Multiferroicity driven by single-atom adsorption on the two-dimensional semiconductor ScCl3.

In recent years, two-dimensional (2D) transition metal halides (such as CrI3) have received more and more attention for the practical applications of spintronic devices due to their unique electronic and magnetic properties. However, most 2D transition metal halides are centrosymmetric and are non-polar, which hinders their applications on nonvolatile memories. Here, on the basis of first-principles calculations, we predict that the adsorption of K single-atoms on the ScCl3 monolayer (denoted as K@ScCl3) could break the structural centrosymmetry and induce a reversible large out-of-plane electric polarization. Simultaneously, the adsorption of K single-atoms induces a magnetic moment localized on Sc ions, which forms a ferromagnetic order with an estimated Curie temperature of ∼37 K. These make the K@ScCl3 monolayer a ferromagnetic ferroelectric semiconductor. These findings propose a new route to realize 2D multiferroic materials, which is of great significance for the research and development of spintronics.

Solar-driven CO2-to-ethanol conversion enabled by continuous CO2 transport via a superhydrophobic Cu2O nano fence.

The overall photocatalytic CO2 reduction reaction presents an eco-friendly approach for generating high-value products, specifically ethanol. However, ethanol production still faces efficiency issues (typically formation rates <605 µmol g-1 h-1). One significant challenge arises from the difficulty of continuously transporting CO2 to the catalyst surface, leading to inadequate gas reactant concentration at reactive sites. Here, we develop a mesoporous superhydrophobic Cu2O hollow structure (O-CHS) for efficient gas transport. O-CHS is designed to float on an aqueous solution and act as a nano fence, effectively impeding water infiltration into its inner space and enabling CO2 accumulation within. As CO2 is consumed at reactive sites, O-CHS serves as a gas transport channel and diffuser, continuously and promptly conveying CO2 from the gas phase to the reactive sites. This ensures a stable high CO2 concentration at reactive sites. Consequently, O-CHS achieves the highest recorded ethanol formation rate (996.18 µmol g-1 h-1) to the best of our knowledge. This strategy combines surface engineering with geometric modulation, providing a promising pathway for multi-carbon production.

Enhanced electrocatalytic hydrogen evolution from nitrogen plasma-tailored MoS2 nanostructures.

Two-dimensional (2D) layered transition metal dichalcogenides such as MoS2 have been viewed as the most favorable candidates for replacing noble metals in catalyzing the hydrogen evolution reaction in water splitting owing to their earth abundance, superb chemical stability, and appropriate Gibbs free energy. However, due to its low number of catalytic sites and basal catalytic inertia, the pristine MoS2 displayed intrinsically unsatisfactory HER catalytic activity. Here, the hydrogen evolution catalytic activities of nanostructured MoS2 powder before and after plasma modification with nitrogen doping were experimentally compared, and the influence of treatment parameters on the hydrogen evolution catalytic performance of MoS2 has been studied. The feasibility of regulating hydrogen evolution catalytic activity by nitrogen doping of MoS2 was verified based on density functional theory calculations. Our work demonstrates a more convenient and faster way to develop cheap and efficient MoS2-based catalysts for electrochemical hydrogen evolution reactions. Additionally, theoretical studies reveal that N-doped MoS2 exhibits strong hybridization between Mo-d and N-p states, causing magnetism to evolve, as confirmed by experiments.

Tuberculosis Diagnosis Using Deep Transferred EfficientNet.

Tuberculosis is a very deadly disease, with more than half of all tuberculosis cases dead in countries and regions with relatively poor health care resources. Fortunately, the disease is curable, and early diagnosis and medication can go a long way toward curing TB patients. Unfortunately, traditional methods of TB diagnosis rely on specialist doctors, which is lacking in areas with high TB mortality rates. Diagnostic methods based on artificial intelligence technology are one of the solutions to this problem. We propose a Deep Transferred EfficientNet with SVM (DTE-SVM), which replaces the pre-trained EfficientNet classification layer with an SVM classifier and achieves auspicious performance on a small dataset. After ten runs of 10-fold Cross-Validation, the DTE-SVM has a sensitivity of 93.89±1.96, a specificity of 95.35±1.31, a precision of 95.30±1.24, an accuracy of 94.62±1.00, and an F1-score of 94.62±1.00. In addition, our study conducted ablation studies on the effect of the SVM classifier on model performance and briefly discussed the results.

