Jing Zhang

Recent progress of Raman spectroscopy using deep-ultraviolet light and circularly polarized light and first-principles calculation for single and double resonance Raman spectra.

Abstract

Recent progress of Raman spectroscopy on carbon nanotubes and 2D materials is reviewed as a topical review. The Raman tensor with complex values is related to the chiral 1D/2D materials without mirror symmetry for the mirror in the propagating direction of light, such as chiral carbon nanotube and black phosphorus. The phenomenon of complex Raman tensor is observed by the asymmetric polar plot of helicity-dependent Raman spectroscopy using incident circularly-polarized lights. First-principles calculations of resonant Raman spectra directly give the complex Raman tensor that explains helicity-dependent Raman spectra and laser-energy-dependent relative intensities of Raman spectra. In deep-ultraviolet (DUV) Raman spectroscopy with 266 nm laser, since the energy of the photon is large compared with the energy gap, the first-order and double resonant Raman processes occur in general k points in the Brillouin zone. First-principles calculation is necessary to understand the DUV Raman spectra and the origin of double-resonance Raman spectra. Asymmetric line shapes appear for the G band of graphene for 266 nm laser and in-plane Raman mode of WS₂ for 532 nm laser, while these spectra show symmetric line shapes for other laser excitation. The interference effect on the asymmetric line shape is discussed by fitting the spectra to the Breit–Wigner–Fano line shapes.

Photochromic bacterial cellulose is developed by a green strategy of in situ fermentation method for a multi-color switching system, photo-patterning, and daily sunlight UV monitoring. By designing the unique structure, as-prepared PBCs not only exhibit flexibility, integrability, and wearability but also endow rapid (within 1 min) and stable (30 cycles) discoloration and muti-colors selectivity.

Abstract

Sustainable, durable, and diverse photochromic smart textiles based on bacterial cellulose (BC) have emerged as attractive candidates in UV-sensing applications due to the green and easy functionalization of BC. However, existing BC-based photochromic textiles lack photochromic efficiency and combining fastness. In this study, a green strategy for in situ fermentation is developed to achieve the directional distribution of functional particles and remarkable photochromism in photochromic bacterial cellulose (PBC). The unique functional design obtained by regulating the photochromic dye distribution in 3D nanonetworks of PBCs during in situ growth affords a more uniform distribution and high fastness. Benefiting from the uniform distribution of photochromic dyes and adequate utilization of the 3D network structure, more surface area is provided to receive and utilize the photon energy from the UV rays, making the photochromic process more effective. The as-prepared PBCs exhibited rapid (within 1 min) and stable (30 cycles) discoloration and multicolor selectivity. Their simple preparation process and exceptional wearability, e.g., their flexibility, lightweight, and air permeability, make them suitable for various applications, including tunable color switching systems, photopatterning, and daily sunlight UV monitoring. This study provides empirical value for the biofabrication of photochromic textiles and wearable flexible UV sensors.

This work begins by providing an overview of the upconversion luminescence mechanism in UCNPs. Subsequently, it offers a comprehensive summary of the sensors’ types, design principles, and optimized design strategies for UCNPs sensing. More cost-effective and promising point-of-care testing applications implemented based on UCNPs sensing systems are also summarized. Finally, this review addresses the future challenges and prospects for UCNPs-based sensing.

Abstract

Rare earth-doped upconversion nanoparticles (UCNPs) have achieved a wide range of applications in the sensing field due to their unique anti-Stokes luminescence property, minimized background interference, excellent biocompatibility, and stable physicochemical properties. However, UCNPs-based sensing platforms still face several challenges, including inherent limitations from UCNPs such as low quantum yields and narrow absorption cross–sections, as well as constraints related to energy transfer efficiencies in sensing systems. Therefore, the construction of high-performance UCNPs-based sensing platforms is an important cornerstone for conducting relevant research. This work begins by providing a brief overview of the upconversion luminescence mechanism in UCNPs. Subsequently, it offers a comprehensive summary of the sensors’ types, design principles, and optimized design strategies for UCNPs sensing platforms. More cost-effective and promising point-of-care testing applications implemented based on UCNPs sensing systems are also summarized. Finally, this work addresses the future challenges and prospects for UCNPs-based sensing platforms.

