Photoluminescence Mapping of Atomically Layered Photocatalysts

Abstract

Light–driven chemical transformation via interfacial photocatalytic reactions has the potential to revolutionize energy production and sustainable chemical industry. Atomically thin materials offer a promising solution to construct efficient photocatalysts owing to their exceptional tunability of optical and electronic characteristics. In the atomic scale, the photogenerated electrons and holes are bounded as neutral quasiparticles, known as excitons. This excitonic effect limits the utilization of free carriers and results in diminished quantum efficiency in the light–driven redox processes. In this work, van der Waals heterojunctions composed of tungsten disulfide (WS2) and molybdenum disulfide (MoS2) were created to facilitate the transition of excitons into free carriers. Spatially resolved photoluminescence (PL) spectra were obtained to quantify the photoemission from the radiative decay of excitons. At the heterojunction formed by WS2 and MoS2, the strong quenching of PL was attributed to rapid charge separation and exciton dissociation. The results highlight the opportunities to leverage van der Waals heterojunctions to manipulate the excitonic effects for efficient photocatalysis.