Preparation, characterization and photocatalytic activity of size selected platinum nanoclusters

• Preparation of size selected platinum clusters protected by l-GSH, NALC and l-Pen.
• Characterization of synthesized clusters by TGA, TEM, UV–vis, FTIR and N2 sorption.
• The synthesized clusters were supported over Degussa TiO2 by impregnation method.
• 1% Pt clusters/TiO2 used as a catalyst in solar degradation of methylene blue dye.

Herein, we report the synthesis and characterization of some water-soluble thiol monolayer protected platinum nanoclusters (PtNCs).The cluster material obtained by the reduction of the corresponding metal salt with NaBH4 in presence of water-soluble ligands, L-glutathione (L-GSH) reduced, N-acetyl-L-cysteine (NALC) and L-penicillamine (L-Pen), acting as capping ligands. Platinum nanoclusters with around 1 nm sizes were isolated and characterized by transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). The optical properties of the samples were studied by UV–vis spectroscopy. Fourier transform infrared spectroscopy (FTIR) was measured for the free ligands and protected PtNCs where the disappearance of the SH vibrational band (2535–2570 cm−1) in the platinum nanoclusters confirmed anchoring of ligand to the cluster surface through the sulfur atom. Textural features of the obtained cluster catalysts were investigated using nitrogen adsorption-desorption at −196 °C. Specific surface area SBET, pore volume and average pore diameter were calculated. The prepared clusters were used to load size selected platinum clusters onto Degussa TiO2 P25 to create photocatalysts absorb the visible light. The resulting materials showed high photocatalytic activity in decomposition of methylene blue dye (MB) after irradiation by solar light.

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