Van der Waals polarity-engineered 3D integration of 2D complementary logic.

Vertical three-dimensional integration of two-dimensional (2D) semiconductors holds great promise, as it offers the possibility to scale up logic layers in the z axis1-3. Indeed, vertical complementary field-effect transistors (CFETs) built with such mixed-dimensional heterostructures4,5, as well as hetero-2D layers with different carrier types6-8, have been demonstrated recently. However, so far, the lack of a controllable doping scheme (especially p-doped WSe2 (refs. 9-17) and MoS2 (refs. 11,18-28)) in 2D semiconductors, preferably in a stable and non-destructive manner, has greatly impeded the bottom-up scaling of complementary logic circuitries. Here we show that, by bringing transition metal dichalcogenides, such as MoS2, atop a van der Waals (vdW) antiferromagnetic insulator chromium oxychloride (CrOCl), the carrier polarity in MoS2 can be readily reconfigured from n- to p-type via strong vdW interfacial coupling. The consequential band alignment yields transistors with room-temperature hole mobilities up to approximately 425 cm2 V-1 s-1, on/off ratios reaching 106 and air-stable performance for over one year. Based on this approach, vertically constructed complementary logic, including inverters with 6 vdW layers, NANDs with 14 vdW layers and SRAMs with 14 vdW layers, are further demonstrated. Our findings of polarity-engineered p- and n-type 2D semiconductor channels with and without vdW intercalation are robust and universal to various materials and thus may throw light on future three-dimensional vertically integrated circuits based on 2D logic gates.

The Electron Migration Polarization Boosting Electromagnetic Wave Absorption Based on Ce Atoms Modulated yolk@shell FexN@NGC.

The electron migration polarization is considered as a promising approach to optimize electromagnetic waves (EMW) dissipation. However, it is still difficult to realize well-controlled electron migration and elucidate the related EMW loss mechanisms for current researches. Herein, a novel FexN@NGC/Ce system to construct an effective electron migration model based on the electron leaps among the 4f/5d/6s orbitals of Ce ions is explored. In Fe4N@NGC/CeSA+Cs+NPs, Ce single-atoms (SA) mainly represent a +3 valence state, which can feed the electrons to Ce4+ of clusters (Cs) and CeO2 nanoparticles (NPs) through a conductive network under EMW, leading to the electron migration polarization. Such electron migration loss combined with excellent magnetic loss provided by Fe4N core, results in the optimal EMW attenuation performance with a minimum reflection loss exceeds -85.1 dB and a broadened absorption bandwidth up to 7.5 GHz at 1.5 mm. This study clarifies the in-depth relationship between electron migration polarization and EMW dissipation, providing profound insights into developing well-coordinated magnetic-dielectric nanocomposites for EMW absorption engineering.

Self-Propelled Nanomotor for Cancer Precision Combination Therapy.

The emergence of nanomotor provides an innovative concept for tumor treatment strategies. Conventional chemotherapeutic agents for tumors exit various therapeutic constraints due to the unique microenvironment of the tumor itself. Calcium overload, the aberrant accumulation of free calcium ions in the cytoplasm, is a well-recognized contributor to damage and even cell death in numerous cell types. Such undesired destructive processes can be a novel means applicable to cancer ion interference therapy. Herein, the chemotherapeutic drug doxorubicin (DOX) and calcium peroxide as the driving force into nanomotors through a facile and understandable experimental scheme are successfully assembled. The modification of nucleic acid aptamer and NIR-II fluorescent molecules on its surface simultaneously strengthens both the active targeting and imaging capability of tumor loci. Therefore, by a comprehensive assessment of nanomotors both in vitro and in vivo experiments, CaO2/DOX@HPS-IR-1061-AS1411 demonstrates superior killing effects on tumor cells, and the intracellular reactive oxygen species produced by nanomotors is verified by molecular biology experiments to induce apoptosis of tumor cells and further achieve tumor therapeutic effects.

New Types of Magnetic Nanoparticles for Stimuli-Responsive Theranostic Nanoplatforms.

Magnetic nanomaterials have played a crucial role in promoting the application of nanotechnology in the biomedical field. Although conventional magnetic nanomaterials such as iron oxide nanoparticles (NPs) are used as biosensors, drug delivery vehicles, diagnostic and treatment agents for several diseases, the persistent pursuit of high-performance technologies has prompted researchers to continuously develop new types of magnetic nanomaterials such as iron carbide NPs. Considering their potential application in biomedicine, magnetic NPs responsive to exogenous or endogenous stimuli are developed, thereby enhancing their applicability in more complex versatile scenarios. In this review, the synthesis and surface modification of magnetic NPs are focused, particularly iron carbide NPs. Subsequently, exogenous and endogenous stimuli-responsive magnetic NP-based theranostic platforms are introduced, particularly focusing on nanozyme-based technologies and magnetic NP-mediated immunotherapy, which are emerging stimuli-responsive treatments. Finally, the challenges and perspectives of magnetic NPs to accelerate future research in this field are discussed.

