Water-Soluble MoS₃ Nanoparticles for Photocatalytic H₂ Evolution

Polyvinylpyrrolidone (PVP)-modified MoS₃ nanoparticles with unusual water solubility up to 1.0 mgmL^-1 were synthesized through a facile hydrothermal method in the presence of thioacetic acid. The amorphous nanoparticles wrapped by PVP have sizes of around 2.5 nm, which represent the smallest MoS₃ clusters reported. The photocatalytic performance of the MoS₃ nanoparticles was evaluated under visible light for H₂ evolution using xanthene dyes as photosensitizers. The quantum efficiency of the optimized system for H₂ evolution under green light irradiation (520 nm) is up to 36.2 %, which is comparable with those of other excellent photocatalytic systems involving earth-abundant catalysts. The excellent photocatalytic activity can be attributed to its good dispersion in water, amorphous nature and limited layers with abundant surface active sites, and possibly higher conduction band potential for proton reduction and larger indirect band gap for a longer lifetime of the excited electrons.