Well-defined gold nanoclusters with average size less than 2 nm have emerged as a new and novel catalyst. The gold nanocluster loaded on the oxide surface usually aggregates to larger particles at high temperature （〉 300℃）, which is caused by the removal of the surface ligands. We herein pre-sent a novel method to prepare Au25cluster catalyst （-1.3 nm） with high thermal stability （up to 400℃）. Au25@Si02 is synthesized via a co-hydrolyzing reaction of Au2s[SC3H6Si（OCH3）3118 and tet-raethyl orthosilicate, and then it is treated at different temperature （e.g., 200, 300, 400℃） in air to remove the organic ligands. Au25@SiO2 is well characterized by transmission electron microscopy, ultraviolet-visible spectroscopy and diffuse reflectance UV-vis spectroscopy. Further, the Au2s@SiO2 catalysts are investigated in the hydrogenation ofp-nitrophenol into p-aminophenol.
We present an efficient approach for the chemoselective synthesis of arylamines from nitroarenes and formate over an oxygen-implanted MoS2 catalyst（O-MoS2）.O-MoS2 was prepared by incomplete sul idation and reduction of an ammonium molybdate precursor.A number of Mo-O bonds were implanted in the as-synthesized ultrathin O-MoS2 nanosheets.As a consequence of the different coordination geometries of O（Mo O2） and S（MoS2）,and lengths of the Mo-O and Mo-S bonds,the implanted Mo-O bonds induced obvious defects and more coordinatively unsaturated（CUS） Mo sites in O-MoS2,as confirmed by X-ray diffraction,Raman spectroscopy,X-ray photoelectron spectroscopy,high resolution transmission electron microscopy,and extended X-ray absorption fine structure characterization of various MoS2-based materials.O-MoS2 with abundant CUS Mo sites was found to efficiently catalyze the chemoselective reduction of nitroarenes to arylamines.
Chaofeng ZhangXu WangMingrun LiZhixin ZhangYehong WangRui SiFeng Wang
