Synergistic Engineering of Defects and Heterostructures Enhance Lithium/Sodium Storage Properties of F-SnO2-x-SnS2-x Nanocrystals Supported on N,S-Graphene

Phase engineering of the electrode materials in terms of designing heterostructures, introducing heteroatom and defects, improves great prospects in accelerating the charge storage kinetics during the repeated Li⁺/Na⁺ insertion/deintercalation. Herein, a new design of Li/Na-ion battery anodes through phase regulating is reported consisting of F-doped SnO₂-SnS₂ heterostructure nanocrystals with oxygen/sulfur vacancies (V_O/V_S) anchored on a 2D sulfur/nitrogen-doped reduced graphene oxide matrix (F-SnO_2-x-SnS_2-x@N/S-RGO). Consequently, the F-SnO_2-x-SnS_2-x@N/S-RGO anode demonstrates superb high reversible capacity and long-term cycling stability. Moreover, it exhibits excellent great rate capability with 589 mAh g⁻¹ for Li⁺ and 296 mAh g⁻¹ at 5 A g⁻¹ for Na⁺. The enhanced Li/Na storage properties of the nanocomposites are not only attributed to the increase in conductivity caused by V_O/V_S and F doping (confirmed by DFT calculations) to accelerate their charge-transfer kinetics but also the increased interaction between F-SnO_2-x-SnS_2-x and Li/Na through heterostructure. Meanwhile, the hierarchical F-SnO_2-x-SnS_2-x@N/S-RGO network structure enables fast infiltration of electrolyte and improves electron/ion transportation in the electrode, and the corrosion resistance of F doping contributes to prolonged cycle stability.     

Manipulation of Magnetic Skyrmion in a 2D van der Waals Heterostructure via Both Electric and Magnetic Fields

As a promising candidate for the much-desired low power consumption spintronic devices, 2D magnetic van der Waals material also provides a versatile platform for the design and control of topological spin textures. In this work on WTe₂/CrCl₃ bilayer van der Waals heterostructures, a complete Néel-type skyrmion–bimeron–ferromagnet phase transition is demonstrated, accompanied by the evolution of the topological number. This cyclic transition, mediated by a perpendicular magnetic field, is largely driven by the competition between the out-of-plane magnetocrystalline anisotropy and magnetic dipole–dipole interaction. In the presence of a driving current, the Néel-type skyrmion gains a higher velocity yet larger skyrmion Hall angle, in comparison to the bimeron. By incorporating a ferroelectric CuInP₂S₆ monolayer as a substrate, writing and erasing of skyrmions may be regulated using a ferroelectric polarization. This work sheds light on a novel approach to the design and control of magnetic skyrmions on 2D van der Waals materials.     

Magnetoelectric coupling effect of polarization regulation in BiFeO_3/LaTiO_3 heterostructures

An effective regulation of the magnetism and interface of ferromagnetic materials is not only of great scientific significance, but also has an urgent need in modern industry. In this work, by using the first-principles calculations, we demonstrate an effective approach to achieve non-volatile electrical control of ferromagnets, which proves this idea in multiferroic heterostructures of ferromagnetic La TiO_3 and ferroelectric Bi FeO_3. The results show that the magnetic properties and two-dimensional electron gas concentrations of La TiO_3 films can be controlled by changing the polarization directions of Bi FeO_3. The destroyed symmetry being introduced by ferroelectric polarization of the system leads to the transfer and reconstruction of the Ti-3 d electrons, which is the fundamental reason for the changing of magnetic properties.This multiferroic heterostructures will pave the way for non-volatile electrical control of ferromagnets and have potential applications.     

Electronic spectra of quasi-regular Fibonacci systems: Analysis of simple 1D models

The electronic spectra of quasi-regular systems grown following the Fibonacci sequence are investigated via simple one-dimensional tight-binding, one-band models. Different models are considered and the influence of the model parameters and the number of atoms entering the different blocks on the electronic spectrum are discussed.     

Exchange bias of patterned systems: Model and numerical simulation

The magnitude of the exchange bias field of patterned systems exhibits a notable increase in relation to the usual bilayer systems, where a continuous ferromagnetic film is deposited on an antiferromagnet insulator. Here we develop a model, and implement a Monte Carlo calculation, to interpret the experimental observations which is consistent with experimental results, on the basis of assuming a small fraction of spins pinned ferromagnetically in the antiferromagnetic interface layer.     

Non-artificial Layered Heterostructure as Inch-size Single Crystal for Shortwave Polarized-Light Array Detector

Layered heterostructures of different 2D building blocks have invigorated the booming of 2D materials toward high-performance optoelectronic devices. However, contrary to the typical artificial multi-component form, the engineering of non-artificial layered heterostructure into single-phase crystals and resultant properties are largely overlooked. Here, for the first time, an inch-sized single crystal of a non-artificial layered heterostructure is exploited, (PbBr₂)₂(AMTP)₂PbBr₄ ( 1 , AMTP is 4-ammoniomethyltetrahydropyran), serving as polarization-sensitive candidate. Notably, it adopts an interleaved architecture of 2D perovskite slabs with the distinct non-perovskite lattice, thus forming a self-assembled perovskite-intergrowth layered heterostructure. This motif leads to new electronic transitions distributed across two sublattices and affords an inherent in-plane anisotropy ratio of ≈1.6, beyond some known inorganic materials (e.g., GeSe: 1.44; GeAs: 1.49). Combining this in-plane anisotropy and wide bandgap (≈2.9 eV), lateral crystal array of 1 enables shortwave polarized-light detection with ultrahigh responsivity and detectivity under weak illumination compared to some inorganic polarized detectors. As the first demonstration of inch-sized single crystals of non-artificial layered heterostructure, this study affords a new platform to explore candidates toward high-performance optoelectronic devices.     

