Methane emissions at pressure-regulating stations in China: A comparative analysis of various quantitative methods.

As a key component of the distribution system, metering and pressure-regulating (M&R) stations provide an opportunity for effective mitigation of methane emissions. Given that these stations are readily accessible, above-ground facilities, routine methane emission monitoring can identify issues and with repair or upgrades this can lead to reduced methane emissions. This practice has become an important measure for addressing climate change.

The Microstructure and Thermal Conductive Behavior of Three-Dimensional Carbon/Carbon Composites with Ultrahigh Thermal Conductivity.

Carbon-based composite materials, denoted as C/C composites and possessing high thermal conductivity, were synthesized utilizing a three-dimensional (3D) preform methodology. This involved the orthogonal weaving of mesophase pitch-based fibers in an X (Y) direction derived from low-temperature carbonization, and commercial PAN-based carbon fibers in a Z direction. The 3D preforms were saturated with mesophase pitch in their raw state through a hot-pressing process, which was executed under relatively low pressure at a predetermined temperature.

Preparation, Microstructure and Thermal Properties of Aligned Mesophase Pitch-Based Carbon Fiber Interface Materials by an Electrostatic Flocking Method.

The mesophase pitch-based carbon fiber interface material (TIM) with a vertical array was prepared by using mesophase pitch-based short-cut fibers (MPCFs) and 3016 epoxy resin as raw materials and carbon nanotubes (CNTs) as additives through electrostatic flocking and resin pouring molding process. The microstructure and thermal properties of the interface were analyzed by using a scanning electron microscope (SEM), laser thermal conductivity and thermal infrared imaging methods. The results indicate that the plate spacing and fusing voltage have a significant impact on the orientation of the arrays formed by mesophase pitch-based carbon fibers.

Dual interfaces and confinements on FeN@FeO/VN heterojunction toward high-efficient lithium storage.

Ferroferric oxide (FeO) as an anode material of lithium-ion battery has been widely investigated due to its high theoretical capacity, environmental friendliness, natural abundance, and low cost. However, it suffers from severe aggregation and volume expansion during energy storage. Herein, we rationally construct an advanced FeN@FeO/VN heterostructure via a hydrothermal and followed nitridation process, where the wrapping of conductive FeN on the surface of FeO effectively improves the electron conductivity and alleviates the volume expansion, and VN inhibits the agglomeration of FeN@FeO.

Mott-Schottky Effect in Core-Shell W@W C Heterostructure: Boosting Both Electronic/Ionic Kinetics for Lithium Storage.

The dynamics rate of traditional metal carbides (TMCs) is relatively slow, severely limiting its fast-charging capacity for lithium-ion batteries (LIBs). Herein, the core-shell W@W C heterostructure is developed to form Mott-Schottky heterostructure, thereby simultaneously accelerating the electronic and ionic transport kinetics during the charging/discharging process. The W nanoparticles are partially reduced into W C to form a particular core-shell structure with abundant heterogeneous interfaces.

Regulating d-Band Center of Ti C MXene Via Nb Alloying for Stable and High-Efficient Supercapacitive Performances.

Ti C MXene with the lowest formula weight is expected to gain superior advantages in gravimetric capacitances over other heavier MXenes. Nevertheless, its poor chemical and electrochemical stability is the most fatal drawback and seriously hinders its practical applications. Herein, an alloy engineering strategy at the transition metal-sites of Ti C MXene is proposed.

Zero-strain strategy incorporating TaC with TaO to enhance its rate capacity for long-term lithium storage.

TaO holds great potential for lithium storage due to its high theoretical capacity and long-life cycling. However, it still suffers from an unsatisfactory rate capability because of its low conductivity and significant volume expansion during the charging/discharging process. In this study, a zero-strain strategy was developed to composite TaO with zero-strain TaC as an anode for lithium-ion batteries (LIBs).

Two-Dimensional Ordered Double-Transition Metal Carbides for the Electrochemical Nitrogen Reduction Reaction.

The electrochemical nitrogen reduction reaction (NRR) provides a green and sustainable strategy as an alternative to the Haber-Bosch process. The development of electrocatalysts with low overpotential, high selectivity, and fast reaction kinetics remains a significant challenge. Here, density functional theory computations are carried out to systematically predict the prospect of 18 two-dimensional (2D) ordered double-transition metal carbides (MXenes) as NRR electrocatalysts.

