Probing the charge separation process on In2S3/Pt-TiO2 nanocomposites for boosted visible-light photocatalytic hydrogen production.

A simple refluxing wet-chemical approach is employed for fabricating In 2 S 3 /Pt-TiO 2 heterogeneous catalysts for hydrogen generation under visible light irradiation. When the mass ratio between Pt-TiO 2 and cubic-phased In 2 S 3 (denoted as In 2 S 3 /Pt-TiO 2 ) is two, the composite catalyst shows the highest hydrogen production, which exhibits an 82-fold enhancement over in-situ deposited Pt-In 2 S 3 . UV–vis diffuse reflectance and valence band X-ray photoelectron spectra elucidate that the conduction band of In 2 S 3 is 0.3 eV more negative compared to that of TiO 2 , favouring charge separation in the nanocomposites. Photoelectrochemical transient photo-current measurements and optical pump – terahertz probe spectroscopic studies further corroborate the charge separation in In 2 S 3 /Pt-TiO 2 . The migration of photo-induced electrons from the In 2 S 3 conduction band to the TiO 2 conduction band and subsequently into the Pt nanoparticles is found to occur within 5 ps. Based on the experimental evidence, a charge separation process is proposed which accounts for the enhanced activity exhibited by the In 2 S 3 /Pt-TiO 2 composite catalysts. [ABSTRACT FROM AUTHOR]