Formic acid (HCOOH) has a great potential as a safe and a convenient hydrogen carrier for fuel cell applications. However, efficient and CO-free hydrogen production through the decomposition of formic acid at low temperatures (<363 K) in the absence of additives constitutes a major challenge. Herein, we present a new heterogeneous catalyst system composed of bimetallic PdAg alloy and MnO x nanoparticles supported on amine-grafted silica facilitating the liberation of hydrogen at room temperature through the dehydrogenation of formic acid in the absence of any additives with remarkable activity (330 mol H 2 ·mol catalyst −1 ·h −1 ) and selectivity (>99%) at complete conversion (>99%). Moreover this new catalytic system enables facile catalyst recovery and very high stability against agglomeration, leaching, and CO poisoning. Through a comprehensive set of structural and functional characterization experiments, mechanistic origins of the unusually high catalytic activity, selectivity, and stability of this unique catalytic system are elucidated. Current heterogeneous catalytic architecture presents itself as an excellent contender for clean hydrogen production via room-temperature additive-free dehydrogenation of formic acid for on-board hydrogen fuel cell applications.

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Two allosteric models are presented for theT*-»R transition of insulin hexamers in the presence of phenolic ligands which are based on existing experimental information. The transition mainly involves residues 1-8 of the B-chain, i.e. 15% of the molecule, which are extended in the T-and helical in the R-state. The main facts to be accounted for are: 1) the transition is undergone trimer-wise; 2) the transition of the second trimer is disadvantaged compared to the first one; 3) the subunits of a trimer undergo transition in a cooperative process; 4) binding sites for phenolic ligands only exist in R 3 trimers; 5) ligands shift the equilibrium by arresting the R-state; 6) the ligand is accommodated in a pocket made up between two adjacent subunits; 7) binding one ligand molecule extends the lifetime of the two other binding sites of a trimer; 8) only ligand-free trimers can undergo transitions. The two models allowed for CD spectroscopic titrations of zinc and cobalt insulin with phenol and -cresol to be assessed in terms of structural reorganisation and ligand binding, and for the respective standard free energy differences to be calculated. AG° for the reorganisation of the first trimer in zincinsulin is about 8kJ/mol, and for that of the second trimer, 21kJ/mol. The corresponding values for cobalt-insulin are 12 and 24kJ/mol, respectively. For both zinc-and cobalt-insulin, the AG° for phenol and m-cresol binding is about -18kJ/mol. Both models are equally compatible with the titration data.

Herein, we report the preparation and characterization of platinum(0) nanoparticles stabilized by amylamine (C 5 H 11 NH 2 ) ligands plus their catalytic use in the room temperature dehydrocoupling of dimethylamineborane ((CH 3 ) 2 NHBH 3 ), which has attracted recent attention as a promising solid hydrogen storage material. Amylamine stabilized platinum(0) nanoparticles were reproducibly generated by an ethanolsuperhydride reduction method and their preliminary characterization was done by ICP-OES, XRD, ATR-IR, TEM, HRTEM, and XPS spectroscopies. The sum of their results shows the formation of highly crystalline and colloidally stable platinum(0) nanoparticles. The catalytic performance of these new platinum(0) nanoparticles in terms of activity, isolability and reusability was investigated in the catalytic dehydrocoupling of dimethylamine-borane, in which they were found to be active and reusable heterogeneous catalysts even at room temperature.Scheme 1 The catalytic dehydrogenation/dehydrocoupling of dimethylamine-borane ((CH 3 ) 2 NHBH 3 , DMAB).