Constructing the Bridge from Isotropic to Anisotropic Pitches for Preparing Pitch-Based Carbon Fibers with Tunable Structures and Properties.

Synthetic naphthalene pitches (SNPs) with isotropy and anisotropy were prepared by a simple thermal polycondensation method to fabricate pitch-based carbon fibers. The structural characteristic, thermal stability, phase-separation behavior, and melt-spinnability of the SNPs and the structural properties of the derived carbon fibers were systematically investigated. The results show that spinnable SNPs with controllable mesophase contents ranging from 0 to 100 vol % and softening points (210-290 °C) could be easily obtained by a nitrogen-bubbling treatment to improve their thermal stability and melt-spinnability by avoiding the phase separation of liquid crystal (LC) in the pitch.

Grain boundary engineering of CoO nanomeshes for efficient electrochemical oxygen evolution.

The development of high-efficiency and stable electrocatalysts is significant for energy conversion and storage. The oxygen evolution reaction (OER), a pivotal half reaction, is seriously limited in its practical applications due to its sluggish kinetics and thus an excellent electrocatalyst for OER is urgently required. In this paper, we design a novel CoO nanomesh (CoO NMs) with high density grain boundaries (GBs), which functions as a highly efficient and steady OER electrocatalyst.

Impact of Microstructure on the Electrochemical Performance of Round-Shaped Pitch-Based Graphite Fibers.

In this study, three kinds of round-shaped pitch-based graphite fiber with different microstructural features (crystallinity and carbon layer orientation) were fabricated by melt-spinning, preoxidation, carbonization and graphitization. The morphology, crystalline size and carbon layer orientation of carbon fibers from different pitch precursors and spinning rates were characterized through X-ray diffraction, scanning electron microscopy and transmission electron analyses. The correlation of the electrochemical performance and microstructure of graphite fibers as anode materials for lithium-ion batteries was investigated.

Graphene Armored with a Crystal Carbon Shell for Ultrahigh-Performance Potassium Ion Batteries and Aluminum Batteries.

Graphene is of great significance in energy storage devices. However, a graphene-based electrode is difficult to use in direct applications due to the large surface area and flexibility, which leads to the excessive consumption of electrolyte, low Coulombic efficiency, and electrode shedding behaviors. Herein, a special crystal carbon@graphene microsphere (CCGM) composite was successfully synthesized.

Effect of Liquid Crystalline Texture of Mesophase Pitches on the Structure and Property of Large-Diameter Carbon Fibers.

Two types of carbon fibers with a large diameter of ∼22 μm, derived from unstirred and vigorously stirred mesophase pitch melts with different liquid crystalline mesophase textures, were prepared by melt-spinning, stabilization, carbonization, and graphitization treatments. The morphology, microstructure, and physical properties of the carbon fibers derived from the two kinds of mesophase precursors after various processes were characterized in detail. The results show that the optical texture (i.

Ablation Behavior of the SiC-Coated Three-Dimensional Highly Thermal Conductive Mesophase-Pitch-Based Carbon-Fiber-Reinforced Carbon Matrix Composite under Plasma Flame.

This study is focused on a novel high-thermal-conductive C/C composite used in heat-redistribution thermal protection systems. The 3D mesophase pitch-based carbon fiber (CF) preform was prepared using CF in the X (Y) direction and polyacrylonitrile carbon fiber (CF) in the Z direction. After the preform was densified by chemical vapor infiltration (CVI) and polymer infiltration and pyrolysis (PIP), the 3D high-thermal-conductive C/C (C/C) composite was obtained.

CsCdVOCl and CsCdVOBr: two new non-centrosymmetric oxyhalides containing d and d cations and exhibiting second harmonic generation activity.

Two new oxyhalides including d0 and d10 cations, Cs4Cd2V4O12Cl4 (1) and Cs3CdV4O12Br (2), were successfully synthesized via a solid phase reaction. Their crystal structures have been determined by X-ray single crystal diffraction. Compound 1 crystallizes in space group Cm (no.

A Comparison of Ethylene-Tar-Derived Isotropic Pitches Prepared by Air Blowing and Nitrogen Distillation Methods and Their Carbon Fibers.

Two isotropic pitches were prepared by air blowing and nitrogen distillation methods using ethylene tar (ET) as a raw material. The corresponding carbon fibers were obtained through conventional melt spinning, stabilization, and carbonization. The structures and properties of the resultant pitches and fibers were characterized, and their differences were examined.