Showing papers by "Akira Fujishima published in 1999"
711 citations
TL;DR: In this paper, the relationship between the photo reaction and the surface crystal structure was evaluated on the different crystal faces of rutile single crystal and also polycrystalline anatase titanium dioxide to clarify the dependence of the crystal structure on the photoinduced hydrophilic conversion.
564 citations
TL;DR: The present results indicate that diamond is a useful electrode material for the analytical detection of NADH, making it attractive for use in sensors based on enzyme-catalyzed reactions involving NADH as a cofactor.
Abstract: Conductive boron-doped chemical vapor-deposited diamond thin films, already known to have superior properties for general electroanalysis, including low background current and a wide potential window, are here shown to have additional advantages with respect to electrochemical oxidation of nicotinamide adenine dinucleotide (NADH), including high resistance to deactivation and insensitivity to dissolved oxygen. Cyclic voltammetry, amperometry, and the rotating disk electrode technique were used to study the reaction in neutral pH solution. Highly reproducible cyclic voltammograms for NADH oxidation were obtained at as-deposited diamond electrodes. The response was stable over several months of storage in ambient air, in contrast to glassy carbon electrodes, which deactivated within 1 h. The diamond electrode exhibited very high sensitivity for NADH, with an amperometric detection limit of 10 nM (S/N = 7). The response remained stable, even in the very low concentration range, for several months. In additio...
237 citations
TL;DR: Oxygen-terminated diamond electrodes were prepared by exposing as-grown diamond thin films to oxygen plasma, and the apparent surface conductivity was not significantly changed after the oxygen plasma treatment as mentioned in this paper.
229 citations
172 citations
132 citations
TL;DR: In this article, boron-doped diamond thin-film electrodes were examined for various possible applications in electroanalysis, such as dopamine and NADH oxidation using cyclic voltammetry and chronoamperometry.
129 citations
TL;DR: In this paper, photoelectrochemical characterization of semiconducting diamond was carried out in a weakly UV-absorbing aqueous electrolyte using suprabandgap illumination in order to examine the influence of electrochemical oxidative surface treatment on the energetic positions of bandedges.
Abstract: Photoelectrochemical characterization of semiconducting diamond was carried out in a weakly UV-absorbing aqueous electrolyte using suprabandgap illumination in order to examine the influence of electrochemical oxidative surface treatment on the energetic positions of bandedges. Anodic treatment of diamond photoelectrodes resulted in a positive shift in both the photocurrent onset potential and the flatband potential obtained from Mott-Schottky plots, indicating the displacement of the bandedges. A corresponding increase in the photovoltage was also observed. The pH dependence of the flatband potential of anodically treated diamond indicates an acid-base equilibrium at the interface, suggesting the formation of oxygen-containing groups. The presence of the latter was confirmed using X-ray photoelectron spectroscopy. These results suggest that the changes in the potential drop in the Helmholtz layer are due to oxygen functional groups, and the loss of surface and subsurface hydrogen are mainly responsible for the observed shifts in the flatband potentials.
82 citations
38 citations
TL;DR: In this article, a synthetic semiconductive p-type diamond electrode was photosensitized by the photoreduced Ru(bpy)31+ molecule in an electrolyte solution.
Abstract: A synthetic semiconductive p-type diamond electrode was photosensitized by the Ru(bpy)32+ molecule in an electrolyte solution. The photoexcited molecule injects a hole into the valence band. However, under a certain potential, charge recombination occurred through interband states; the hole on the top of the valence band recombined with the photoreduced Ru(bpy)31+. The mechanism of this charge recombination was studied by measuring the transient photopotential and the intrinsic sub-band gap photoresponse of the electrode.
24 citations
TL;DR: In this paper, high-level boron-doped diamond films were grown on (100) diamond substrates that were mechanically repolished at an off-axis angle of 4° with respect to the surface, tilted toward the [110] direction.
TL;DR: In this paper, the photoelectrodeposition of copper on semiconducting B-doped diamond films was investigated and it was found that changes occurring on the diamond surface during photo-electrochemical polarization in the absence of copper in solution facilitate subsequent copper electrodeposition in the dark, possibly due to the formation of subsurface hydrogen.
TL;DR: In this article, the photoelectrodeposition of copper on semiconducting B-doped diamond films was investigated and it was found that changes occurring on the diamond surface during photo-electrochemical polarization in the absence of copper in solution facilitate subsequent copper electrodeposition in the dark, possibly due to the formation of subsurface hydrogen.
Abstract: The photoelectrodeposition of copper on semiconducting B-doped diamond films was investigated. There were clear morphology differences between photoelectrodeposited and electrodeposited copper. Photoelectrodeposition proceeded by a uniform two-dimensional growth process, whereas electrodeposition involved isolated random deposition. By applying this effect we have succeeded in forming a conductive copper pattern on semiconducting B-doped diamond with the aid of a photo-mask. Interestingly, it was further found that changes occurring on the diamond surface during photoelectrochemical polarization in the absence of copper in solution facilitate subsequent copper electrodeposition in the dark, possibly due to the formation of subsurface hydrogen. We refer to this as the `photographic diamond surface phenomenon'.
TL;DR: Sensitivity to histidine of an interference-based biosensor coated with a phase transition gel is controlled by swelling and shrinking the gel, while that to imidazole is not changed significantly.
TL;DR: In this paper, a new approach for the electrochemical fingerprinting of a wide range of materials using abrasive differential pulse stripping voltammetry (AbrDPSV) at boron-doped diamond electrodes was presented.
Abstract: We present a new approach for the electrochemical fingerprinting of a wide range of materials using abrasive differential pulse stripping voltammetry (AbrDPSV) at boron-doped diamond electrodes. In this study, the abrasive stripping voltammetry of metallic Pb and Fe samples and of a brass alloy sample at diamond electrodes was carried out. The results obtained with brass indicate that the differential pulse voltammogram is an electrochemical fingerprint of the material and can be used to characterize possible interactions between the constituent metals as well as to reveal information on the chemical composition.
TL;DR: In this article, the effect of ZnO film thickness on the adhesive strength of electroless Cu deposits on glass substrates was examined and it was shown that an increase of adhesive strength was obtained with increasing film thickness, which is associated with the formation of rougher, more porous structures.
Abstract: The effect of ZnO film thickness on the adhesive strength of electroless Cu deposited on ZnO-coated glass substrates was examined. An increase of adhesive strength of the Cu deposits with increasing ZnO film thickness was observed. Excellent adhesion was obtained on ZnO films thicker than 0.6 μm, which is considered to be associated with the formation of rougher, more porous structures. XPS data combined with SEM and AFM measurements showed that in addition to the surface area effect, the mechanical anchoring effect caused by Cu depositing deeply within the ZnO film may also play an important role in obtaining the excellent adhesion of the Cu deposits on thicker ZnO films.