Non-covalent functionalization of graphene sheets by pyrene-endcapped tetraphenylethene: Enhanced aggregation-induced emission effect and application in explosive detection.

In this work, a dispersible graphene-based material with a characteristic of aggregation-induced emission (AIE) was prepared by wet chemical reduction of graphene oxide (GO). During the GO reduction process, a conjugated molecule TPEP containing tetraphenylethylene (TPE) and pyrene was employed as a stabilizer because of the π-π interactions and the wrapping effect. The as-prepared rGO-TPEP not only has good dispersion in solution but also processes the AIE feature. Its fluorescence intensity is 2.23 times higher than that of TPEP at the same condition. The unique optical properties and AIE effect enable the rGO-TPEP as a chemical sensor for highly sensitive explosive detection in aggregated state and solid state. In the aggregated state, trace 2,4-dinitrotoluene (DNT) can be detected by the rGO-TPEP even when the concentration is as low as 0.91 ppm, and the quenching constant is as high as 2.47 × 104 M-1.

Rock-Salt MnS0.5Se0.5 Nanocubes Assembled on N-Doped Graphene Forming van der Waals Heterostructured Hybrids as High-Performance Anode for Lithium- and Sodium-Ion Batteries.

Manganese-based chalcogenides would be of latent capacity in serving as anodes for assembling lithium- and/or sodium-ion batteries (LIBs/SIBs) due to their large theoretical capacity, low price, and low-toxicity functionality, while the low electroconductivity and easy agglomeration behavior may impede their technical applications. Here, a solid-state solution of MnS0.5Se0.5 nanocubes in rock-salt phase has been synthesized for the first time at a relatively low temperature from the precursors of Mn(II) acetylacetonate with dibenzyl dichalcogens in oleylamine with octadecene, and the MnS0.5Se0.5 nanocubes have been assembled with N-doped graphene to form a new kind of heterostructured nanohybrids (shortened as MnS0.5Se0.5/N-G hybrids), which are very potential for the fabrication of metal-ion batteries including LIBs and/or SIBs. Investigations revealed that there have been dense vacancies generated and active sites increased via nonequilibrium alloying of MnS and MnSe into the solid-solution MnS0.5Se0.5 nanocubes with segregation and defects achieved in the low-temperature solution synthetic route. Meanwhile, the introduction of N-doped graphene forming heterojunction interfaces between MnS0.5Se0.5 and N-doped graphene would efficiently enhance their electroconductivity and avoid agglomeration of the active MnS0.5Se0.5 nanocubes with considerably improved electrochemical properties. As a result, the MnS0.5Se0.5/N-G hybrids delivered superior Li/Na storage capacities with outstanding rate performance as well as satisfactorily lasting stability (1039/457 mA h g-1 at 0.1 A g-1 for LIBs/SIBs). Additionally, full-cell LIBs of the anodic MnS0.5Se0.5/N-G constructed with cathodic LiFePO4 (LFP) further confirmed the promising future for their practical application.

Azimuthal shear-wave anisotropy measurement in a borehole: Physical modeling and dipole acoustic verification.

An anisotropic physical model is constructed to evaluate the anisotropy measurement. The model consists of a series of equally spaced thin limestone slab sheets cemented with concrete, resulting in a transversely isotropic medium. For the anisotropy measurement evaluation, the borehole model is tested by a standard multipole acoustic tool. The measurement finds an S-wave anisotropy magnitude about 20% and determines the fast S-wave polarization along the alignment direction of the slab sheets. The results of the work not only validate the borehole measurement technology, but also provide a testing facility for calibrating the measurement acoustic tool.

A hybrid method to simulate elastic wave scattering of three-dimensional objects.

A hybrid method based on the finite-difference method and equivalence principle to simulate elastic wave scattering of three-dimensional objects is proposed. In this method, the near fields are first calculated in a rectangular volume containing the object by the finite-difference method. Then the displacements and tractions on a virtual surface are transformed to the far field by the application of the equivalence principle in elastodynamics. The feasibility is verified by comparing modeling results with the analytical solution for the canonical point force source radiation problem. Modeling for complex scatterer structures shows the advantage of this method in handling multi-scale scattering problems.

In Situ Construction of Small Pt NPs Embedded in 3D Spherical Porous Carbon as an Electrocatalyst for Liquid Fuel Oxidation with High Performance.

The realization of small platinum (Pt) nanoparticles (NPs) embedded in conductive porous carbon would largely improve the catalytic activity effectively with more durability, although there remain challenges to achieve such hybrid nanostructures via a simple synthetic route. Here, an efficient and facile profile was demonstrated for the synthesis of one kind of uniform three-dimensional (3D) spherical Pt/C composite electrocatalyst with small monodispersed Pt NPs embedded in the matrix of 3D spherical porous carbon derived from the corresponding spherically polymeric Pt(II) complex. The monodispersed Pt NPs within the uniform 3D Pt/C composite are ∼4.4 nm and they are dispersed homogeneously within the matrix of 3D spherical porous carbon. Investigations showed that the 3D Pt/C composite exhibits high catalytic performances as compared to the commercial catalyst of Pt black for oxidation reactions of ethylene glycol, ethanol, and methanol. This strategy developed in the present study would be available for possible fabrication of some other active 3D porous carbon-supported Pt-based catalysts including their bimetallic and multimetallic counterparts.