Ultralow-Energy-Barrier H_(2)O_(2)Dissociation on Coordinatively Unsaturated Metal Centers in Binary Ce-Fe Prussian Blue Analogue for Efficient and Stable Photo-Fenton Catalysis

The low intrinsic activity of Fenton catalytic site and high demand for light-energy input inhibit the organic-pollution control efficiency of photo-Fenton process.Here,through structural design with density functional theory(DFT)calculations,Ce is predicted to enable the construction of coordinatively unsaturated metal centers(CUCs)in Prussian blue analogue(PBA),which can strongly adsorb H_(2)O_(2)and donate sufficient electrons for directly splitting the O-O bond to produceOH.Using a substitution-co-assembly strategy,binary Ce-Fe PBA is then prepared,which rapidly degrades sulfamethoxazole with the pseudo-first-order kinetic rate constant exceeding reported values by 1-2 orders of magnitude.Meanwhile,the photogenerated electrons reduce Fe(Ⅲ)and Ce(Ⅳ)to promote the metal valence cycle in CUCs and make sulfamethoxazole degradation efficiency only lose 6.04%in 5 runs.Overall,by introducing rare earth metals into transition metal-organic frameworks,this work guides the whole process for highly active CUCs from design and construction to mechanism exploration with DFT calculations,enabling ultrafast and stable photo-Fenton catalysis.

Discovery of Two Families of VSb-Based Compounds with V-Kagome Lattice

We report the structure and physical properties of two newly discovered compounds AV_(8)Sb_(12)and AV_(6)Sb_(6)(A=Cs,Rb),which have C_(2)(space group:Cmmm)and C_(3)(space group:R3 m)symmetry,respectively.The basic Vkagome unit appears in both compounds,but stacking differently.AV_(2)Sb_(2) layer is sandwiched between two V_(3)Sb_(5)layers in AV_(8)Sb_(12),altering the V-kagome lattice and lowering the symmetry of kagome layer from hexagonal to orthorhombic.In AV_(6)Sb_(6),the building block is a more complex slab made up of two half-V_(3)Sb_(5)layers that are intercalated by Cs cations along the c-axis.Transport property measurements demonstrate that both compounds are nonmagnetic metals,with carrier concentrations at around 10^(21)cm^(-3).No superconductivity has been observed in CsV_(8)Sb_(12)above 0.3 K under in situ pressure up to 46 GPa.Compared to CSV_(3)Sb_(5),theoretical calculations and angle-resolved photoemission spectroscopy reveal a quasi-two-dimensional electronic structure in CsV_(8)Sb_(12)with C_(2)symmetry and no van Hove singularities near the Fermi level.Our findings will stimulate more research into V-based kagome quantum materials.

Efficiency evaluation of government investment for air pollution control in city clusters:A case from the Beijing-Tianjin-Hebei areas in China

Air pollution poses a significant threat to human health,particularly in urban areas with high levels of industrial activities.In China,the government plays a crucial role in managing air quality through the Air Pollution Prevention and Control Action Plan.The government provides direct financial support and guides the investment direction of social funds to improve air quality.While government investment has led to improvements in air quality across China,concerns remain regarding the efficiency of such large-scale investments.To address this concern,we conducted a study using a three-stage data envelopment analysis(DEA)-Malmquist model to assess the efficiency of government investment in improving air quality in China.Our analysis revealed regional disparities and annual dynamic changes.Specifically,we focused on the Beijing-Tianjin-Hebei areas as a case study,as the investment primarily targeted industrial activities in urban areas with the goal of improving living conditions for urban residents.The results demonstrate significant differences in investment efficiency between regions.Beijing exhibits relatively high investment efficiency,while cities in Hebei Province require improvement.We identified scale inefficiency,which refers to the ratio of air pollutant reduction to financial investment,as the main factor contributing to regional disparities.However,we found that increasing the total investment scale can help mitigate this effect.Furthermore,our study observed positive but fluctuating annual changes in investment efficiency within this city cluster from 2014 to 2018.Investment-combined technical efficiency,which represents the investment strategy,is the main obstacle to improving yearly investment efficiency.Therefore,in addition to promoting investment strategies at the individual city level,it is crucial to enhance coordination and cooperation among cities to improve the investment efficiency of the entire city cluster.Evaluating the efficiency of government investment and understanding its influencing factors can guide future investment measures and directions.This knowledge can also support policymaking for other projects involving substantial investments.

Carbon nitride with encapsulated nickel for semi-hydrogenation of acetylene: pyridinic nitrogen is responsible for hydrogen dissociative adsorption

A new mechanism of catalyst has been demonstrated in this article. With the interaction between carbon nitride(CN) and encapsulated nickel, the CN in the catalyst has been endowed with new active sites for the adsorption and activation of hydrogen while nickel itself is physically isolated from the contact with reactive molecules. For the selective hydrogenation of acetylene in large amount of ethylene, the catalyst shows excellent ethylene selectivity than the nickel catalyst itself, which is almost totally unselective. Meanwhile, the CN itself is inactive for the reaction. The results of characterization demonstrate that pyridinic nitrogen doped in the carbon matrix should be the active sites for hydrogen dissociative adsorption. The theoretical calculations further confirm the results and provide with the detail in the electron transfer between nickel and CN in the catalyst. The current results supply a new concept for design of high performance catalyst.

Theoretical Study on the Dissociation of Ligands in the Rhodium and Iridium Complexes Containing 1,1,1,5,5,5-Hexafl uo roacetylaceto nato

Functionalization of the inert C-H bonds of unsaturated molecules by transition metal complex is an important means to form new C-C bonds. The functionalization is usually initiated by the ligand dissociation of a complex. In this paper we employ both ab initio and density functional methods to explore the influence of central metals, conformation, solvent and protonation on the ligand dissociation of the （hfac-O,O）2M（L）（py） complexes [M=Rh（Ⅲ） or Ir（Ⅲ）, hfac-O,O=k^2-O,O-1,1,1,5,5,5-hexafluoroacetylacetonato, L = CH3, CH3CO2, （CH3CO）2CH, CH30 or OH, py=pyridine]. We demonstrate that ligand pyridine dissociates more easily than the ＂L＂ ligands un-der study in aprotic solvent and gas phase and the dissociation of pyridine is more facile in the trans-conformation than in the cis-isomer. These phenomena are rationalized based on electronic structure and molecular orbital inter-actions. We show that solvation only slightly stabilizes the complexes and does not change the ligand dissociation ordering. In particular, we show that pyridine is no longer the labile ligand in protic media. Instead, the oxy-gen-containing ligands （apart from those like hfac that form a cyclic structure with the central metal） that coordinate to the central metal via oxygen atom become the labile ones. Finally our calculations indicate that hfac is a stable ligand, even in protic media.