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Interconnected hierarchical porous carbon was successfully prepared by direct carbonization of industrial waste sodium lignosulfonate without additional templating and activation agents. The as-prepared carbon sample shows a moderate specific surface area of 903 m2 g−1 and high contents of 8.11 at% oxygen and 1.76 at% nitrogen, which could improve the electrolyte-affinitive surface area in an aqueous electrolyte. When used as electrode materials for symmetric supercapacitors in 7 M KOH electrolytes, the as-synthesized carbon sample exhibits a significantly high gravimetric capacitance of 247 F g−1, a volumetric capacitance of 240 F cm−3, and an areal capacitance of 27.4 μF cm−2 at a current density of 0.05 A g−1. Moreover, a superior energy density of 8.4 W h L−1 (at 13.9 W L−1) and a power density of 5573.1 W L−1 (at 3.5 W h L−1), as well as a remarkable cycling stability after 20 000 cycles at two different current densities were achieved for the assembled supercapacitors. [ABSTRACT FROM AUTHOR]

Quasi-one-dimensional (1D)/two-dimensional (2D) ZrTe3 attracts intense interest as a typical charge density wave (CDW)-bearing material. However, the conventional chemical vapor transport (CVT) synthesis of bulk ZrTe3 is limited by high time consumption, even up to weeks, and low morphological controllability, so it is highly desirable to develop feasible methods for fast and controlled ZrTe3 growth, and so far, these have not been demonstrated. In this work, we first demonstrated that ZrTe3 nanoribbons can be grown directly by a modified chemical vapor deposition (CVD) method. The growth time is significantly reduced to less than 90 min, and the size of ZrTe3 nanoribbons can be well tuned by controlling the growth time and growth temperature. Moreover, differing from most of the other transition metal trichalcogenides (TMTCs), we reveal that ZrTe3 nanoribbons exhibit both competing and synergistic magnetic properties originating from their intrinsic diamagnetism and unexpected ferromagnetism, which can be attributed to their structural imperfection and edge-states due to the reduced dimensionality. Such observable ferromagnetism might favor the exploration of their spin-electronic applications. [ABSTRACT FROM AUTHOR]

Recent discoveries of intrinsic ferromagnetism in low-dimensional ultrathin crystals offer a unique platform for investigating the basics of magnetism and fabricating devices that make use of spins. Here, we report the growth of Cr2.70Se0.60Te3.40 crystals by the chemical-vapour-transport technique. These crystals exhibit ferromagnetism with Curie temperature ∼ 245 K and magnetic moment ∼ 7.15 emu g−1. The nanosheets of Cr2.70Se0.60Te3.40 single crystals possess intrinsic ferromagnetism verified by the anomalous Hall effect, showing the great potential of Cr2.70Se0.60Te3.40 crystals for the fabrication of spintronic, data storage and topological devices. [ABSTRACT FROM AUTHOR]

A spin-valve heterojunction plays a vital role in many technologies such as non-volatile magnetic random-access memories (MRAMs) and high-density magnetic recording. In particular, a spin-valve device based on two-dimensional van der Waals (vdW) heterostructures offers an excellent route for low power consumption and miniaturization of spintronic devices. However, the Curie temperature (TC) of 2D vdW ferromagnetic crystals is mostly lower than room temperature, and the spin-valve heterostructures of room-temperature ferromagnetic 2D crystals are rare. It is necessary and very challenging to realize the room-temperature spin-valve heterojunctions of 2D ferromagnetic crystals. We prepare a 2D room-temperature, ferromagnetic crystal based 2D vdW Fe3GaTe2/MoSe2/Fe3GaTe2 ferromagnet/semiconductor 2D van der Waals heterojunction. The magnetoresistance (MR) of this heterojunction device reaches 3.7% at room temperature (T = 300 K) and 37.7% at 2 K. Importantly the spin-valve effect can still operate at bias currents as low as 10 nA at room temperature in the ferromagnet/semiconductor 2D van der Waals heterojunction. We open a realistic path to 2D magnetic tunnel junctions for next generation spintronic applications at room temperature. [ABSTRACT FROM AUTHOR]