Structure and Defect Engineering Synergistically Boost High Solar-to-Chemical Conversion Efficiency of Cerium oxide/Au Hollow Nanomushrooms for Nitrogen Photofixation.

Photocatalytic nitrogen fixation using solar illumination under ambient conditions is a promising strategy for production of the indispensable chemical NH3 . However, due to the catalyst's limitations in solar energy utilization, loss of hot electrons during transfer, and low nitrogen adsorption and activation capacity, the unsatisfactory solar-to-chemical conversion (SCC) efficiencies of most photocatalysts limit their practical applications. Herein, cerium oxide nanosheets with abundant strain-VO defects were anchored on Au hollow nanomushroom through atomically sharp interfaces to construct a novel semiconductor/plasmonic metal hollow nanomushroom-like heterostructure (denoted cerium oxide-AD/Au). Plasmonic Au extended the absorption of light from the visible to the second near-infrared region. The superior interface greatly enhanced the transfer efficiency of hot electrons. Abundant strain-VO defects induced by interfacial compressive strain promoted adsorption and in situ activation of nitrogen, and such synergistic promotion of strain and VO defects was further confirmed by density functional theory calculations. The judicious structural and defect engineering co-promoted the efficient nitrogen photofixation of the cerium oxide-AD/Au heterostructures with a SCC efficiency of 0.1 % under simulated AM 1.5G solar illumination, which is comparable to the average solar-to-biomass conversion efficiency of natural photosynthesis by typical plants, thus exhibiting significant potential as a new candidate for artificial photosynthesis.

Intelligent Size-Switchable Iron Carbide-Based Nanocapsules with Cascade Delivery Capacity for Hyperthermia-Enhanced Deep Tumor Ferroptosis.

The ferroptosis pathway is recognized as an essential strategy for tumor treatment. However, killing tumor cells in deep tumor regions with ferroptosis agents is still challenging because of distinct size requirements for intratumoral accumulation and deep tumor penetration. Herein, intelligent nanocapsules with size-switchable capability that responds to acid/hyperthermia stimulation to achieve deep tumor ferroptosis are developed. These nanocapsules are constructed using poly(lactic-co-glycolic) acid and Pluronic F127 as carrier materials, with Au-Fe2 C Janus nanoparticles serving as photothermal and ferroptosis agents, and sorafenib (SRF) as the ferroptosis enhancer. The PFP@Au-Fe2 C-SRF nanocapsules, designed with an appropriate size, exhibit superior intratumoral accumulation compared to free Au-Fe2 C nanoparticles, as evidenced by photoacoustic and magnetic resonance imaging. These nanocapsules can degrade within the acidic tumor microenvironment when subjected to laser irradiation, releasing free Au-Fe2 C nanoparticles. This enables them to penetrate deep into tumor regions and disrupt intracellular redox balance. Under the guidance of imaging, these PFP@Au-Fe2 C-SRF nanocapsules effectively inhibit tumor growth when exposed to laser irradiation, capitalizing on the synergistic photothermal and ferroptosis effects. This study presents an intelligent formulation based on iron carbide for achieving deep tumor ferroptosis through size-switchable cascade delivery, thereby advancing the comprehension of ferroptosis in the context of tumor theranostics.

Atomically Unraveling Highly Crystalline Self-Intercalated Tantalum Sulfide with Correlated Stacking Registry-Dependent Magnetism.

In self-intercalated two-dimensional (ic-2D) materials, understanding the local chemical environment and the topology of the filling site remains elusive, and the subsequent correlation with the macroscopically manifested physical properties has rarely been investigated. Herein, highly crystalline gram-scale ic-2D Ta1.33S2 crystals were successfully grown by the high-pressure high-temperature method. Employing combined atomic-resolution scanning transmission electron microscopy annular dark field imaging and density functional theory calculations, we systematically unveiled the atomic structures of an atlas of stacking registries in a well-defined √3(a) × âˆš3(a) Ta1.33S2 superlattice. Ferromagnetic order was observed in the AC' stacking registry, and it evolves into an antiferromagnetic state in AA/AB/AB' stacking registries; the AA' stacking registry shows ferrimagnetic ordering. Therefore, we present a novel approach for fabricating large-scale highly crystalline ic-2D crystals and shed light on a powerful means of modulating the magnetic order of ic-2D systems via stacking engineering, i.e., stackingtronics.

