Synergistic effect between few layer graphene and carbon nanotube supports for palladium catalyzing electrochemical oxidation of alcohols

Few layer graphene （FLG）, multi-walled carbon nanotubes （CNTs） and a nanotube-graphene composite （CNT-FLG） were used as supports for palladium nanoparticles. The catalysts, which were characterized by transmission electron microscopy, Raman spectroscopy and X-ray diffraction, were used as anodes in the electrooxidation of ethanol, ethylene glycol and glycerol in half cells and in passive direct ethanol fuel cells. Upon Pd deposition, a stronger interaction was found to occur between the metal and the nanotube-graphene composite and the particle size was significantly smaller in this material （6.3 nm）, comparing with nanotubes and graphene alone （8 and 8.4 nm, respectively）. Cyclic voltammetry experiments conducted with Pd/CNT, Pd/FLG and Pd/CNT-FLG in 10 wt% ethanol and 2 M KOH solution, showed high specific currents of 1.48, 2.29 and 2.51 mA-/zgp-d, respectively. Moreover, the results obtained for ethylene glycol and glycerol oxidation highlighted the excellent electrocatalytic activity of Pd/CNT-FLG in terms of peak current density （up to 3.70 mAgd for ethylene glycol and 1.84 mAfor glycerol, respectively）. Accordingly, Pd/CNT-FLG can be considered as the best performing one among the electrocatalysts ever reported for ethylene glycol oxidation, especially considering the low metal loading used in this work. Direct ethanol fuel cells at room temperature were studied by obtaining power density curves and undertaking galvanostatic experiments. The power density outputs using Pd/CNT, Pd/FLG and Pd/CNT-FLG were 12.1, 16.3 and 18.4 mW.cm-2, respectively. A remarkable activity for ethanol electrooxidation was shown by Pd/CNT-FLG anode catalyst. In a constant current experiment, the direct ethanol fuel cell containing Pd/CNT-FLG could continuously deliver 20 mA.cm-2 for 9.5 h during the conversion of ethanol into acetate of 30%, and the energy released from the cell was about 574 J.

Efficient hexane isomers separation in isoreticular bipyrazolate metal-organic frameworks:The role of pore functionalization

Hydrocarbons separation in petrochemical industries is a key,energy-consuming stage in the manufacture of high-quality added-value products—hence the need for more efficient materials and environmentally friendly methodologies to improve this process.In this context,we have studied the effect of metal-organic frameworks(MOFs)pore functionalization in hexane isomers separation,isolating the robust isoreticular zinc(ll)bipyrazolates Zn(BPZ),showing no pore decoration,Zn(Me_(2)BPZ),the pores of which are decorated with apolar methyl groups,and Zn(BPZ(NH_(2))_(2)),the spacers of which possess polar Lewis-basic functions(H_(2)BPZ=1H,1'H-4,4'-bipyrazole;H_(2)Me_(2)BPZ=3,3'-dimethyl-1H,1'H-4,4'-bipyrazole;H_(2)BPZ(NH_(2))_(2)=3,5-diamino-1H,1'H-4,4'-bipyrazole;DMF=dimethylformamide).After characterizing Zn(BPZ(NH_(2))_(2))as per its crystal structure and thermal behaviour,and all the three MOFs as per their textural properties,we investigated,from the experimental and computational points of view,the impact of the square one-dimensional channels decoration on the separation of the hexane isomers,demonstrating the relevance of pore constrictions in the resolution of the title alkanes mixture.