Photoelectrochemical properties of chemically exfoliated MoS2

Abstract

Group 6 transition metal dichalcogenides (TMD) such as MoS₂ are promising candidates for photocatalysis and photoelectrochemical applications. Despite their promise, scalable deposition of thin films remains a challenge for TMD-based photoanodes. Here we investigate the photoelectrochemical properties of ultra-thin films of chemically exfoliated MoS₂ and its composites with TiO₂ nanoparticles. We show that MoS₂ monolayer films exhibit photoelectrochemical properties similar to bulk materials, generating photocurrent at excitation wavelengths above the direct band gap edge at ∼660 nm (∼1.9 eV). We also demonstrate that MoS₂ monolayers adsorbed on TiO₂ behave as effective photosensitizers. We find that in TiO₂–MoS₂ composite photoanodes, photoexcited hot electrons in MoS₂ are able inject into TiO₂ whilst holes are removed by the electrolyte so as to generate electrical current from incident light. Our results demonstrate the potential of solution-processed MoS₂ monolayers for photoelectrochemical applications.