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71.
A natural and artificial distribution of electron transfer activity on glassy carbon electrodes can be observed and quantified
by the use of scanning electrochemical microscopy (SECM). A large (sevenfold) spread in rate constant is found for randomly
sampled sites on polished, untreated glassy carbon surfaces. Direct-mode oxidation with the SECM tip was used to produce small
regions of oxidized carbon on a polished surface. A large increase in electron transfer rate for the Fe(II/III) ion is observed
on the locally oxidized carbon surface in comparison to the unoxidized region. Rate constant measurements made along a line
profiles the transition from unoxidized to oxidized surfaces. SECM images of defect sites show reaction–rate variations. Rate
constants measured at several locations of the defective surface allows discrimination between the kinetic and topographic
components of the SECM image.
Dedicated to the 80th birthday of Keith B. Oldham 相似文献
72.
Holger Ott Christoph Matthes Dr. Arne Ringe Dr. Jörg Magull Prof. Dr. Dietmar Stalke Prof. Dr. Uwe Klingebiel Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(18):4602-4609
Borenes and boranes : Silylaminoiminoborenes, such as depicted, were isolated after treatment of halogen triels with silylaminofluoroboranes. In addition, novel aryl‐ and silyl‐substituted diaminofluoroboranes were also prepared in order to substantiate this reaction route.
73.
通过简单的钴铁前躯体热分解法制备了系列一维Co1-xFexOy(0≤x≤1)多孔纳米材料,并在1 mol·L-1 KOH溶液中研究了其电解水析氧催化性能。研究发现不同Fe掺杂量对材料的结构与电解水析氧催化性能有较大的影响,其中16%(n/n)Fe掺杂量的Co1-xFexOy具有最优的析氧催化性能。在10 mA·cm-2电流密度下其析氧过电位为345 mV,塔菲尔斜率为54 mV·dec-1,并表现出优异的析氧稳定性能。廉价、高效的Co1-xFexOy多孔纳米棒材料有望成为优良的析氧催化剂用于电解水制氢。 相似文献
74.
Michael Dolg 《Theoretical chemistry accounts》2005,114(4-5):297-304
Energy-consistent relativistic pseudopotentials for 3d-transition metals Sc to Ni based on modified valence energies are proposed. The pseudopotentials are adjusted at the finite
difference level within the intermediate coupling scheme with respect to multi-configuration Dirac–Hartree–Fock data based
on the Dirac–Coulomb Hamiltonian with an estimate of the Breit contributions in quasidegenerate perturbation theory. Typically
a few hundred to thousand J levels arising from about 35 to 40 configurations ranging from the anion down to the highly charged
cation are considered as references. It is shown that introducing a small common energetic shift of all valence energies reduces
the errors in the parameter adjustment considerably. Results of highly correlated atomic and molecular test calculations using
large basis sets and basis set extrapolation techniques are presented.
To be submitted to Theoretical Chemistry Accounts (special volume on the occasion of Prof. Dr. H. Stoll's 60th birthday) 相似文献
75.
Substitution of Fe for Sc in CoFe2O4 spinel structure is presented. All CoFe2−xScxO4 compounds crystallize in the spinel type structure (space group Fd3?m). By using X-ray diffraction studies, magnetic measurements and in-field 57Fe Mössbauer spectrometry, the limit of substitution has been determined to be equal to x=0.56. An increase in the cell parameter and the strains and a decrease in the apparent crystallites size are observed. For x>0.3, a partial oxidation of cobalt is evidenced and Co3+ is stabilized in the structure. A ferromagnetic behavior has been observed for all investigated compounds. As x increases, the Curie temperature and the hyperfine fields decrease. Following the Stephenson model, the diminution of TC is ascribed to a decrease of the main JAB interaction. 相似文献
76.
Kang IJ Khan NA Haque E Jhung SH 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(23):6437-6442
Chemical and thermal stabilities of isotypic metal-organic frameworks (MOFs) like Al-BDC (Al-benzenedicarboxylate called MIL-53-Al), Cr-BDC (MIL-53-Cr) and V-BDC (MIL-47-V), after purification to remove uncoordinated organic linkers, have been compared to understand the effect of the central metal ions on the stabilities of the porous MOF-type materials. Chemical stability to acids, bases, and water decreases in the order of Cr-BDC>Al-BDC>V-BDC, suggesting stability increases with increasing inertness of the central metal ions. However, thermal stability decreases in the order of Al-BDC>Cr-BDC> V-BDC, and this tendency may be explained by the strength of the metal-oxygen bond in common oxides like Al(2)O(3), Cr(2)O(3), and V(2)O(5). In order to evaluate precisely the stability of a MOF, it is necessary to remove uncoordinated organic linkers that are located in the pores of the MOF, because a filled MOF may be more stable than the same MOF after purification. 相似文献
77.
78.
79.
《Acta Crystallographica. Section C, Structural Chemistry》2018,74(2):236-239
The crystal structure of Ce0.8Gd0.1Ho0.1O1.9 (cerium gadolinium holmium oxide) has been determined from powder X‐ray diffraction data. This is a promising material for application as a solid electrolyte for intermediate‐temperature solid oxide fuel cells (IT‐SOFCs). Nanoparticles were prepared using a novel sodium alginate sol‐gel method, where the sodium ion was exchanged with ions of interest and, after washing, the gel was calcined at 723 K in air. The crystallographic features of Gd and Ho co‐doped cerium oxide were investigated around the desired operating temperatures of IT‐SOFCs, i.e. 573 ≤ T ≤ 1023 K. We find that the crystal structure is a stable fluorite structure with the space group Fmm in the entire temperature range. In addition, the trend in lattice parameters shows that there is a monotonic increase with increasing temperature. 相似文献
80.
The Structure of the Cobalt Oxide/Au Catalyst Interface in Electrochemical Water Splitting 下载免费PDF全文