Nature, Published online: 28 February 2024; doi:10.1038/s41586-024-07078-9

An integrated lithium niobate photonic processing engine performs integration and differentiation of analogue signals, solves ordinary differential equations, generates ultra-wideband microwave signals and detects edges in images.

A facile roll-to-roll strategy is developed for fabricating ultraflexible thermoelectric films with superior temperature- and strain-sensing performance, and a prototypical robotic hand for intelligent action feedback and temperature alarm is demonstrated. This work not only brings new inspiration for wearable inorganic thermoelectric devices, but also sets the stage for a wide implementation of multifunctional human-machine interaction systems.

Abstract

Skin-like thermoelectric (TE) films with temperature- and strain-sensing functions are highly desirable for human-machine interaction systems and wearable devices. However, current TE films still face challenges in achieving high flexibility and excellent sensing performance simultaneously. Herein, for the first time, a facile roll-to-roll strategy is proposed to fabricate an ultraflexible chalcogenide glass-polytetrafluoroethylene composite film with superior temperature- and strain-sensing performance. The unique reticular network of the composite film endows it with efficient Seebeck effect and flexibility, leading to a high Seebeck coefficient (731 µV/K), rapid temperature response (≈0.7 s), and excellent strain sensitivity (gauge factor = 836). Based on this high-performance composite film, an intelligent robotic hand for action feedback and temperature alarm is fabricated, demonstrating its great potential in human-machine interaction. Such TE film fabrication strategy not only brings new inspiration for wearable inorganic TE devices, but also sets the stage for a wide implementation of multifunctional human-machine interaction systems.

Glucose is employed as a green and safe additive for a sugaring-out strategy, which can effectively regulate free water content and intermolecular interactions among the components, leading to high-performance hydrogels. The hydrogel exhibits improved mechanical properties and environmental resilience, demonstrating its versatility as a multifunctional sensor for soft robotics.

Abstract

The adoption of hydrogels in most applications is hampered by their high free water content, which limits their mechanical performance and environmental resilience. Herein, this issue is simultaneously addressed by modulating the state of water and the intermolecular interactions in polyacrylamide (PAM) hydrogels. Specifically, PAM hydrogels are toughened by sugaring-out using a monosaccharide (glucose, G). Glucose is found to facilitate PAM hydrogen bonding and interchain interactions. Meanwhile, the high hygroscopicity of glucose converts some of the free water to bound state, endowing the hydrogels with remarkable resilience to extreme environmental conditions. The PAM-G hydrogels are demonstrated as multimodal sensors for soft robotics. Moreover, PAM-G alcogels produced by solvent exchanging with ethanol are shown as effective opto-mechanical sensors. Notably, all these properties are obtained by the inclusion of glucose, a green additive showing no negative health and environmental effect.

E-mode FinFET arrays with 10⁸ on/off ratio. Side-by-side CdS nanofins with narrow standing facets and large height-to-width ratios are created from the bottom up using the graphoepitaxial effect of oriented atomic terraces on annealed miscut surfaces. Subsequently, after deposition of electrodes and gate dielectrics on the nanofins, arrayed enhancement-mode FinFETs with ≈10⁻¹⁴-A standby currents and ≈10⁸ on/off ratios are implemented.

Abstract

The innovation of 3D FinFETs using top-down silicon nanofins represents a significant advancement toward scaling down microchip process nodes to the cutting-edge 3-nm level. While bottom-up semiconductor nanofins also hold promise as building blocks for FinFETs, their controlled growth remains challenging. Drawing inspiration from the guided roots along brick gaps, this study shows that the aligned atomic terraces on an annealed miscut LaAlO₃ surface can trigger an exceptional graphoepitaxial effect, encouraging the bottom-up vapor-phase growth of self-aligned nanostructures such as CdS, CdSe, ZnSe, and ZnTe. Subsequently, the resultant CdS nanofins, characterized by narrow widths of ≈20 nm and large height-to-width ratios exceeding 16, can be seamlessly assembled into arrayed FinFETs on the insulating LaAlO₃ substrate, obviating the need for post-growth alignment steps. Unlike most nanostructure-based planar transistors, which often operate in depletion mode characterized by negative thresholds, these FinFETs operate in enhancement mode with positive thresholds (≈5 V), ≈10⁻¹⁴-A standby currents, and ≈10⁸ on/off current ratios. The achieved ratio surpasses the record for planar enhancement-mode CdS transistors by 4 orders of magnitude, primarily due to the enhanced electrostatic control over the nanofins. Overall, the graphoepitaxially side-by-side nanofins show tremendous potential to expand the repertoire of FinFETs based on non-silicon semiconductors.