Progress and Insight of Van der Waals Heterostructures Containing Interlayer Transition for Near Infrared Photodetectors

Van der Waals (vdWs) heterostructures enable bandgap engineering of different 2D materials to realize the interlayer transition via type-II band alignment leading to broaden spectrum that is beyond the cut-off wavelength of individual 2D materials. Interlayer transition has a significant effect on the optoelectronic performance of vdWs heterostructure devices, and strong interlayer transition in 2D vdWs heterojunction is always demandable for sufficient charge transfer and rapid speed response. Herein, a state-of-the-art review is presented on recent progress on interlayer transition in vdWs heterostructures for near-infrared (NIR) photodetectors. First, the general synthesis techniques for vdWs heterostructures, band alignments in the vdWs heterostructures are provided. Then, the mechanism of interlayer transition in vdWs heterostructure and recent progress on interlayer transition in vdWs heterostructures for NIR photodetectors are summarized. Afterward, some worthy applications of NIR photodetectors are reviewed in related areas of this topic. At the last, an outlook, challenges, and future research directions of vdWs heterostructures for photodetectors at broaden response spectrum are presented.     

Efficient Synergism of Chemisorption and Wackenroder Reaction via Heterostructured La2O3-Ti3C2Tx -Embedded Carbon Nanofiber for High-Energy Lithium-Sulfur Pouch Cells

Lithium-sulfur (Li-S) batteries have been regarded as promising next-generation energy storage systems due to their high energy density and low cost, but their practical application is hindered by inferior long-cycle stability caused by the severe shuttle effect of lithium polysulfides (LiPSs) and sluggish reaction kinetics. This study reports a La₂O₃-MXene heterostructure embedded in carbon nanofiber (CNF) (denoted as La₂O₃-MXene@CNF) as a sulfur (S) host to address the above issues. The unique features of this heterostructure endow the sulfur host with synergistic catalysis during the charging and discharging processes. The strong adsorption ability provided by the La₂O₃ domain can capture sufficient LiPSs for the subsequent catalytic conversion, and the insoluble thiosulfate intermediate produced by hydroxyl terminal groups on the surface of MXene greatly promotes the rapid conversion of LiPSs to Li₂S via a “Wackenroder reaction.” Therefore, the S cathode with La₂O₃-MXene@CNF (La₂O₃-MXene@CNF/S) exhibits excellent cycling stability with a low capacity fading rate of 0.031% over 1000 cycles and a high capacity of 857.9 mAh g⁻¹ under extremely high sulfur loadings. Furthermore, a 5 Ah-level pouch cell is successfully assembled for stable cycling, which delivers a high specific energy of 341.6 Wh kg⁻¹ with a low electrolyte/sulfur ratio (E/S ratio).     

Plasma-Assisted Formation of Oxygen Defective NiCoO/NiCoN Heterostructure with Improved ORR/OER Activities for Highly Durable All-Solid-State Zinc-Air Batteries

A plasma approach is reported to synthesize carbon cloth supported carbon fiber and oxygen defect-rich NiCoO/NiCoN hetero-nanowire co-integrated hybrid catalyst (P-NCO/NCN-CF@CC), which includes the advanced features of carbon integration, cation doping, defect/vacancy introduction, and heterostructuring. The P-NCO/NCN shows a fascinating structure with the periphery composed of NCO and the interior co-composed of NCO and NCN. Its formation mainly depends on the high reactivity of energetic species of NH, H_a, and H_b formed during the plasma discharge. The P-NCO/NCN-CF@CC exhibits the oxygen reduction reaction (ORR) activity comparable to the Pt/C and the oxygen evolution reaction (OER) activity higher than RuO₂. When used in the all-solid-state zinc-air batteries, it gives a high maximum power density of 109.8 mW cm⁻² with no performance drop observed for >300 cycles. The DFT calculations indicate that the NCO/NCN heterostructuring and oxygen defects in NCO play the important roles in the high ORR/OER activities of the catalyst. They can modulate the electronic structure of the catalyst, lowering the energy barriers of rate determining steps.     

Dense Platinum/Nickel Oxide Heterointerfaces with Abundant Oxygen Vacancies Enable Ampere-Level Current Density Ultrastable Hydrogen Evolution in Alkaline

Platinum (Pt) remains the benchmark electrocatalyst for alkaline hydrogen evolution reaction (HER), but its industry-scale hydrogen production is severely hampered by the lack of well-designed durable Pt-based materials that can operate at ampere-level current densities. Herein, based on the original oxide layer and parallel convex structure on the surface of nickel foam (NF), a 3D quasi-parallel architecture consisting of dense Pt nanoparticles (NPs) immobilized oxygen vacancy-rich NiO_x heterojunctions (Pt/NiO_x-O_V) as an alkaline HER catalyst is developed. A combined experimental and theoretical studies manifest that anchoring Pt NPs on NiO_x-O_V leads to electron-rich Pt species with altered density of states (DOS) distribution, which can efficiently optimize the d-band center and the adsorption of reaction intermediates as well as enhance the water dissociation ability. The as-prepared catalyst exhibits extraordinary HER performance with a low overpotential of 19.4 mV at 10 mA cm⁻², a mass activity 16.3-fold higher than that of 20% Pt/C, and a long durability of more than 100 h at 1000 mA cm⁻². Furthermore, the assembled alkaline electrolyzer combined with NiFe-layered double hydroxide requires extremely low voltage of 1.776 V to attain 1000 mA cm⁻², and can operate stably for more than 400 h, which is rarely achieved.