Engineering graphene for high-performance supercapacitors: Enabling role of colloidal chemistry

The high electrical conductivity and high specific surface area of graphene are traditionally regarded as the most intriguing features for its promise as the electrode material for supercapacitors. In this perspective, we highlight that from the engineering point of view, the unique colloidal chemistry of chemically functionalized graphene is the key property that has made graphene stand out as a promising nanoscale building block for constructing unique nanoporous electrodes for capacitive energy storage, We present several examples to demonstrate bow the non-covalent colloidal forces between graphene sheets can be harnessed to engineer the nanostructure of graphene-based bulk electrodes for supercapacitors based on both the electrical double layer storage and the redox reaction or pseudo-capacitance mechanisms. The colloidal engineering strategy can be extended to enable other nanomaterials to achieve high energy storage performance.

Effects of Annealing Temperature on Microstructure and Sensing Properties to Alcohol for Nano-La_(0.68)Pb_(0.32)FeO_3

La_(0.68)Pb_(0.32)FeO_3 samples annealed at different temperature were prepared using citrate sol-gel method. With increasing of annealing temperature from 200 to 1000 ℃, the samples crystallize to have single-phase perovskite structure. However, the sensitivity increases at first due to the improvement of crystallization of the perovskite phase, and finally drops attributed to the larger grain size. The optimal sensitivities for La_(0.68)Pb_(0.32)FeO_3 samples annealed at 400, 600, 800, and 1000 ℃ are 12.14, 14.77, 51.07, and 34.55, respectively.

Structural Chemistry of Heteroselenometallic Clusters

About forty heterobimetallic clusters with selenotungstate or se-lenomolybdate showing ten structural types of linear, butterfly, cubane-like, defective-cubane, planar and cage etc. are systematically classified and summarized, and severalsuggestions were proposed, which might be useful for further research on structuralchemistry of heteroselenometallic clusters.

One-pot Synthesis,Characterization and Crystal Structure Determination of Novel 1,4,5-Trisubstituted 1,2,3-Triazole with Two Conformational Isomers:1-Benzyl-5-((4-methoxyphenyl)ethynyl)-4-phenyl-1H-1,2,3-triazole

The title compound l-benzyl-5-（（4-methoxyphenyl）ethynyl）-4-phenyl-1H-1,2,3-triazole（C24H19N3O） was designed and synthesized using one-pot strategy and structural characterization was done by single-crystal X-ray diffraction,NMR,IR and MS.This compound was crystallized out from an ethanolic solution in triclinic system,space group P1 with a =9.9038（9）,b = 10.2928（9）,c = 18.8715（19）A°,α = 103.541（6）,β = 90.507（7）,γ = 97.157（7）°,V =1854.2（3） A°3,Z = 4,crystal size（mm） = 0.25 × 0.1 × 0.1 and R（int） = 0.068.Its asymmetric unit contains two independent molecules.The crystal structure of the title compound is stabilized by intramolecular interactions of types C-H…N and C-H…O.Additionally,X-ray analysis reveals obvious C-H…π,π-π stacking interactions between two adjacent aromatic ring planes.

The chemistry,stability and health effects of phenolic compounds in cultivated hawthorn(Crataegus pinnatifida var.major):a review

Cultivated hawthorn(Crataegus pinnatifida var.major),the principal cultivated hawthorn species in China,is rich in phenolic compounds.These phytochemicals are considered essential bioactive ingredients in different organs of cultivated hawthorn,contributing to its health effects.However,there is lack of a comprehensive review that systematically summarizes the chemistry,health effects,and stability of phenolic substances.This review summarizes recent progress in the characterization,classification,and distribution of phenolic compounds in C.pinnatifida var.major,including procyanidins,flavonoids,phenolic acids,lignans,and others.Importantly,the stability of these compounds was found to be influenced by factors such as the hawthorn development process,postharvest storage,postharvest processing,and the gastrointestinal tract environment.Additionally,the health effects of phenolic compounds in cultivated hawthorn and their underlying mechanisms were discussed.This review provides valuable insights into the utilization of hawthorn resources and the development of the hawthorn industry.

Fabrication of UO2-Gd2O3 Fuel Pellets

The burnable poison Gadolinium oxide was incorporated into UO2 in two of the 36 elements of the fuel assembly in the reload fuel of BWR Units I & II of Tarapur Atomic Power Station. This enabled loading of higher quantities of fuel and achieving a more flattened neutron flux distribution over a longer period of time in the nuclear reactor core. The UO2-Gd2O3 pellets are made by powder pressing and sintering. In the early days of this author’s experience of the 1970s, the processing of UO2-Gd2O3 turned out to be more complex than that of UO2 alone. The small proportion of Gd2O3 in the powder mixture (1.5%) is to be uniformly distributed in the UO2 before and after sintering and substitutional solid solution formation must be complete prior to densification. The inadequacy of homogeneity in the powder and pressed pellets leads to severe defects in the sintering process. In this paper, the processing of U2-Gd2O3 has been revisited. The defects in the product such as “free gadolinia”, low sintered density and bloating, caused by improper processing, have been brought out. The structural defect chemistry aspects of UO2-Gd2O3 and diffusion processes relevant to sintering have also been discussed.