The first experimental realization of the long-sought-after last member of the Mn₃X kagome antiferromagnet family, Mn₃Ga is reported in the form of single crystals. Contrary to the calculations that predicted vanishing AHE in stoichiometric Mn₃Ga, here, it is surprisingly found that the Mn deficient Mn_2.4Ga single crystal exhibits the largest AHC reported thus far for Mn₃X kagome antiferromagnets.

Abstract

The recent discoveries of surprisingly large anomalous Hall effect (AHE) in antiferromagnets have attracted much attention due to their promising use in spintronics devices. However, such AHE-hosting antiferromagnetic materials are rare in nature. Herein, it is demonstrated that Mn_2.4Ga, a Fermi-level-tuned kagome antiferromagnet, has a large anomalous Hall conductivity of ≈150 Ω⁻¹ cm⁻¹ at room temperature that surpasses the usual high values (i.e., 20–50 Ω⁻¹ cm⁻¹) observed so far in two outstanding kagome antiferromagnets, Mn₃Sn and Mn₃Ge. Although the triangular spin structure of Mn_2.4Ga shows a weak net magnetic moment of ≈0.05 µ_B per formula unit, it guarantees a nonzero Berry curvature in the kagome plane. Moreover, the anomalous Hall conductivity exhibits a sign reversal with the rotation of a small magnetic field that can be ascribed to the field-controlled chirality of the spin triangular structure. This theoretical calculations further suggest that the large AHE in Mn_2.4Ga originates from a significantly enhanced Berry curvature associated with the tuning of the Fermi level close to the Weyl points. These properties, together with the ability to manipulate moment orientations using a moderate external magnetic field, make Mn_2.4Ga extremely exciting for future antiferromagnetic spintronics.

The Zn-TCPP nanosheet-based flexible memristor with ultra-low both operating voltage and power consumption by a simple spin coating process. Combining various characterization techniques and data analysis, the memristor and the cotton fiber piezoresistance sensor can be used to integrate a flexible biomimetic sensing system, which can remember and recognize the gestures.

Abstract

The flexible biomimetic sensory system inspired by biology exhibits learning, memory, and cognitive behavior toward external stimuli, providing a promising direction for the future development of the artificial intelligence industry. In this work, a Zn-TCPP (TCPP: tetrakis (4-carboxyphenyl) porphyrin) based flexible memristor with ultra-low both operating voltage (≈80 mV) and power consumption (0.39 nW) that simulates typical synaptic plasticities, under continuously adjustable ultra-low voltage pulses (50 mV). The synaptic properties are well maintained even when bending 1000 times at a radius of 5 mm. Furthermore, the flexible bionic sensing system integrated with Zn-TCPP based memristor and cotton fibre piezoresistive sensor can remember pressure and deformation current, thus simulate the learning-forgetting-relearning characteristics under mechanical stimuli (power supply = 100 mV). Especially, the system achieves a high recognition rate of 97% for gestures through self-built datasets and neural network calculations and remains at a high level under the influence of 10% Gaussian noise (80%) and 5 mm bending state (91%). Consequently, the ultralow-power flexible biomimetic sensing system shows great potential in the field of integrated artificial intelligence with multiple modules, paving the way for the development of low-power biomimetic robots in the future.

