Eine Halbleiterhybrid-Elektrode zum wellenlängengesteuerten Schalten der Photostromrichtung

Switched Photocurrent on Tin Sulfide-Based Nanoplate Photoelectrodes

A new type of SnS₂ nanoplate photoelectrode is prepared by using a mild wet-chemical method. Depending on the calcination temperatures, SnS₂ -based photoelectrodes can either retain their n-type nature with greatly enhanced anodic photocurrent density (ca. 1.2 mA cm^-2 at 0.8 V vs. Ag/AgCl) or be completely converted into p-type SnS to generate approximately 0.26 mA cm^-2 cathodic photocurrent density at -0.8 V vs. Ag/AgCl. The dominance of sulfur and tin vacancies are found to account for the dramatically different photoelectrochemical behaviors of n-type SnS₂ and p-type SnS photoelectrodes. In addition, the band structures of n-type SnS₂ and p-type SnS photoelectrodes are also deduced, which may provide an effective strategy for developing SnS₂ /SnS films with controllable energy-band levels through a simple calcination treatment.

The electrochemistry of nanostructured titanium dioxide electrodes

Several of the multiple applications of titanium dioxide nanomaterials are directly related to the introduction or generation of charge carriers in the oxide. Thus, electrochemistry plays a central role in the understanding of the factors that must be controlled for the optimization of the material for each application. Herein, the main conceptual tools needed to address the study of the electrochemical properties of TiO(2) nanostructured electrodes are reviewed, as well as the electrochemical methods to prepare and modify them. Particular attention is paid to the dark electrochemical response of these nanomaterials and its direct connection with the TiO(2) electronic structure, interfacial area and grain boundary density. The physical bases for the generation of currents under illumination are also presented. Emphasis is placed on the fact that the kinetics of charge-carrier transfer to solution determines the sign and value of the photocurrent. Furthermore, methods for extracting kinetic information from open-circuit potential and photocurrent measurements are briefly presented. Some aspects of the combination of electrochemical and spectroscopic measurements are also dealt with. Finally, some of the applications of TiO(2) nanostructured samples derived from their electrochemical properties are concisely reviewed. Particular attention is paid to photocatalytic processes and, to a lesser extent, to photosynthetic reactions as well as to applications related to energy from the aspects of both saving (electrochromic layers) and accumulation (batteries). The use of TiO(2) nanomaterials in solar cells is not covered, as a number of reviews have been published addressing this issue.