Probing the Charge Separation Process on In2S3/Pt-TiO2 Nanocomposites for Boosted Visible-light Photocatalytic Hydrogen Production

TL;DR

This study develops In2S3/Pt-TiO2 nanocomposites via a simple method, demonstrating significantly enhanced visible-light photocatalytic hydrogen production due to efficient charge separation and rapid electron migration within the composite.

Contribution

It introduces a novel In2S3/Pt-TiO2 nanocomposite catalyst with optimized charge separation for improved hydrogen generation under visible light.

Findings

82-fold increase in hydrogen production over previous catalysts

Charge separation occurs within 5 picoseconds in the nanocomposite

Conduction band alignment facilitates electron transfer for enhanced photocatalysis

Abstract

A simple refluxing wet-chemical approach is employed for fabricating In2S3/Pt-TiO2 heterogeneous catalysts for hydrogen generation under visible light irradiation. When the mass ratio between Pt-TiO2 and cubic-phased In2S3 (denoted as In2S3/Pt-TiO2) is two, the composite catalyst shows the highest hydrogen production, which exhibits an 82-fold enhancement over in-situ deposited Pt-In2S3. UV-vis diffuse reflectance and valence band X-ray photoelectron spectra elucidate that the conduction band of In2S3 is 0.3 eV more negative compared to that of TiO2, favoring charge separation in the nanocomposites. Photoelectrochemical transient photo-current measurements and optical pump - terahertz probe spectroscopic studies further corroborate the charge separation in In2S3/Pt-TiO2. The migration of photo-induced electrons from the In2S3 conduction band to the TiO2 conduction band and subsequently into the Pt nanoparticles is found to occur within 5 picoseconds. Based on the experimental evidence, a charge separation process is proposed which accounts for the enhanced activity exhibited by the In2S3/Pt-TiO2 composite catalysts.