Efficient current-induced spin torques and field-free magnetization switching in a room-temperature van der Waals magnet.

The discovery of magnetism in van der Waals (vdW) materials has established unique building blocks for the research of emergent spintronic phenomena. In particular, owing to their intrinsically clean surface without dangling bonds, the vdW magnets hold the potential to construct a superior interface that allows for efficient electrical manipulation of magnetism. Despite several attempts in this direction, it usually requires a cryogenic condition and the assistance of external magnetic fields, which is detrimental to the real application. Here, we fabricate heterostructures based on Fe3GaTe2 flakes that have room-temperature ferromagnetism with excellent perpendicular magnetic anisotropy. The current-driven nonreciprocal modulation of coercive fields reveals a high spin-torque efficiency in the Fe3GaTe2/Pt heterostructures, which further leads to a full magnetization switching by current. Moreover, we demonstrate the field-free magnetization switching resulting from out-of-plane polarized spin currents by asymmetric geometry design. Our work could expedite the development of efficient vdW spintronic logic, memory, and neuromorphic computing devices.

Proof of Aerobically Autoxidized Self-Charge Concept Based on Single Catechol-Enriched Carbon Cathode Material.

HIGHLIGHTS: An air-breathing chemical self-charge concept of oxygen-enriched carbon cathode. The oxygen-enriched carbon material with abundant catechol groups. Rapid air-oxidation chemical self-charge of catechol groups. The self-charging concept has drawn considerable attention due to its excellent ability to achieve environmental energy harvesting, conversion and storage without an external power supply. However, most self-charging designs assembled by multiple energy harvesting, conversion and storage materials increase the energy transfer loss; the environmental energy supply is generally limited by climate and meteorological conditions, hindering the potential application of these self-powered devices to be available at all times. Based on aerobic autoxidation of catechol, which is similar to the electrochemical oxidation of the catechol groups on the carbon materials under an electrical charge, we proposed an air-breathing chemical self-charge concept based on the aerobic autoxidation of catechol groups on oxygen-enriched carbon materials to ortho-quinone groups. Energy harvesting, conversion and storage functions could be integrated on a single carbon material to avoid the energy transfer loss among the different materials. Moreover, the assembled Cu/oxygen-enriched carbon battery confirmed the feasibility of the air-oxidation self-charging/electrical discharging mechanism for potential applications. This air-breathing chemical self-charge concept could facilitate the exploration of high-efficiency sustainable air self-charging devices.

Improving Electrocatalytic Oxygen Evolution through Local Field Distortion in Mg/Fe Dual-site Catalysts.

Transition metal single atom electrocatalysts (SACs) with metal-nitrogen-carbon (M-N-C) configuration show great potential in oxygen evolution reaction (OER), whereby the spin-dependent electrons must be allowed to transfer along reactants (OH- /H2 O, singlet spin state) and products (O2 , triplet spin state). Therefore, it is imperative to modulate the spin configuration in M-N-C to enhance the spin-sensitive OER energetics, which however remains a significant challenge. Herein, we report a local field distortion induced intermediate to low spin transition by introducing a main-group element (Mg) into the Fe-N-C architecture, and decode the underlying origin of the enhanced OER activity. We unveil that, the large ionic radii mismatch between Mg2+ and Fe2+ can cause a FeN4 in-plane square local field deformation, which triggers a favorable spin transition of Fe2+ from intermediate (dxy 2 dxz 2 dyz 1 dz2 1 , 2.96 µB ) to low spin (dxy 2 dxz 2 dyz 2 , 0.95 µB ), and consequently regulate the thermodyna-mics of the elementary step with desired Gibbs free energies. The as-obtained Mg/Fe dual-site catalyst demonstrates a superior OER activity with an overpotential of 224 mV at 10 mA cm-2 and an electrolysis voltage of only 1.542 V at 10 mA cm-2 in the overall water splitting, which outperforms those of the state-of-the-art transition metal SACs.

Electrically programmable magnetic coupling in an Ising network exploiting solid-state ionic gating.