Magnetic Field Manipulation of Tetrahedral Units in Spinel Oxides for Boosting Water Oxidation.

Magnetic field enhanced electrocatalysis has recently emerged as a promising strategy for the development of a viable and sustainable hydrogen economy via water oxidation. Generally, the effects of magnetic field enhanced electrocatalysis are complex including magnetothermal, magnetohydrodynamic and spin selectivity effects. However, the exploration of magnetic field effect on the structure regulation of electrocatalyst is still unclear whereas is also essential for underpinning the mechanism of magnetic enhancement on the electrocatalytic oxygen evolution reaction (OER) process. Here, it is identified that in a mixed NiFe2 O4 (NFO), a large magnetic field can force the Ni2+ cations to migrate from the octahedral (Oh ) sites to tetrahedral (Td ) sites. As a result, the magnetized NFO electrocatalyst (NFO-M) shows a two-fold higher current density than that of the pristine NFO in alkaline electrolytes. The OER enhancement of NFO is also observed at 1 T (NFO@1T) under an operando magnetic field. Our first-principles calculations further confirm the mechanism of magnetic field driven structure regulation and resultant OER enhancement. These findings provide a strategy of manipulating tetrahedral units of spinel oxides by a magnetic field on boosting OER performance.

Enhancement of Mass and Charge Transfer during Carbon Dioxide Photoreduction by Enhanced Surface Hydrophobicity without a Barrier Layer.

The CO2 reduction reaction (CRR) represents a promising route for the clean utilization of renewable resources. But mass-transfer limitations seriously hinder the forward step. Enhancing the surface hydrophobicity by using polymers has been proved to be one of the most efficient strategies. However, as macromolecular organics, polymers on the surface hinder the transfer of charge carriers from catalysts to reactants. Herein, we describe an in-situ surface fluorination strategy to enhance the surface hydrophobicity of TiO2 without a barrier layer of organics, thus facilitating the mass transfer of CO2 to catalysts and charge transfer. With less obstruction to charge transfer, a higher CO2, and lower H+ surface concentration, the photocatalytic CRR generation rate of methanol (CH3 OH) is greatly enhanced to up to 247.15 µmol g-1 h-1 . Furthermore, we investigated the overall defects; enhancing the surface hydrophobicity of catalysts provides a general and reliable method to improve the competitiveness of CRR.

Toward Room-Temperature Electrical Control of Magnetic Order in Multiferroic van der Waals Materials.

Electrical control of magnetic order in van der Waals (vdW) two-dimensional (2D) systems is appealing for high-efficiency and low-dissipation nanospintronic devices. For realistic applications, a vdW 2D material with ferromagnetic (FM) and ferroelectric (FE) orders coexisting and strongly coupling at room temperature is urgently needed. Here we present a potential candidate for nonvolatile electric-field control of magnetic orders at room temperature. Using first-principles calculations, we predict the coexistence of room-temperature FM and FE orders in a 2D transition metal carbide, where the spatial distribution of magnetic moments strongly couples with the orientation of out-of-plane electric polarization. Furthermore, an electric-field switching between interfacial FM and ferrimagnetic orders is realizable through constructing a multiferroic vdW heterostructure based on this material. These findings make a significant step toward realizing room-temperature multiferroicity and strong magnetoelectric coupling in 2D materials.

