As a kind of metal-free material, graphitic carbon nitride (g-C3N4) is widely used in catalytic materials, energy storage materials and other fields. However, the limited light absorption, low ...conductivity and high recombination rate of the photogenerated electron–hole pairs limit its further application. Constructing g-C3N4 based composite materials by integrating it with carbon materials is an effective and common way to overcome the above shortcomings of g-C3N4. In this paper, carbon materials, such as carbon dots, carbon nanotubes, graphene, and carbon spheres, are integrated with g-C3N4 to construct carbon/g-C3N4 composite materials (CCNCS) and their photoelectrocatalytic performance is reviewed. The effects of those factors such as the categories of carbon materials, carbon content, nitrogen content, the morphology of g-C3N4, and the interfacial interactions between carbon and g-C3N4 on the photo/electrocatalytic performance of CCNCS are carefully analyzed to help researchers to touch the nature of the synergistic effect of g-C3N4 and the carbon ingredient in CCNCS.
In this article, we consider a renewal risk model with by-claims, where the price process of the investment portfolio follows an exponential Lévy process. We further assume that the main claim is a ...one-sided linear process and there exists a certain dependence structure between the innovations and by-claims. In the presence of heavy tails, we obtain a series of uniform formulas in finite and infinite intervals. In order to better describe the obtained results, we carry on the numerical simulations.
Full text
Available for:
BFBNIB, GIS, IJS, KISLJ, NUK, PNG, UL, UM, UPUK
As a kind of metal-free material, graphitic carbon nitride (g-C
N
) is widely used in catalytic materials, energy storage materials and other fields. However, the limited light absorption, low ...conductivity and high recombination rate of the photogenerated electron-hole pairs limit its further application. Constructing g-C
N
based composite materials by integrating it with carbon materials is an effective and common way to overcome the above shortcomings of g-C
N
. In this paper, carbon materials, such as carbon dots, carbon nanotubes, graphene, and carbon spheres, are integrated with g-C
N
to construct carbon/g-C
N
composite materials (CCNCS) and their photoelectrocatalytic performance is reviewed. The effects of those factors such as the categories of carbon materials, carbon content, nitrogen content, the morphology of g-C
N
, and the interfacial interactions between carbon and g-C
N
on the photo/electrocatalytic performance of CCNCS are carefully analyzed to help researchers to touch the nature of the synergistic effect of g-C
N
and the carbon ingredient in CCNCS.
As a kind of metal-free material, graphitic carbon nitride (g-C
3
N
4
) is widely used in catalytic materials, energy storage materials and other fields. However, the limited light absorption, low ...conductivity and high recombination rate of the photogenerated electron-hole pairs limit its further application. Constructing g-C
3
N
4
based composite materials by integrating it with carbon materials is an effective and common way to overcome the above shortcomings of g-C
3
N
4
. In this paper, carbon materials, such as carbon dots, carbon nanotubes, graphene, and carbon spheres, are integrated with g-C
3
N
4
to construct carbon/g-C
3
N
4
composite materials (CCNCS) and their photoelectrocatalytic performance is reviewed. The effects of those factors such as the categories of carbon materials, carbon content, nitrogen content, the morphology of g-C
3
N
4
, and the interfacial interactions between carbon and g-C
3
N
4
on the photo/electrocatalytic performance of CCNCS are carefully analyzed to help researchers to touch the nature of the synergistic effect of g-C
3
N
4
and the carbon ingredient in CCNCS.
As a kind of metal-free material, graphitic carbon nitride (g-C
3
N
4
) is widely used in catalytic materials, energy storage materials and other fields.
Display omitted
•Au-Pd alloy particles supported on/SiO2 with different surface structures were prepared.•Few synergetic effect of Au-Pd alloy occurs on catalyzing CO oxidation.•Alloying Au with Pd ...reduces the intrinsic activity in catalyzing CO oxidation.•Contiguous Pd atoms on Au-Pd alloy are active in catalyzing CO oxidation while isolated Pd atoms are not.
Various Au-Pd/SiO2 catalysts with a fixed Au loading but different Au:Pd molar ratios were prepared via deposition-precipitation method followed by H2 reduction. The structures were characterized and the catalytic activities in CO oxidation were evaluated. The formation of Au-Pd alloy particles was identified. The Au-Pd alloy particles exhibit enhanced dispersions on SiO2 than Au particles. Charge transfer from Pd to Au within Au-Pd alloy particles. Isolated Pd atoms dominate the surface of Au-Pd alloy particles with large Au:Pd molar ratios while contiguous Pd atoms dominate the surface of Au-Pd alloy particles with small Au:Pd molar ratios. Few synergetic effect of Au-Pd alloy occurs on catalyzing CO oxidation under employed reaction conditions. Alloying Au with Pd reduces the intrinsic activity in catalyzing CO oxidation, and contiguous Pd atoms on the Au-Pd alloy particles are capable of catalyzing CO oxidation while isolated Pd atoms are not. These results advance the fundamental understandings of Au-Pd alloy surfaces in catalyzing CO oxidation.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Display omitted
•A new understanding in the active site of CuMnOx catalysts.•CuMnOx catalysts are composed by uniform CuO-Mn2O3 oxide pairs.•Highly isolated CuO nano-particles are essential for ...CuO-Mn2O3 oxide pairs.•Cu-O-Mn sites are found to be the active sites of CuO-Mn2O3 oxide pairs.