The discovery of two-dimensional (2D) van der Waals (vdW) ferromagnets has provided a broad platform for the study of spintronics and many novel physical phenomena. However, vdW ferromagnetic crystals generally have a low Curie temperature and poor air stability and their magnetic properties are difficult to modulate. As a layered Dirac semimetal, NiTe2 has excellent properties such as high electrical conductivity and high air stability. In this work, we report for the first time the introduction of ferromagnetism into NiTe2 single crystals by doping Cr atoms with the Te-flux method. By controlling the Cr content, the Curie temperature can be tuned from 210 K to 248 K and the saturation magnetic moment from 1.54 emu g−1 to 2.27 emu g−1 which is much higher than the defective magnetism caused by doping. The doped nanosheets still have extremely high air stability, in contrast with most vdW 2D ferromagnet crystals. The results provide opportunities for the study of new highly-tunable, air-stable vdW ferromagnets and their potential applications. [ABSTRACT FROM AUTHOR]

Bimetallic metal–organic frameworks (MOFs) possess two different metal ions as nodes in their molecular frameworks. They are prepared by either one-pot syntheses, wherein different metals are mixed with suitable ligands and linkers, or by adopting post-synthetic modifications by soaking a monometallic MOF in a concentrated solution of a different (but compatible) metal ion. These bimetallic MOFs exhibit synergistic effects and enhanced properties compared to their monometallic counterparts, such as improved adsorption selectivity, selective catalysis and structural stability. Certainly, there are still many open challenges, given that bimetallic MOFs suffer from the typical drawbacks of MOFs, including high moisture sensitivity, easy oxidation due to their varying oxidation states, and possible metal leaching in liquids. In the present perspective, progress in the research on the synthesis and properties of bimetallic MOFs has been reviewed systematically, describing the synthetic strategies adopted to prepare targeted bimetallic MOFs and their applications in gas adsorption, catalysis, energy storage and conversion, and luminescence sensing. Additionally, the challenges facing the synthesis of stable and robust bimetallic MOFs have been discussed with a final outlook on their further development prospects. [ABSTRACT FROM AUTHOR]

In this study, a facile pyrolysis process is utilized to convert a mantis shrimp shell into a 3D bicontinuous porous, highly wrinkled, nitrogen-doped, graphene-like ultrathin carbon sheet (3D BWGC). The 3D BWGC achieves a high surface area of 2300 m2 g−1 and a pore volume of up to 1.63 cm3 g−1. The specific capacitance of the 3D BWGC in 0.5 M H2SO4 electrolyte is 370.9 F g−1 at a current density of 1 A g−1 and an operating voltage window of 1.1 V. By introducing Fe2+, the operating voltage window of 3D BWGC symmetric supercapacitors can reach 1.8 V in a neutral electrolyte, and a specific capacitance of 317.2 F g−1 can be obtained at a current density of 0.5 A g−1. Remarkably, the fabricated symmetric supercapacitors using 2 M MgSO4 + 0.05 M FeSO4 electrolyte demonstrated an energy density as high as 17.7 W h kg−1 at a power density of 180 W kg−1. The assembled supercapacitors exhibit good cycling performance, maintaining an initial capacitance of 87.2% over 30 000 cycles. These excellent performances indicate the promising prospects of 3D BWGC in high-performance electrochemical energy storage. [ABSTRACT FROM AUTHOR]

Molybdenum telluride (MoTe2), as a member of the family of transition metal dichalcogenides (TMDs), gains increasing attention due to its interesting properties such as phase transition. However, it is still challenging to directly grow large area, few-layer, two-dimensional 1T′ and 2H phases of MoTe2 simultaneously on one substrate and to construct a 1T′–2H phase heterostructure. In this work, we have developed a novel facile strategy to achieve large area, phase-controlled growth of few-layer, two-dimensional MoTe2 and lateral 1T′–2H MoTe2 heterostructures on one SiO2/Si substrate directly by special substrate position arrangement during chemical vapor deposition and tuning the cooling rate after growth. We found that a slow cooling rate after film growth is essential for the production of a uniform large-area 2H-MoTe2 film, whereas discrete regions of 2H MoTe2 are preferred to grow under the conditions of a fast cooling rate. Furthermore, the substrate location also plays a crucial role in controlling the synthesis of 1T′ and 2H phases. The resulted few-layer MoTe2 shows a carrier mobility comparable with that of the mechanical exfoliated ones. Our findings pave the way for the study of the physical properties and phase related devices of the MoTe2 and MoTe2 based 1T′–2H heterostructures. [ABSTRACT FROM AUTHOR]