A series of Mn-doped K-Co-Mo catalysts were prepared by a sol-gel method. The catalyst structure was well characterized by X-ray diffraction, N2 physisorption, NH3 temperature- programmed adsorption, in situ diffuse r...A series of Mn-doped K-Co-Mo catalysts were prepared by a sol-gel method. The catalyst structure was well characterized by X-ray diffraction, N2 physisorption, NH3 temperature- programmed adsorption, in situ diffuse reflectance infrared Fourier transform spectroscopy, and X-ray absorption fine structure spectroscopy. The catalytic performance for higher alcohol synthesis from syngas was measured. It was found that the Mn-doped catalysts ex- hibited a much higher activity as compared to the unpromoted catalyst, and in particular the C2＋ alcohol selectivity increased significantly. The distribution of alcohol products de- viated from the Anderson-Schulz-Flory law. The portion of methanol in total alcohol was suppressed remarkably and the ethanol became the predominant product. Characterization results indicated that the incorporation of Mn enhanced the interaction of Co and Mo and thus led to the formation of Co-Mo-O species, which was regarded as the active site for the alcohol synthesis. Secondly, the presence of Mn reduced the amount of strong acid sites significantly and meanwhile promoted the formation of weak acid sites, which had a positive effect on the synthesis of alcohol. Furthermore, it was found that the incorporation of Mn can enhance the adsorption of linear- and bridge-type CO significantly, which contributed to the formation of alcohol and growth of carbon chain and thus increased the selectivity to C2＋OH.展开更多
Fe3C-functionalized three-dimensional （3D） porous nitrogen-doped graphite carbon composites （Fe3C/ NG） were synthesized via a facile solution-based impreg- nation and pyrolysis strategy using the commercially avai...Fe3C-functionalized three-dimensional （3D） porous nitrogen-doped graphite carbon composites （Fe3C/ NG） were synthesized via a facile solution-based impreg- nation and pyrolysis strategy using the commercially available melamine foam and FeC13 as precursors. The structural characterizations confirmed that Fe3C nanoparticles with an average core size about 122 nm were assembled on the surface of the carbonized melamine foam （CMF） skeletons. The electrochemical measurements demonstrated the superior electrocatalytic activity of the advanced Fe3C/NG composite for hydrogen peroxide reduction reaction in 0.1 mol/L PBS electrolyte and the limit of detection of H2O2 is estimated to be 0.035 mmol/L at a signal-to-noise ratio of 3 with a wide linear detection range from 50 μmol/L to 15 mmol/L （R^2 = 0.999）. Compared with the pure CMF, the Fe3C/NG exhibited higher catalytic activity, more stable response, lower detection limit, higher selectivity and a wider detection range, which could be attributed to the synergic effect between the two types of active sites from the iron carbide species and the nitrogen-doped graphite carbon. Meanwhile, the large surface area, high conductivity and the improved mass transport from the 3D porous material can also promote the electrochemical sensing performance. Moreover, the Fe3C/ NG-based electrochemical sensor showed high anti-interference ability and stability for H2O2 detection. Thus, the novel and low-cost Fe3C/NG composite may be a prom- ising alternative to noble metals and offer potential appli- cations in various types of electrochemical sensors, bioelectronic devices and catalysts.展开更多
文摘A series of Mn-doped K-Co-Mo catalysts were prepared by a sol-gel method. The catalyst structure was well characterized by X-ray diffraction, N2 physisorption, NH3 temperature- programmed adsorption, in situ diffuse reflectance infrared Fourier transform spectroscopy, and X-ray absorption fine structure spectroscopy. The catalytic performance for higher alcohol synthesis from syngas was measured. It was found that the Mn-doped catalysts ex- hibited a much higher activity as compared to the unpromoted catalyst, and in particular the C2＋ alcohol selectivity increased significantly. The distribution of alcohol products de- viated from the Anderson-Schulz-Flory law. The portion of methanol in total alcohol was suppressed remarkably and the ethanol became the predominant product. Characterization results indicated that the incorporation of Mn enhanced the interaction of Co and Mo and thus led to the formation of Co-Mo-O species, which was regarded as the active site for the alcohol synthesis. Secondly, the presence of Mn reduced the amount of strong acid sites significantly and meanwhile promoted the formation of weak acid sites, which had a positive effect on the synthesis of alcohol. Furthermore, it was found that the incorporation of Mn can enhance the adsorption of linear- and bridge-type CO significantly, which contributed to the formation of alcohol and growth of carbon chain and thus increased the selectivity to C2＋OH.
基金supported by the National Natural Science Foundation of China (21275136)the Natural Science Foundation of Jilin Province (201215090)
文摘Fe3C-functionalized three-dimensional （3D） porous nitrogen-doped graphite carbon composites （Fe3C/ NG） were synthesized via a facile solution-based impreg- nation and pyrolysis strategy using the commercially available melamine foam and FeC13 as precursors. The structural characterizations confirmed that Fe3C nanoparticles with an average core size about 122 nm were assembled on the surface of the carbonized melamine foam （CMF） skeletons. The electrochemical measurements demonstrated the superior electrocatalytic activity of the advanced Fe3C/NG composite for hydrogen peroxide reduction reaction in 0.1 mol/L PBS electrolyte and the limit of detection of H2O2 is estimated to be 0.035 mmol/L at a signal-to-noise ratio of 3 with a wide linear detection range from 50 μmol/L to 15 mmol/L （R^2 = 0.999）. Compared with the pure CMF, the Fe3C/NG exhibited higher catalytic activity, more stable response, lower detection limit, higher selectivity and a wider detection range, which could be attributed to the synergic effect between the two types of active sites from the iron carbide species and the nitrogen-doped graphite carbon. Meanwhile, the large surface area, high conductivity and the improved mass transport from the 3D porous material can also promote the electrochemical sensing performance. Moreover, the Fe3C/ NG-based electrochemical sensor showed high anti-interference ability and stability for H2O2 detection. Thus, the novel and low-cost Fe3C/NG composite may be a prom- ising alternative to noble metals and offer potential appli- cations in various types of electrochemical sensors, bioelectronic devices and catalysts.