Room-Temperature Ferroelectricity in 1T

van der Waals materials possess an innate layer degree of freedom and thus are excellent candidates for exploring emergent two-dimensional ferroelectricity induced by interlayer translation. However, despite being theoretically predicted, experimental realization of this type of ferroelectricity is scarce at the current stage. Here, we demonstrate robust sliding ferroelectricity in semiconducting 1T^{'}-ReS_{2} multilayers via a combined study of theory and experiment. Room-temperature vertical ferroelectricity is observed in two-dimensional 1T^{'}-ReS_{2} with layer number N≥2. The electric polarization stems from the uncompensated charge transfer between layers and can be switched by interlayer sliding. For bilayer 1T^{'}-ReS_{2}, the ferroelectric transition temperature is estimated to be ∼405 K from the second harmonic generation measurements. Our results highlight the importance of interlayer engineering in the realization of atomic-scale ferroelectricity.

Unconventional distortion induced two-dimensional multiferroicity in a CrO3 monolayer.

Two-dimensional (2D) multiferroic materials with the coexistence of electric and spin polarization offer a tantalizing potential for high-density multistate data storage. However, intrinsic 2D multiferroic semiconductors with high thermal stability are still rare to date. Here, we propose a new mechanism of single-phase multiferroicity. Based on first-principles calculations, we predicted that in a CrO3 monolayer, the unconventional distortion of the square antiprismatic crystal field on Cr-d orbitals will induce an in-plane electric polarization, making this material a single-phase multiferroic semiconductor. Importantly, the magnetic Curie temperature is estimated to be ∼220 K, which is quite high as compared to those of the recently reported 2D ferromagnetic and multiferroic semiconductors. Moreover, both ferroelectric and antiferroelectric phases are observed, providing opportunities for electrical control of magnetism and energy storage and conversion applications. These findings provide a comprehensive understanding of the magnetic and electric behavior in 2D multiferroics and will motivate further research on the application of related 2D electromagnetics and spintronics.

Metal-organic frameworks for advanced drug delivery.

Metal-organic frameworks (MOFs), comprised of organic ligands and metal ions/metal clusters via coordinative bonds are highly porous, crystalline materials. Their tunable porosity, chemical composition, size and shape, and easy surface functionalization make this large family more and more popular for drug delivery. There is a growing interest over the last decades in the design of engineered MOFs with controlled sizes for a variety of biomedical applications. This article presents an overall review and perspectives of MOFs-based drug delivery systems (DDSs), starting with the MOFs classification adapted for DDSs based on the types of constituting metals and ligands. Then, the synthesis and characterization of MOFs for DDSs are developed, followed by the drug loading strategies, applications, biopharmaceutics and quality control. Importantly, a variety of representative applications of MOFs are detailed from a point of view of applications in pharmaceutics, diseases therapy and advanced DDSs. In particular, the biopharmaceutics and quality control of MOFs-based DDSs are summarized with critical issues to be addressed. Finally, challenges in MOFs development for DDSs are discussed, such as biostability, biosafety, biopharmaceutics and nomenclature.

Soluble ACE2-mediated cell entry of SARS-CoV-2 via interaction with proteins related to the renin-angiotensin system.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can cause acute respiratory disease and multiorgan failure. Finding human host factors that are essential for SARS-CoV-2 infection could facilitate the formulation of treatment strategies. Using a human kidney cell line-HK-2-that is highly susceptible to SARS-CoV-2, we performed a genome-wide RNAi screen and identified virus dependency factors (VDFs), which play regulatory roles in biological pathways linked to clinical manifestations of SARS-CoV-2 infection. We found a role for a secretory form of SARS-CoV-2 receptor, soluble angiotensin converting enzyme 2 (sACE2), in SARS-CoV-2 infection. Further investigation revealed that SARS-CoV-2 exploits receptor-mediated endocytosis through interaction between its spike with sACE2 or sACE2-vasopressin via AT1 or AVPR1B, respectively. Our identification of VDFs and the regulatory effect of sACE2 on SARS-CoV-2 infection shed insight into pathogenesis and cell entry mechanisms of SARS-CoV-2 as well as potential treatment strategies for COVID-19.

Prediction of room-temperature ferromagnetism in a two-dimensional direct band gap semiconductor.