The current work provide a new understanding on the active site of CuMnOx catalysts and thus offer a new perspective in the development of highly effective and low cost CuMnOx catalysts for heterogeneous catalytic oxidation reactions. A series of dual-component copper-manganese multi-oxide catalysts (CuMnOx) have been successfully synthesized using a surfactant assisted hydrolysis-hydrothermal method and studied by XRD, N2 adsorption–desorption test, ICP-AES, SEM, Aberration-corrected HADDF-STEM, HRTEM, FT-IR, Raman, XPS, H2-TPR. These CuMnOx catalysts were found to be composed with uniform CuO-Mn2O3 oxide pair structure, in which highly isolated/dispersed CuO species are anchored in the framework of Mn2O3. It was found that the speciation in these CuMnOx catalysts presents a shift from highly isolated or even single Cu2+ oxide species (Cu2+Ox) to CuO nanoclusters and CuO microcrystalline with increasing Cu content. In CO oxidation reaction, which was employed to probe the structure of the CuO-Mn2O3 oxide pairs in these CuMnOx catalysts, the Cu-O-Mn sites in those CuMnOx catalysts with highly isolated or highly dispersed CuO species were found to be highly active. For CuO-Mn2O3 oxide pair catalysts, the highly isolated/dispersed CuO species in Mn2O3 framework is essential to achieve high activity.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Consider a discrete-time risk model with dependence structures, where claim sizes are assumed to follow a one-sided linear process whose innovations further obey a so-called bivariate upper tail ...independence. The stochastic discount factors follow a stationary causal process. Then, the insurer is said to be exposed to a stochastic economic environment that contains two kinds of risks, i.e. the insurance risk and financial risk. The two kinds of risks form a sequence of independent and identically distributed random pairs which are copies of a random pair with a common bivariate Sarmanov dependent distribution. When the distributions of the innovations belong to the intersection of the dominated-variation class and the long-tailed class, we derive some asymptotic formulas for the finite-time ruin probability. We also get conservative asymptotic bounds when the distributions of the innovations belong to the regular variation class. Finally, we verify our results through a Crude Monte Carlo simulation.
Full text
Available for:
BFBNIB, GIS, IJS, KISLJ, NUK, PNG, UL, UM, UPUK
We report a detailed investigation of the behavior of chemisorbed hydrogen atoms (H
a
) on Pt(111) by a combination of an experimental study of the H
a
+ D
a
reaction and first-principles ...calculations. The coverage-dependent adsorption and desorption behavior of H
a
and D
a
on Pt(111) have been systematically established and can be well interpreted in terms of repulsive interactions between adsorbates. H
a
adsorbs exclusively on the face-centered cubic (fcc) sites of Pt(111) at coverages not exceeding 1 monolayer (ML). With increasing H
a
coverage, repulsive interactions between H
a
increase, leading to a reduction in both the adsorption energy and the desorption activation energy. It is proposed that the lateral interactions within a H
a
layer are partly induced by the local repulsive interactions due to high mobility of H
a
on Pt(111). For the H
a
+ D
a
exchange reaction on Pt(111), it is found that Ha has a higher selectivity for HD formation than D
a
. Considering that H
a
diffuses much faster than D
a
on Pt(111), we propose that the difference in diffusion rates between H
a
and D
a
may determine the selectivity of H
a
and D
a
in forming HD in the H
a
+ D
a
reaction on Pt(111).
Full text
Available for:
EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The selective oxidation of propylene with O2 to propylene oxide and acrolein is of great interest and importance. We report the crystal‐plane‐controlled selectivity of uniform capping‐ligand‐free ...Cu2O octahedra, cubes, and rhombic dodecahedra in catalyzing propylene oxidation with O2: Cu2O octahedra exposing {111} crystal planes are most selective for acrolein; Cu2O cubes exposing {100} crystal planes are most selective for CO2; Cu2O rhombic dodecahedra exposing {110} crystal planes are most selective for propylene oxide. One‐coordinated Cu on Cu2O(111), three‐coordinated O on Cu2O(110), and two‐coordinated O on Cu2O(100) were identified as the catalytically active sites for the production of acrolein, propylene oxide, and CO2, respectively. These results reveal that crystal‐plane engineering of oxide catalysts could be a useful strategy for developing selective catalysts and for gaining fundamental understanding of complex heterogeneous catalytic reactions at the molecular level.
Just plane favoritism: In the catalysis of propylene oxidation with O2 to acrolein, propylene oxide, and CO2, Cu2O octahedra with exposed {111} crystal planes favored the formation of acrolein, Cu2O cubes with exposed {100} crystal planes gave CO2 preferentially, and Cu2O rhombic dodecahedra with exposed {110} crystal planes gave a higher proportion of propylene oxide. The active sites for these reactions were identified as indicated in the scheme.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
By rational design of the FeO(111)/Pt(111) inverse model catalyst and the control experiments, we report for the first time direct experimental evidence for the interfacial COads + OHads reaction to ...produce CO2 at the Pt−oxide interface at low temperatures, providing deep insights into the reaction mechanism and active site of the important low-temperature water-gas shift and preferential CO oxidation reactions catalyzed by Pt/oxide nanocatalysts at the molecular level.
Full text
Available for:
IJS, KILJ, NUK, PNG, UL, UM
