Photoelectrochemical properties of chemically exfoliated MoS2

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 ultrathin 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 similar to 660 nm (similar to 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.