Robust tuning metal/carbon heterointerfaces via ketonic oxygen enables hydrogen evolution reaction outperforming Pt/C

Large-scale synthesis of metal/carbon hybrids with tunable metal/carbon heterointerfaces is vital for practical application of such hybrids in electrocatalysis. Herein, we developed a facile route for large-scale crafting of ultrafine Ru nanoparticles (NPs) anchored on the ketonic C[dbnd]O groups of carbon nanotubes (CNTs) (9.6 g in one batch). From both experimental results and theoretical calculations, we demonstrate that C[dbnd]O (rather than C\u2013O) groups can be exploited to engineer the heterointerface of CNTs and Ru NPs. In fact, the electronic structure of Ru becomes considerably improved because the high polarity of C[dbnd]O facilitates the interface electron transfer of Ru/CNTs. Consequently, the obtained Ru-O-CNTs hybrids with low Ru loading of 1.5 wt% display a small overpotential of 25 mV at 10 mA cm 122 and with fast kinetics as deduced from a small Tafel slope of 20.4 mV dec 121 for hydrogen evolution reaction (HER) in 1 M KOH. Impressively, at 70 mV overpotential, the hybrids exhibit a record mass activity of 20.4 mA \u3bcg 121Ru, which is more than 50-fold of that for commercial Pt/C. Therefore, for the first time, we identified the vital role of C[dbnd]O groups for engineering metal/carbon heterointerfaces towards robust and efficient electrocatalysis. \ua9 202

Electrochemical and computational studies on intramolecular dissociative electron transfer in beta-peptides

The preparation of the β-peptides PCB-β3Val- β3Ala-β3Leu-NHC(CH3) 2OOtBu and PCB-(β3Val-β3Ala- β3Leu)2-NHC(CH3)2OOtBu, with a specific donor and acceptor at each terminus, is described. Circular dichroism, 2D NMR, and density functional theory calculations confirmed that PCB-(β3Val-β3Ala-β3Leu) 2-NHC(CH3)2OOtBu adopts a 14-helix conformation, whereas PCB-β3Val-β3Ala- β3Leu-NHC(CH3)2OOtBu has an ill-defined secondary structure. The electron-transfer rate constants in the two peptides were found to be 2580 and 9.8 s-1 respectively. Computational simulations based on Marcus theory coupled to constrained density functional theory provide clear theoretical evidence that different electron-transport pathways occur in the two peptides due to their different conformations: sequential hopping within PCB-(β3Val-β3Ala- β3Leu)2-NHC(CH3)2OOtBu and superexchange within PCB-β3Val-β3Ala- β3Leu-NHC(CH3)2OOtBu. Electron population analysis provides the first clear theoretical evidence that amide groups can act as hopping sites in long-range electron transfer. © 2012 American Chemical Society.Jingxian Yu, David M. Huang, Joe G. Shapter, and Andrew D. Abel