Photocatalysis,which is the catalyzation of redox reactions via the use of energy obtained from light sources,is a topic that has garnered a lot of attention in recent years as a means of addressing the environmental and economic issues plaguing society today.Of particular interest are photosynthesis can potentially mimic a variety of vital reactions,many of which hold the key to develop sustainable energy economy.In light of this,many of the technological and procedural advancements that have recently occurred in the field are discussed in this review,namely those linked to:(1)photocatalysts made from metal oxides,nitride,and sulfides;(2)photocatalysis via polymeric carbon nitride(PCN);and(3)general advances and mechanistic insights related to TiO2-based catalysts.The challenges and opportunities that have arisen over the past few years are discussed in detail.Basic concepts and experimental procedures which could be useful for eventually overcoming the problems associated with photocatalysis are presented herein. 相似文献
Using Brownian dynamics simulations, we study the effect of the charge ratio, the surfactant length, and the grafting density
on the conformational behavior of the complex formed by the polyelectrolyte brush with oppositely charged surfactants. In
our simulations, the polyelectrolyte chains and surfactants are represented by a coarse-grained bead-spring model, and the
solvent is treated implicitly. It is found that varying the charge ratio induces different morphologies of surfactant aggregates
adsorbed onto the brush. At high charge ratios, the density profiles of surfactant monomers indicate that surfactant aggregates
exhibit a layer-by-layer arrangement. The surfactant length has a strong effect on the adsorption behavior of surfactants.
The lengthening of surfactant leads to a collapsed brush configuration, but a reswelling of the brush with further increasing
the surfactant length is observed. The collapse of the brush is attributed to the enhancement of surfactants binding to polyelectrolyte
chains. The reswelling is due to an increase in the volume of adsorbed surfactant aggregates. At the largest grafting density
investigated, enhanced excluded volume interactions limit the adsorption of surfactant within the polyelectrolyte brush. We
also find that end monomers in polyelectrolyte chains exhibit a bimodal distribution in cases of large surfactant lengths
and high charge ratios. 相似文献
In this paper, a single reaction-diffusion population model with memory effect and the heterogeneity of the environment, equipped with the Neumann boundary, is considered. The global existence of a spatial nonhomogeneous steady state is proved by the method of super and subsolutions, which is linearly stable for relatively small memory-induced diffusion. However, after the memory-induced diffusion rate exceeding a critical value, spatial inhomogeneous periodic solution can be generated through Hopf bifurcation, if the integral of intrinsic growth rate over the domain is negative. Such phenomenon will never happen, if only memory-induced diffusion or spatially heterogeneity is presented, and therefore must be induced by their joint effects. This indicates that the memory-induced diffusion will bring about spatial-temporal patterns in the overall hostile environment. When the integral of intrinsic growth rate over the domain is positive, it turns out that the steady state is still linearly stable. Finally, the possible dynamics of the model is also discussed, if the boundary condition is replaced by Dirichlet condition.
Based on the fibrous silicates (palygorskite, PT) organically modified by water-soluble polyvinylpyrrolidone (PVP), poly(ethylene terephthalate) (PET) nanocomposite with good dispersion of the PT nano-particles was prepared via in situ polycondensation. The thermal degradation behavior of PET and PET/PT nanocomposite was investigated by thermogravimetric analysis (TGA) under non-isothermal conditions at various heating rates in air and nitrogen, respectively. The apparent activation energies of the samples were evaluated by Kissinger and Flynn-Wall-Ozawa method. It is suggested that, during thermal decomposition in nitrogen, the clay as a mass-transport protective barrier can slow down degradation of polymer, but the catalytic effect of metal derivatives in clays may accelerate the decomposition behavior of PET. The combination of these two effects determines the final thermal stability of nanocomposite. However, in air atmosphere, the oxidative thermal stability of PET/PT nanocomposite was obviously superior to that of pure PET. 相似文献
Reactions of one or two equiv. of cyclohexyl isocyanide in THF at room temperature with Mo?Mo triply bonded complexes [Mo(CO)2(η5‐C5H4R)]2 (R=COCH3, CO2CH3) gave the isocyanide coordinated Mo? Mo singly bonded complexes with functionally substituted cyclopentadienyl ligands, [Mo(CO)2(η5‐C5H4R)]2(μ‐η2‐CNC6H11) ( 1a , R=COCH3; 1b , R=CO2CH3) and [Mo(CO)2(η5‐C5H4R)(CNC6H11)]2 ( 2a , R=COCH3; 2b , R=CO2CH3), respectively. Complexes 1a , 1b and 2a , 2b could be more conveniently prepared by thermal decarbonylation of Mo? Mo singly bonded complexes [Mo(CO)3(η5‐C5H4R)]2 (R=COCH3, CO2CH3) in toluene at reflux, followed by treatment of the resulting Mo?Mo triply bonded complexes [Mo(CO)2(η5‐C5H4R)]2 (R=COCH3, CO2CH3) in situ with cyclohexyl isocyanide. While 1a , 1b and 2a , 2b were characterized by elemental analysis and spectroscopy, 1b was further characterized by X‐ray crystallography. 相似文献