Two-dimensional arrays of magnetically coupled nanomagnets provide a mesoscopic platform for exploring collective phenomena as well as realizing a broad range of spintronic devices. In particular, the magnetic coupling plays a critical role in determining the nature of the cooperative behavior and providing new functionalities in nanomagnet-based devices. Here, we create coupled Ising-like nanomagnets in which the coupling between adjacent nanomagnetic regions can be reversibly converted between parallel and antiparallel through solid-state ionic gating. This is achieved with the voltage-control of the magnetic anisotropy in a nanosized region where the symmetric exchange interaction favors parallel alignment and the antisymmetric exchange interaction, namely the Dzyaloshinskii-Moriya interaction, favors antiparallel alignment of the nanomagnet magnetizations. Applying this concept to a two-dimensional lattice, we demonstrate a voltage-controlled phase transition in artificial spin ices. Furthermore, we achieve an addressable control of the individual couplings and realize an electrically programmable Ising network, which opens up new avenues to design nanomagnet-based logic devices and neuromorphic computers.

Practicable Zn metal batteries enabled by ultrastable ferromagnetic interface.

Rechargeable zinc (Zn) metal batteries (RZMBs) are demonstrated as sustainable and low-cost alternative in the energy storage industry of the future. However, the elusive Zn deposition behavior and water-originated parasitic reactions bring significant challenges to the fabrication and commercialization of Zn anodes, especially under high plating/stripping capacity. In this work, the ferromagnetic interface in conjunction with the magnetic field (MF) to effectively address these fabrication hurdles is proposed. The introduction of ferromagnetic layer with high chemical durability not only maintains the long-term regulating deposition steadily by magnetic field, but also plays a significant role in preventing side reactions, hence reducing gas production. These merits allow Zn-anode to achieve over 350 h steady Zn-deposition with a depth of discharge (DODZn) up to 82% and translates well to ZnFe-MF||V2O5 full cells, supporting stable cycling at high mass loading of 13.1 mg/cm2, which makes RZMBs configurations promising for commercial applications.

A High-Rigidity Organic-Inorganic Metal Halide Hybrid Enabling Reversible and Enhanced Self-Trapped Exciton Emission under High Pressure.

Zero-dimensional organic-inorganic metal halide hybrids provide ideal bulk-crystal platforms for exploring the pressure engineering of electron-phonon coupling (EPC) and self-trapped exciton (STE) emission at the molecular level. However, the low stiffness of inorganic clusters hinders the reversible tuning of these physical properties. Herein, we designed a Sb3+-doped metal halide with a high emission yield (89.4%) and high bulk modulus (35 GPa) that enables reversible and enhanced STE emission (20-fold) under pressure. The high lattice rigidity originates from the corner-shared cage-structured inorganic tetramers and ring-shaped organic ligands. Further, we reveal that the pressure-enhanced emission regime below 4.5 GPa is owing to the lattice hardening and preferably EPC strength reducing, while the pressure-insensitive emission regime within 4.5-8.5 GPa results from the enhanced intercluster Coulombic attraction force that resists intracluster compression. These results provide insights into the structure-property relation and molecular engineering of zero-dimensional metal halides toward wide-band and pressure-sensitive light sources.

Self-Propelled Janus Nanocatalytic Robots Guided by Magnetic Resonance Imaging for Enhanced Tumor Penetration and Therapy.

Biomedical micro/nanorobots as active delivery systems with the features of self-propulsion and controllable navigation have made tremendous progress in disease therapy and diagnosis, detection, and biodetoxification. However, existing micro/nanorobots are still suffering from complex drug loading, physiological drug stability, and uncontrollable drug release. To solve these problems, micro/nanorobots and nanocatalytic medicine as two independent research fields were integrated in this study to achieve self-propulsion-induced deeper tumor penetration and catalytic reaction-initiated tumor therapy in vivo. We presented self-propelled Janus nanocatalytic robots (JNCRs) guided by magnetic resonance imaging (MRI) for in vivo enhanced tumor therapy. These JNCRs exhibited active movement in H2O2 solution, and their migration in the tumor tissue could be tracked by non-invasive MRI in real time. Both increased temperature and reactive oxygen species production were induced by near-infrared light irradiation and iron-mediated Fenton reaction, showing great potential for tumor photothermal and chemodynamic therapy. In comparison with passive nanoparticles, these self-propelled JNCRs enabled deeper tumor penetration and enhanced tumor therapy after intratumoral injection. Importantly, these robots with biocompatible components and byproducts exhibited biosecurity in the mouse model. It is expected that our work could promote the combination of micro/nanorobots and nanocatalytic medicine, resulting in improved tumor therapy and potential clinical transformations.

General Approach for Two-Dimensional Rare-Earth Oxyhalides with High Gate Dielectric Performance.

