Publications
Sort:
Research Article Issue
Morphology-selective synthesis of active and durable gold catalysts with high catalytic performance in the reduction of 4-nitrophenol
Nano Research 2016, 9 (10): 3099-3115
Published: 25 August 2016
Downloads:20

A series of novel catalysts consisting of nanosized Au particles confined in micro-mesoporous ZSM-5/SBA-15 (ZSBA) materials with platelet (PL), rod (RD), and hexagonal-prism (HP) morphologies have been synthesized in situ. These catalysts possess both SBA-15 and ZSM-5 structures and exhibit excellent stability of their active sites by confinement of the Au nanoparticles (NPs) within ZSBA. The catalysts have been characterized in depth to understand their structure–property relationships. The gold NP dimensions and the pore structure of the catalysts, which were found to be sensitive to calcination temperature and synthetic conditions, are shown to play vital roles in the reduction of 4-nitrophenol. Au/ZSBA-PL, with short mesochannels (210 nm) and a large pore diameter (6.7 nm), exhibits high catalytic performance in the reduction of 4-nitrophenol, whereas Au/ZSBA-HP and Au/ZSBA-RD, with long mesochannels and relatively smaller pore sizes, show poor catalytic activities. In the case of catalysts with different gold NP sizes, Au/ZSBA-PL-350 with an Au NP diameter of 4.0 nm exhibits the highest reaction rate constant (0.14 min-1) and turnover frequency (0.0341 s-1). In addition, the effect of the reaction parameters on the reduction of 4-nitrophenol has been systematically investigated. A possible mechanism for 4-nitrophenol reduction over the Au/ZSBA catalysts is proposed.

Research Article Issue
Supported single Au(Ⅲ) ion catalysts for high performance in the reactions of 1, 3-dicarbonyls with alcohols
Nano Research 2016, 9 (4): 985-995
Published: 10 March 2016
Downloads:61

The high cost and poor atom utilization efficiency of noble metal catalysts have limited their industrial applications. Herein, we designed CeO2-supported single Au(Ⅲ) ion catalysts with ultra-low gold loading that can enhance the utilization efficiency of gold atoms and bridge the gap between homogeneous and heterogeneous gold catalysis. These catalysts were highly active and reusable for the reaction of 1, 3-dicarbonyls with alcohols. The catalytic turnover number of CeO2-supported single Au(Ⅲ) ion catalysts was much higher than that of the homogeneous catalyst NaAuCl4. In addition, the effects of gold loading and the drying method for the catalysts on the organic reactions were systematically explored. In-depth investigation of the structure–property relationship by highresolution transmission electron microscopy, hydrogen temperature-programmed reduction, X-ray absorption near edge structure analysis, UV–vis diffuse reflectance spectroscopy, and X-ray photoelectron spectroscopy revealed that the isolated Au(Ⅲ) ions were related to the active sites for the synthesis of β-substituted cyclohexenone and that CeO2 was responsible for yielding ketonic ester.

total 2