Two-dimensional (2D) ferromagnetic (FM) semiconductors with a direct electronic band gap have recently drawn much attention due to their promising potential for spintronic and magneto-optical applications. However, the Curie temperature (TC) of recently synthesized 2D FM semiconductors is too low (∼45 K) and a room-temperature 2D direct band gap FM semiconductor has never been reported, which hinders the development for practical magneto-optical applications. Here, we show that through isovalent alloying, one can increase the TC of a 2D FM semiconductor up to room temperature and simultaneously turn it from an indirect to a direct band gap semiconductor. Using the first-principles calculations, we predict that the alloyed CrMoS2Br2 monolayer is a direct band gap semiconductor with a TC of ∼360 K, whereas the pristine CrSBr monolayer is an indirect band gap semiconductor with a TC of ∼180 K. These findings provide a promising pathway to realize 2D direct band gap FM semiconductors with TC above room temperature, which will greatly stimulate theoretical and experimental interest in future spintronic and magneto-optical applications.

Electrical Control of Magnetic Phase Transition in a Type-I Multiferroic Double-Metal Trihalide Monolayer.

Controlling magnetism of two-dimensional multiferroics by an external electric field provides special opportunities for both fundamental research and future development of low-cost electronic nanodevices. Here, we report a general scheme for realizing a magnetic phase transition in 2D type-I multiferroic systems through the reversal of ferroelectric polarization. Based on first-principles calculations, we demonstrate that a single-phase 2D multiferroic, namely, ReWCl_{6} monolayer, exhibits two different low-symmetric (C_{2}) phases with opposite in-plane electric polarization and different magnetic order. As a result, an antiferromagnetic-to-ferromagnetic phase transition can be realized by reversing the in-plane electric polarization through the application of an external electric field. These findings not only enrich the 2D multiferroic family, but also uncover a unique and general mechanism to control magnetism by electric field, thus stimulating experimental interest.

Switchable encapsulation of polysulfides in the transition between sulfur and lithium sulfide.

Encapsulation strategies are widely used for alleviating dissolution and diffusion of polysulfides, but they experience nonrecoverable structural failure arising from the repetitive severe volume change during lithium-sulfur battery cycling. Here we report a methodology to construct an electrochemically recoverable protective layer of polysulfides using an electrolyte additive. The additive nitrogen-doped carbon dots maintain their "dissolved" status in the electrolyte at the full charge state, and some of them function as active sites for lithium sulfide growth at the full discharge state. When polysulfides are present amid the transition between sulfur and lithium sulfide, nitrogen-doped carbon dots become highly reactive with polysulfides to form a solid and recoverable polysulfide-encapsulating layer. This design skilfully avoids structural failure and efficiently suppresses polysulfide shuttling. The sulfur cathode delivers a high reversible capacity of 891 mAh g-1 at 0.5 C with 99.5% coulombic efficiency and cycling stability up to 1000 cycles at 2 C.

Discovery of twin orbital-order phases in ferromagnetic semiconducting VI3 monolayer.

Spontaneous orbital symmetry breaking in crystals gives rise to abundant novel and interesting physical properties, which sometimes are concealed by the absence of geometrical distortions. We show that a recently discovered 3d2 system, namely the layered VI3 ferromagnetic semiconductor, is a strongly correlated and orbital ordering system. Our analysis reveals that in a VI3-like system, there could be two types of orbital splitting, which are stabilized respectively by strong electronic correlation and inter-atomic exchange interactions. Consequently, on the basis of first-principles calculations, two competing low-energy phases of VI3 monolayer (denoted as twin orbital-order phases) are discovered, in which the metal-insulator transition is driven by strong electronic correlation, and the orbital symmetry breaking is robust against geometrical distortions. In addition, similar phenomena are also observed in other VI3-like systems. These findings shed light on the unusual electronic behavior of a strongly correlated 2D system and will be interesting for nanoscale multi-functional spintronic applications.

Mechanical, Electronic, and Magnetic Properties of NiX2 (X = Cl, Br, I) Layers.

