Institutional Repository of Dalian Institute of Chemical Physics, CAS
Not a member yet
45557 research outputs found
Sort by
High Resolution Crossed Molecular Beams Study of the H+HD -> H-2+D Reaction
No full textThe H+H-2 reaction is the simplest chemical reaction system and has long been the prototype model in the study of reaction dynamics. Here we report a high resolution experimental investigation of the state-to-state reaction dynamics in the H+HD -> H-2+D reaction by using the crossed molecular beams method and velocity map ion imaging technique at the collision energy of 1.17 eV. D atom products in this reaction were probed by the near threshold 1+1'(vacuum ultraviolet+ultraviolet) laser ionization scheme. The ion image with both high angular and energy resolution were acquired. State-to-state differential cross sections was accurately derived. Fast forward scattering oscillations, relating with interference effects in the scattering process, were clearly observed for H-2 products at H-2(v'=0, j'=1) and H-2(v'=0, j'=3) rovibrational levels. This study further demonstrates the importance of measuring high-resolution differential cross sections in the study of state-to-state reaction dynamics in the gas phase
Efficient oxygen reduction reaction catalyst derived from ZnO@ zeolite imidazolate framework nanowire composite
No full textThe oxygen reduction reaction (ORR) is one of the core reactions that occur in fuel cells and metal air batteries. Metal-free catalysts such as porous carbons are promising candidates for ORR and the performance of porous carbons strongly depends on their nanostructure. Herein, we reported the synthesis of high surface area N doped carbon nanotube (CNT-900) by using ZnO@zeolite imidazolate framework (ZnO@ZIF-8) nanowire as a precursor. When used for an ORR catalyst, the CNT-900 show obvious superior performance compared with the carbon derived from ZIF-8. In addition, it exhibits comparable activity with 20 wt% Pt/C and superior stability. Combined with green and facile synthesis strategy, the method in this work can be easily extended to synthesis other nanomaterials for energy storage and conversion application
Structural Insights into Phosphite Dehydrogenase Variants Favoring a Non-natural Redox Cofactor
No full textImplementation of a non-natural cofactor alternative to the ubiquitous redox cofactor nicotinamide adenosine dinucleotide (NAD) is of great scientific and biotechnological interest. Several redox enzymes have been engineered to favor nicotinamide cytosine dinucleotide (NCD), a smaller-sized NAD analogue. However, molecular interactions involving NAD analogues remain elusive, preventing us from devising more enzymes to accept those analogues. Here we took a semirational approach to evolve phosphite dehydrogenase (Pdh) and identified variants with substantially improved NCD preference. These mutants are valuable components for regeneration of reduced NCD by using phosphite as the electron donor. We then collected X-ray crystal structures of three Pdh variants and their NCD-complexes to delineate molecular basis for NCD binding. It was found that the incorporation of amino acid residues with large side chains enclosing the NAD-binding pocket led to compacted environment favoring NCD over NAD, and additional interactions between NCD and these side chains. These results guided successful engineering of more Pdh mutants with good NCD preference. As many redox enzymes share key structural features, our strategy may be readily adopted to devise NCD-favoring enzymes. We expected that, in the near future, more synthetic systems linked to non-natural cofactors will be created as alternative tools for widespread applications to address challenging problems by chemical and synthetic biologists
National Institute of General Medical Sciences-NIGMS from the National Institutes of Health[5 P30 GM110758-02]
No full textInvestigation on the reaction area of PEMFC at different position in multiple catalyst layer
No full textTo study the oxygen reduction reaction (ORR) at different through-plane position in catalyst layer, a multiple catalyst layer (MCL) was designed in which the reaction area could move from proton exchange membrane (PEM) to gas diffusion layer (GDL). The reaction layer (layer Y) was sandwiched between proton conduct layer (layer X) and air diffusion layer (layer Z) to simulate the real reacting process in an ordinary catalyst layer. Three MEA samples with MCL were made, the reaction area was set near the PEM, in the middle of catalyst layer and near the GDL, respectively. According to the polarization curves, the position of reaction area in catalyst layer has obvious influence on cell performance and the output current at the same working voltage increased when the reaction area moved towards GDL. Besides, how the charge transfer resistance and mass transport resistance of reaction area at different position in CL changed when output current increased has also been studied in this work using EIS. Simulation results about current and proton distribution have also been verified in this work. (C) 2019 Elsevier Ltd. All rights reserved
