The Applicability of Semiconducting Layered Materials for Electrochemical Solar Energy Conversion

Abstract

Abstract Semiconducting transition metal dichalcogenides with layer structure belong to the most stable electrode materials in electrochemical solar cells. The photoelectrochemical reactions however, are complicated by the surface anisotropy. Results of photoelectrochemical cells with n‐type MoSe 2 and WSe 2 demonstrate the importance of surface morphology for the energy conversion efficiency. — The optimal energy conversion yield of these layered semiconductors has turned out being lower than theoretically expected from their band gaps. It is shown that this is connected with the existence of an indirect band gap which restricts light absorption in a considerable energy quantum range above the band gap. Besides this, surface defects and inhomogeneities reduce the quantum yield by increased surface recombination. — Photoelectrochemical hydrogen evolution has been investigated with p‐type WSe 2 . It is shown that a considerable energy gain can be reached by the catalytic action of platinum deposits on the surface of the electrode. This is explained in terms of surface state catalysis.