Since the recent experimental discovery of the CrI3 and CrGeTe3 monolayers, van der Waals (vdW) layered transition metal compounds have been recognized as promising candidates to realize 2D ferromagnetic (FM) semiconductors. However, until now, only limited compounds have been proposed to be ferromagnetic semiconductors. Here, on the basis of first-principles calculations, we report that the monolayer, Janus monolayer, and bilayer of NiX2 (X = Cl, Br, I) are intrinsic 2D FM semiconductors. Our results show that exfoliation energy of the NiX2 monolayer is smaller than that of graphene, and all studied NiX2 layers show semiconducting band gaps. The predicted Curie temperature values for NiX2 (X = Cl, Br, I) monolayers ranged from 120 to 170 K with Monte Carlo simulations. For the Janus monolayer, we found that the spin interaction shows a very strong magnetoelectric coupling under an external electric field. Furthermore, for the bilayer of NiX2, our results show that the interlayer coupling is quite weak, indicating the possibility of tuning the magnetic coupling through external manipulations.

Ultra-High-Temperature Ferromagnetism in Intrinsic Tetrahedral Semiconductors.

Ferromagnetic semiconductors exhibit novel spin-dependent optical, electrical, and transport properties, which are promising for next-generation highly functional spintronic devices. However, the possibility of practical applications is hindered by their low Curie temperature. Currently, whether semiconducting ferromagnetism can exist at room temperature is still unclear because of the absence of a solid physical mechanism. Here, on the basis of tight-binding model analysis and first-principles calculations, we report that ferromagnetism in a tetrahedral semiconductor originating from superexchange interactions can be strong enough to survive at room temperature because of the weakening of antiferromagnetic direct-exchange interactions. On the basis of the explored mechanism, a zinc-blende binary transition metal compound, chromium carbide, is predicted to be an intrinsic ferromagnetic tetrahedral semiconductor with a Curie temperature that is as high as ∼1900 K. These findings not only expand the understandings of magnetism in semiconductors but also are of great interest for room-temperature spintronic applications.

High-Temperature Ferromagnetism in an Fe3P Monolayer with a Large Magnetic Anisotropy.

For the development of high-performance spintronic nanodevices, one of the most urgent and challenging tasks is the preparation of two-dimensional materials with room-temperature ferromagnetism and a large magnetic anisotropic energy (MAE). Through first-principles swarm-intelligence structural search calculations, we identify an ideal ferromagnetic Fe3P monolayer, in which Fe atoms show a perfect Kagome lattice, leading to strong in-plane Fe-Fe coupling. The predicted Curie temperature of Fe3P reaches ∼420 K, and its MAE is comparable to those of ferromagnetic materials, such as Fe and Fe2Si. Moreover, the Fe3P monolayer remains as an above room-temperature ferromagnet under biaxial strains as large as 10%. Its lattice can be retained at temperatures of ≤1000 K, exhibiting a high thermodynamic stability. All of these desirable properties make the Fe3P monolayer a promising candidate for applications in spintronic nanodevices.

Toward Intrinsic Room-Temperature Ferromagnetism in Two-Dimensional Semiconductors.

Two-dimensional (2D) ferromagnetic semiconductors have been recognized as the cornerstone for next-generation electric devices, but the development is highly limited by the weak ferromagnetic coupling and low Curie temperature ( TC). Here, we reported a general mechanism which can significantly enhance the ferromagnetic coupling in 2D semiconductors without introducing carriers. On the basis of a double-orbital model, we revealed that the superexchange-driven ferromagnetism is closely related to the virtual exchange gap, and lowering this gap by isovalent alloying can significantly enhance the ferromagnetic (FM) coupling. On the basis of the experimentally available two-dimensional CrI3 and CrGeTe3, the FM coupling in two semiconducting alloy compounds CrWI6 and CrWGe2Te6 monolayers are calculated to be enhanced by 3∼5 times without introducing any carriers. Furthermore, a room-temperature ferromagnetic semiconductor is achieved under a small in-plane strain (4%). Thus, our findings not only deepen the understanding of FM semiconductors but also open a new door for realistic spintronics.