A comparative study of the deposition of nanoscale Au–S intermediates from aqueous solutions on CuO, TiO₂, AND α-Fe₂O₃ surfaces

Products of the interaction between dispersed copper(II), iron(III) (hematite), and titanium(IV) (rutile) oxides and aqueous solutions containing liquid prenucleation intermediates formed in the reaction of HAuCl₄ and sodium sulfide with the initial 1:3 molar ratio of the reagents are studied by X-ray photoelectron spectroscopy, Cu L-, Fe L-, Ti L-, O K X-ray absorption near edge structure spectroscopy in combination with transmission electron microscopy. It is found that in comparison with treatment of supports with a HAuCl₄ solution, the amount of deposited gold significantly increases in the presence of sulfide ions. Gold nanoparticles covered with adsorbed sulfur form on three studied oxides as a decomposition product of strongly disordered gold(I) sulfide. On copper oxide, discernibly larger gold nanoparticles (with a diameter of about 10 nm against 3-5 nm on hematite and rutile) are observed. The surface of the support is sulfidized.