Revealing the Role of Chain Length of Ligands on Gold Nanoparticles Surface in the Process for Catalysis Reduction of 4-Nitrophenol

The hindrance of ligands chain arising from colloidal nanoparticle (NPs) surface in the process for different kinds of colloidal Au NPs catalyzed reduction of 4-nitrophenol (4-NP) is presented. The hindrance around Au NPs is controlled by varying the length of chain ligands coated on Au NPs. As the length of the ligand chain shortens, the catalytic activity of colloidal Au NPs got significant promotion for the 4-NP reduction reaction. Till inorganic sulfide ion as surface ligand, the catalytic activity of Au@S2− NPs reached the top. Moreover, by grafting different organic chain ligands of quaternary ammonium salts into Au@S2− NPs to vary the length of ligands, we can realize the regulation of catalytic reaction rate during the procedure of the reduction of 4-NP. In particular, Au@S2− NPs also exhibited excellent catalytic cycle stability.