Hole Reactions from d‐Energy Bands of Layer Type Group VI Transition Metal Dichalcogenides: New Perspectives for Electrochemical Solar Energy Conversion

Abstract

Holes, photogenerated in d‐energy bands of covalent semiconducting layer‐type group VI ‐transition metal dichalcogenides react electrochemically differently from holes generated in semiconductors with valence bands based on p‐orbitals (e.g., normalCdS , normalZnO , normalCdSe , normalGaAs ). They do not constitute broken crystal bonds and do therefore not lead directly to an anodic photodecomposition of the electrode. The chemical character of these holes as missing d‐electrons, on the other hand, gives rise to very specific electrochemical surface reactions with electron donors such as I−, Br−, and even OH−, for example. The specific nature of the interfacial charge transfer complexes formed, their advantageous effect on the potential distribution in the electrode surface, and their favorable oxidation potential (in the case of the photoreaction with OH− ions), respectively, may be the clue to a promising new approach to several unaccomplished goals of photoelectrochemical research, among them the construction of stable regenerative electrochemical solar cells and the oxidation of water with visible light. Photoelectrochemical measurements performed with MoSe2 single crystals as well as experiments on solar energy conversion and photoelectrochemical reactions with water induced by visible and near infrared light are described as experimental evidence in support of this finding.

PLD Grown Polycrystalline Tungsten Disulphide (WS2) Films

“…The rising interest and research on alternative, abundant, and nontoxic absorber materials like tungsten disulfide (WS 2 ) could play a major role to advance the photovoltaics field and renewable energy market [1][2][3][4][5][6][7]. WS 2 is layered transition metal dichalcogenide (TMDC) material.…”

Transport property measurements in tungsten sulphoselenide single crystals grown by a CVT technique

“…These LTMDCs have been used for many years as solid state lubricants [2], photovoltaic/photocatalytic solar energy converters [3], Schottky [4] and liquid junction solar cells [5,6], as catalysts in many industrial applications [7] and in secondary batteries [8] etc.…”

Erratum: “The Effect of SO 3 Gas on the Surface Tension of Molten Na2 SO 4” [J. Electrochem. Soc., 129, 2232 (1981)]

“…The latter equation, which is based on Jaeger's data (1), may be found in the recent compilation of surface tension data by Janz et at. (2). Although Eq.…”