Two-dimensional (2D) rare-earth oxyhalides (REOXs) with novel properties offer fascinating opportunities for fundamental research and applications. The preparation of 2D REOX nanoflakes and heterostructures is crucial for revealing their intrinsic properties and realizing high-performance devices. However, it is still a great challenge to fabricate 2D REOX using a general approach. Herein, we design a facile strategy to prepare 2D LnOCl (Ln = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy) nanoflakes using the molten salt method assisted by the substrate. A dual-driving mechanism was proposed in which the lateral growth could be guaranteed by the quasi-layered structure of LnOCl and the interaction between the nanoflakes and the substrate. Furthermore, this strategy has also been successfully applied for block-by-block epitaxial growth of diverse lateral heterostructures and superlattice. More significantly, the high performance of MoS2 field-effect transistors with LaOCl nanoflake as the gate dielectric was demonstrated, exhibiting competitive device characteristics of high on/off ratios up to 107 and low subthreshold swings down to 77.1 mV dec-1. This work offers a deep understanding of the growth of 2D REOX and heterostructures, shedding new light on the potential applications in future electronic devices.

Disorder-tuned conductivity in amorphous monolayer carbon.

Correlating atomic configurations-specifically, degree of disorder (DOD)-of an amorphous solid with properties is a long-standing riddle in materials science and condensed matter physics, owing to difficulties in determining precise atomic positions in 3D structures1-5. To this end, 2D systems provide insight to the puzzle by allowing straightforward imaging of all atoms6,7. Direct imaging of amorphous monolayer carbon (AMC) grown by laser-assisted depositions has resolved atomic configurations, supporting the modern crystallite view of vitreous solids over random network theory8. Nevertheless, a causal link between atomic-scale structures and macroscopic properties remains elusive. Here we report facile tuning of DOD and electrical conductivity in AMC films by varying growth temperatures. Specifically, the pyrolysis threshold temperature is the key to growing variable-range-hopping conductive AMC with medium-range order (MRO), whereas increasing the temperature by 25 °C results in AMC losing MRO and becoming electrically insulating, with an increase in sheet resistance of 109 times. Beyond visualizing highly distorted nanocrystallites embedded in a continuous random network, atomic-resolution electron microscopy shows the absence/presence of MRO and temperature-dependent densities of nanocrystallites, two order parameters proposed to fully describe DOD. Numerical calculations establish the conductivity diagram as a function of these two parameters, directly linking microstructures to electrical properties. Our work represents an important step towards understanding the structure-property relationship of amorphous materials at the fundamental level and paves the way to electronic devices using 2D amorphous materials.

A general thermodynamics-triggered competitive growth model to guide the synthesis of two-dimensional nonlayered materials.

Two-dimensional (2D) nonlayered materials have recently provoked a surge of interest due to their abundant species and attractive properties with promising applications in catalysis, nanoelectronics, and spintronics. However, their 2D anisotropic growth still faces considerable challenges and lacks systematic theoretical guidance. Here, we propose a general thermodynamics-triggered competitive growth (TTCG) model providing a multivariate quantitative criterion to predict and guide 2D nonlayered materials growth. Based on this model, we design a universal hydrate-assisted chemical vapor deposition strategy for the controllable synthesis of various 2D nonlayered transition metal oxides. Four unique phases of iron oxides with distinct topological structures have also been selectively grown. More importantly, ultra-thin oxides display high-temperature magnetic ordering and large coercivity. MnxFeyCo3-x-yO4 alloy is also demonstrated to be a promising room-temperature magnetic semiconductor. Our work sheds light on the synthesis of 2D nonlayered materials and promotes their application for room-temperature spintronic devices.

Sulfur-Doped Carbon for Potassium-Ion Battery Anode: Insight into the Doping and Potassium Storage Mechanism of Sulfur.

The sulfur doping strategy has been attracting extensive interest in potassium-ion battery carbon anodes for the dual potential of improving the capacity and kinetics of carbon anodes. Understanding the doping and potassium storage mechanism of sulfur is crucial to guide the structural design and optimization of high-performance sulfur-doped carbon anodes. Herein, presenting a laboratory-synthesized sulfur-doped hard carbon (SHC) with a sulfur content of 6.4 at. % as an example, we clarify the sulfur doping mechanism and reveal the role of sulfur in potassium storage. The high sulfur content of SHC stems from the selective substitution of sulfur for carbon and the residual trace of sulfur molecular fragments after sulfurization. As a result, thanks to the multifaceted roles of doped sulfur in potassium storage, about twice as much capacity, rate capability, and cycling stability is achieved for SHC against S-free hard carbon at the same test conditions. Furthermore, potassium-ion hybrid capacitors assembled based on an SHC anode demonstrate high energy/power density (139 Wh kg-1/7.3 kW kg-1), along with an extraordinary cycling stability.