Transformation of Indium Nanoparticles to β-Indium Sulfide: Digestive Ripening and Visible Light-Induced Photocatalytic Properties

摘要

We report the transformation of polydispersedndodecanethiol stabilized indium nanoparticles, obtained fromnbulk indium shot by evaporation/condensation solvated metalnatom dispersion (SMAD) technique, into highly monodispersednpartially alkyl thiolate-capped β-indiumsulfide (In2S3)nby a postpreparative digestive ripening in high boiling point tbutyltoluenen(190 °C) solvent. Upon digestive ripening, thenas-prepared polydispersed black indium nanoparticles showedna characteristic color transition from black to cream, pale yellow, yellow, and finally to brown, indicating the transformation of thenindium metal nanoparticles into intermediates composed of indium thiolates, sulfides, and polysulfides, and finally into thenproduct In2S3 nanoparticles whose surfaces are partially capped with thiolates. The transformed product (In2S3) wasncharacterized with UV−vis, XRD, EDX, SEM, XPS, and TEM. From XRD and TEM measurements, the average size of thentransformed In2S3 nanoparticles is 5 nm. The optical absorbance of the as-prepared sample showed absorption peaks around 538nand 613 nm; upon digestive ripening these two peaks disappeared and stabilized at 375 nm, providing evidence of strongnquantum confinement of excitons. The visible light-induced photocatalytic activity test with the In2S3 nanoparticles showed thatn95% of Rhodamine B (RhB) dye degraded after 100 min of irradiation with visible light.