Exploring
noble-metal-free electrocatalysts with high efficiency
for both the hydrogen evolution reaction (HER) and the oxygen evolution
reaction (OER) holds promise for advancing the production of H2 fuel through water splitting. Herein, one-pot synthesis was
introduced for MoS2–Ni3S2 heteronanorods
supported by Ni foam (MoS2–Ni3S2 HNRs/NF), in which the Ni3S2 nanorods were
hierarchically integrated with MoS2 nanosheets. The hierarchical
MoS2–Ni3S2 heteronanorods
allow not only the good exposure of highly active heterointerfaces
but also the facilitated charge transport along Ni3S2 nanorods anchored on conducting nickel foam, accomplishing
the promoted kinetics and activity for HER, OER, and overall water
splitting. The optimal MoS2–Ni3S2 HNRs/NF presents low overpotentials (η10) of 98 and 249 mV to reach a current density of 10 mA cm–2 in 1.0 M KOH for HER and OER, respectively. Assembled as an electrolyzer
for overall water splitting, such heteronanorods show a quite low
cell voltage of 1.50 V at 10 mA cm–2 and remarkable
stability for more than 48 h, which are among the best values of current
noble-metal-free electrocatalysts. This work elucidates a rational
design of heterostructures as efficient electrocatalysts, shedding
some light on the development of functional materials in energy chemistry.
Hierarchical MoS2/polyaniline nanowires, integrating MoS2 nanosheets with conductive polyaniline, serve as prominent anode materials for Li‐ion batteries, presenting high capacity and good cyclability. The polyaniline‐hybrid structure and hierarchical features significantly promote the Li‐storage performance as compared with the bare MoS2, indicating new opportunities for developing electrode nanomaterials.
As the key of hydrogen economy, electrocatalytic hydrogen evolution reactions (HERs) depend on the availability of cost-efficient electrocatalysts. Over the past years, there is a rapid rise in noble-metal-free electrocatalysts. Among them, transition metal carbides (TMCs) are highlighted due to their structural and electronic merits, e.g., high conductivity, metallic band states, tunable surface/bulk architectures, etc. Herein, representative efforts and progress made on TMCs are comprehensively reviewed, focusing on the noble-metal-like electronic configuration and the relevant structural/electronic modulation. Briefly, specific nanostructures and carbon-based hybrids are introduced to increase active-site abundance and to promote mass transportation, and heteroatom doping and heterointerface engineering are encouraged to optimize the chemical configurations of active sites toward intrinsically boosted HER kinetics. Finally, a perspective on the future development of TMC electrocatalysts is offered. The overall aim is to shed some light on the exploration of emerging materials in energy chemistry.
Lithium–sulfur (Li–S) batteries have attracted much attention in the field of electrochemical energy storage due to their high energy density and low cost. However, the “shuttle effect” of the sulfur cathode, resulting in poor cyclic performance, is a big barrier for the development of Li–S batteries. Herein, a novel sulfur cathode integrating sulfur, flexible carbon cloth, and metal–organic framework (MOF)‐derived N‐doped carbon nanoarrays with embedded CoP (CC@CoP/C) is designed. These unique flexible nanoarrays with embedded polar CoP nanoparticles not only offer enough voids for volume expansion to maintain the structural stability during the electrochemical process, but also promote the physical encapsulation and chemical entrapment of all sulfur species. Such designed CC@CoP/C cathodes with synergistic confinement (physical adsorption and chemical interactions) for soluble intermediate lithium polysulfides possess high sulfur loadings (as high as 4.17 mg cm–2) and exhibit large specific capacities at different C‐rates. Specially, an outstanding long‐term cycling performance can be reached. For example, an ultralow decay of 0.016% per cycle during the whole 600 cycles at a high current density of 2C is displayed. The current work provides a promising design strategy for high‐energy‐density Li–S batteries.
On account of increasing demand for energy storage devices, sodium‐ion batteries (SIBs) with abundant reserve, low cost, and similar electrochemical properties have the potential to partly replace the commercial lithium‐ion batteries. In this study, a facile metal‐organic framework (MOF)‐derived selenidation strategy to synthesize in situ carbon‐encapsulated selenides as superior anode for SIBs is rationally designed. These selenides with particular micro‐ and nanostructured features deliver ultrastable cycling performance at high charge–discharge rate and demonstrate ultraexcellent rate capability. For example, the uniform peapod‐like Fe7Se8@C nanorods represent a high specific capacity of 218 mAh g−1 after 500 cycles at 3 A g−1 and the porous NiSe@C spheres display a high specific capacity of 160 mAh g−1 after 2000 cycles at 3 A g−1. The current simple MOF‐derived method could be a promising strategy for boosting the development of new functional inorganic materials for energy storage, catalysis, and sensors.
Flexible single crystalline R-MoO 3 nanobelts with widths of 200-500 nm, lengths of 5-10 µm, and thicknesses of ∼50 nm have been prepared by a facile hydrothermal treatment method. When fabricated as the cathode for lithium ion batteries, the as-synthesized R-MoO 3 nanobelts exhibit excellent rate capability, large capacity, and good cycling stability. An initial discharge capacity of 176 mAh/g can be obtained at 5000 mA/g, retaining a capacity of 115 mAh/g after 50 cycles. The superior high-rate capability can be attributed to the increased conductivity of the electrode during cycling and the nanobelts morphology. The excellent performance makes the R-MoO 3 nanobelts a promising cathode material for rechargeable lithium ion batteries in the application of electronic vehicles and hybrid electronic vehicles.
Thyroid nodules are very common all over the world, and China is no exception. Ultrasound plays an important role in determining the risk stratification of thyroid nodules, which is critical for clinical management of thyroid nodules. For the past few years, many versions of TIRADS (Thyroid Imaging Reporting and Data System) have been put forward by several institutions with the aim to identify whether nodules require fine-needle biopsy or ultrasound follow-up. However, no version of TIRADS has been widely adopted worldwide till date. In China, as many as ten versions of TIRADS have been used in different hospitals nationwide, causing a lot of confusion. With the support of the Superficial Organ and Vascular Ultrasound Group of the Society of Ultrasound in Medicine of the Chinese Medical Association, the Chinese-TIRADS that is in line with China's national conditions and medical status was established based on literature review, expert consensus, and multicenter data provided by the Chinese Artificial Intelligence Alliance for Thyroid and Breast Ultrasound.
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