidize water. We observe that the presence of Au nanoparticles leads to enhanced photocurrents for water oxidation and we explore the origin of this enhancement by optical and electrochemical characterization techniques. Our results indicate that although the Au nanoparticles are responsible for a localized surface plasmonic resonance effect…
Photoelectrochemical investigation of passive layers formed on Fe in different electrolytic solutions
2004
Abstract The passive films formed on Fe in different electrolytic solutions, spanning almost the overall pH range, and with different growth procedures were investigated systematically by photocurrent spectroscopy. The potentiodynamic growth curves are compared both in aerated and de-aerated electrolytes and a potentiostatic growth procedure is also employed. For high positive formation potentials, similar anodic spectra are recorded in all solutions giving an optical gap very close to that expected for crystalline Fe2O3. The origin of photocurrent spikes is also investigated and the effect of the formation potential upon the measured absorption threshold is discussed taking into account th…
A photocurrent spectroscopic investigation of passive films on chromium
1990
Abstract Photoelectrochemical experiments have been carried out in order to identify the passive layers grown on chromium metal in different conditions. Changes in the values of the band gap of the films have been related to changes of composition, due to the different water content of the films.
Amorphous semiconductor-electrolyte junctions. Photoelectrochemical behaviour of thin Nb2O5anodic films
1987
An approach to the study of the photocharacteristics of amorphous semiconductor/electrolyte junctions is proposed which takes into account the main differences in the electronic structure and the transport properties of the amorphous semiconductors (a-SC) with respect to the crystalline counterparts. The influence of the wavelength of the incident light on the photocurrent vs electrode potential curves is explained on the basis of the geminate recombination theory in a-SC. The implications of the model are shortly discussed.
Photocurrent spectroscopy of thin passive films
2002
Publisher Summary This chapter reviews theoretical background on the photoelectrochemistry of metal and semiconductor electrodes on which photocurrent spectroscopy (PCS) relies, by focusing particularly on new features that are typical of the photoelectrochemical behavior of thin passive films and usually absent in the behavior of bulk crystalline semiconductors. The chapter also highlights the advantages of PCS in getting in situ information on the structure of the metal-passive-film-electrolyte systems and shows a more recent quantitative use of this technique in characterizing the composition of passive films. The formation of a protective film on a metallic surface is a key step in esta…
The photoelectrochemistry of thin passive layers. Investigation of anodic oxide films on titanium metal
1993
Abstract A photoelectrochemical investigation has been performed on thin TiO2 films grown anodically in 0.5 M H2SO4 solution at high growth rates. The shape of the photocurrent vs. potential curves under monochromatic irradiation (photocharacteristics) depends on the photon energy of the incident light at energies above the optical band gap of the films (3.25 ± 0.05 eV). This finding has been explained by considering the presence of geminate recombination of the photogenerated electron-hole pairs. In order to fit the experimental photocharacteristics, an expression for the photocurrent is proposed which takes into account the low drift range of photocarriers and possible recombination in th…