Synthetic and structural chemistry of nickel(Ⅱ) complexes containing dithiolato and phosphine ligands Ⅰ. Preparation and crystal structure of Ni_2(PPh_3)_2(edt)_2

A nickel(Ⅱ) complex containing both dithiolato and phosphine ligands, Ni_2(PPh_3)_2(edt)_2 (edt = SCH_2CH_2S^(2-)), has been prepared and characterized by X-ray diffration. The complex crystallizes in the triclinic system, space group P-1, with a = 10.693(3), b = 17.457 (6), c = 10.606 (3)A, α= 102.84(2), β = 96.49 (2), γ = 82.56(3)°; V = 1906.8 A^3; D_c = 1.439g.cm^(-3) for Z=2; the final con- ventional R was 0.052 based on 3338 observed reflections. Nickel atoms are linked by two sulfur atoms from two edt ligands with the Ni--Ni distance of 2.893 A, and each Ni atom is coordinated by one phosphorus atom and three sulfur atoms with a square-planar geometry, where the average: length of Ni--S bond is 2.180 A and Ni--P bond 2.188 A. The UV-Vis and ~1H NMR spectra have also been recorded.

Synthetic and structural chemistry of hexacobalt cluster compounds——Ⅱ. Preparation and structure of Co_6(μ_3-S)_8(Ph_2PCH_2P(O)Ph_2)_6

Co_6(μ_3-S)_8(Ph_2PCH_2P(O)Ph_2)_6, MW=3012.5, space group R, has the hexagonal parameters, a=26.764(10), c=16.979 (10), V=10532.8~3, Z=3. Mo Kα radiation, λ= 0.71069, Dc=1.425 g/cm^3, μ=9.94 cm^(-3), F(000)=4650, R=0.073 and Rw=0.077 for 1965 observed unique reflections with I>3σ(I). The molecular structure consists of a distorted octahed- ral Co_6-core. The Co-Co and Co-S distances fall in the range of 2.805-2.838 and 2.213-2.253, respectively.

The Effect of Particle Shape on the Structure and Rheological Properties of Carbon-based Particle Suspensions

The structure and rheological properties of carbon-based particle suspensions, i.e., carbon black（CB）, multi-wall carbon nanotube（MWNT）, graphene and hollow carbon sphere（HCS） suspended in polydimethylsiloxane（PDMS）, are investigated. In order to study the effect of particle shape on the structure and rheological properties of suspensions, the content of surface oxygen-containing functional groups of carbon-based particles is controlled to be similar. Original spherical-like CB（fractal filler）, rod-like MWNT and sheet-like graphene form large agglomerates in PDMS, while spherical HCS particles disperse relatively well in PDMS. The dispersion state of carbon-based particles affects the critical concentration of forming a rheological percolation network. Under weak shear, negative normal stress differences（ΔN） are observed in CB, MWNT and graphene suspensions, while ΔN is nearly zero for HCS suspensions. It is concluded that the vorticity alignment of CB, MWNT and graphene agglomerates under shear results in the negative ΔN. However, no obvious structural change is observed in HCS suspension under weak shear, and accordingly, the ΔN is almost zero.

First Investigation of Nonlinear Optical Oxychalcogenide with Three-Dimensional Anionic Framework and Special Windmill-Like Functional Motifs

Oxychalcogenides have been drawn much attention to be explored as nonlinear optical(NLO)materials in recent years.To date,all the NLO oxychalcogenides crystallize in low dimensional structures.Herein,a new oxysulfide K_(2)Ba_(0.5)Ga_(9)O_(2)S_(13) was obtained via three-dimensional(3D){[Ga_(9)O_(2)S_(13)]^(3-)}_(∞)polyanionic framework.As the first oxychalcogenide with 3D NLO-acitve polyanionic framework,K_(2)Ba_(0.5)Ga_(9)O_(2)S_(13) has a wide band gap of 3.72 eV,and exhibits a high laser-induced damage threshold(LIDT,17×AgGaS_(2)).It presents moderate phase-matchable NLO response of 0.5×AgGaS_(2) at 2.1μm and 2×KH_(2)PO_(4) at 1.064μm.The theoretical calculation results indicate that the NLO response is mainly contributed from[Ga(2)S4]unit-built[Ga(2)_(3)S_(10)]windmill-like motif.This work may stimulate the exploration of more NLO oxychalcogenides with balanced performances.

Preparation and Reaction of Naked Metal Clusters for Catalysis and Genetic Materials

Metal clusters that contain a small number of atoms usually present unique properties with dramatic dependence on their sizes,geometric structures,and compositions.The studies of naked metal clusters are devoted to develop new catalysts and functional materials of atomic precision,and enable to improve the fundamental theory of structure chemistry and to understand the basic reactions and properties bridging the gap between atoms and bulk materials.In particular,some interesting superatom clusters have received reasonable research interest indicative of materials gene of clusters.Here in this review,we simply summarize the preparation,stability,and reactivity of naked metal clusters with a few examples displayed.Hopefully it serves as a modest spur to stimulate more interest of related investigations in this field.