Photochemical formation and photoelectrochemical properties of TiO2/Sb2S3 heterostructures

• Amorphous Sb2S3 nanoparticles were photocatalytically deposited on TiO2.
• Annealing of Sb2S3 gives crystalline stibnite as shown by XRD and Raman spectroscopy.
• Crystalline Sb2S3 sensitizes TiO2 to visible light in a model solar cell.

The photocatalytic deposition of antimony(III) sulfide on the surface of TiO2 films on the conductive FTO glass was investigated. The photoprocess yields particles of amorphous and almost stoichiometric Sb2S3 with a size of 150–300 nm and spherical micrometer particles enriched with Sb with a Sb:S ratio that decreases gradually from 13:1 in the particle center to 5:1 at the surface. Thermal treatment of the FTO/TiO2/Sb2S3 films at 350 °C results in the transformation of amorphous antimony(III) sulfide into crystalline stibnite without extensive changes in the film morphology.The crystalline FTO/TiO2/Sb2S3 films exhibit photoelectrochemical activity when illuminated in the spectral range of λ > 350 nm in aqueous solutions of ascorbic acid as a sacrificial electron donor. The maximal photocurrent density generated by the TiO2/Sb2S3 heterostructure is higher than the photoresponse of the starting FTO/TiO2 film by a factor of 3.6. Deposition of an intermediary layer of Inx(OH)ySz on the interface between TiO2 and Sb2S3 results in a further 3-fold increase in the photoelectrochemical activity of the FTO/TiO2/Sb2S3 heterostructure.

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