A universal vapor-phase synthesis method is developed to realize the growth of various halide perovskites (e.g., MAPbBr₃, FAPbBr₃, MAPbI₃, FAPbI₃, and Cs₄PbI₆) with lateral size up to 1.5 cm × 1.5 cm and long-term stability over 180 days under air-environment. The resultant perovskite photodetectors exhibit attractive optoelectronic properties such as superior responsivity, ultrafast response time, and outstanding photoelectric image sensing capability.

Abstract

Ultrathin halide perovskites have drawn tremendous attention in nano-/micro-optoelectronic devices due to their fascinating performance and capability for chip integration. Unfortunately, it is highly challenging to obtain large-scale and chronically stable ultrathin halide perovskites for practical application. Herein, the universal low-temperature vapor-phase synthesis of ultrathin perovskite family materials with thickness down to 2D level and lateral size up to 1.5 cm × 1.5 cm is reported by developing a self-limiting chemical vapor deposition strategy. The perovskite products are found to exhibit superior stability over 180 days under an air environment. The resultant photodetectors demonstrate charming optoelectronic properties such as superior responsivity (3.7 × 10³ A W⁻¹), ultrafast response time (<10 µs), and outstanding low-level light image sensing capability. This universal perovskite synthesis strategy offers great potential for practical applications of halide perovskites in future nano-/micro-optoelectronic devices.

Several methods are proposed to combat the ever-growing issue of counterfeit products in today's market. Carbon dots (CDs) are an attractive solution, as an environment-friendly answer, and also contribute to the circular economy. This review aims to highlight CDs’ luminescence tunability and their photo-chemical and photophysical responsive properties to make them relevant for anticounterfeiting and information encryption applications.

Abstract

Counterfeit products and data vulnerability present significant challenges in contemporary society. Hence, various methods and technologies are explored for anticounterfeiting encoding, with luminescent tracers, particularly luminescent carbon dots (CDs), emerging as a notable solution. CDs offer promising contributions to product security, environmental sustainability, and the circular economy. This critical review aims to highlight the luminescence responsiveness of CDs to physical and chemical stimuli, achieved through nanoengineering their chemical structure. The discussion will delve into the various tunable luminescence mechanisms and decay times of CDs, investigating preferential excitations such as up-conversion, delayed fluorescence, fluorescence, room temperature phosphorescence, persistent luminescence, energy and charge transfer, as well as photo-chemical interactions. These insights are crucial for advancing anticounterfeiting solutions. Following this exploration, a systematic review will focus on the research of luminescent CDs' smart encoding applications, encompassing anticounterfeiting, product tracing, quality certification, and information encryption. Finally, the review will address key challenges in implementing CDs-based technology, providing specific insights into strategies aimed at maximizing their stability and efficacy in anticounterfeiting encoding applications.

An amorphous carbon deposition layer (CDL) induced by SEM electron beam is studied as a carbon-based protective layer on Cu. Compared with graphene, CDL can fill the steps on Cu and the wrinkles and cracks can be avoided during the preparation of CDL, making the diffusion of water or oxygen molecules into the interface of CDL/Cu more difficult. Therefore, the interfacial oxidation of CDL/Cu can be effectively suppressed.

Abstract

An amorphous carbon deposition layer (CDL) with nanoscale thickness induced by scanning electron microscope (SEM) electron beam is studied as a carbon-based protective layer on copper (Cu). CDL is prepared by inducing the deposition of pollutants or hydrocarbons in the cavity of SEM through electron beam irradiation (EBI). Wrinkles and cracks will not form and the interfacial spacing of CDL/Cu is smaller than Graphene/Cu (Gr/Cu). The thickness and coverage of the interfacial oxide layer of CDL/Cu are all smaller than that of the Gr/Cu after the same oxidation conditions. Characterization of Raman mapping also demonstrates that CDL shows better oxidation inhibition effects than graphene. The structure of CDL is determined to be C = C and C = O, CH₃- and C-O can be loaded vertically on CDL. Density functional theory (DFT) is employed for demonstrating the smaller interfacial gap of CDL/Cu, less wrinkles and cracks and larger adsorbing energy of water/oxygen compared with Gr/Cu. Molecular dynamic (MD) simulation also indicates that the diffusion of water or oxygen into CDL/Cu is more difficult and the oxidation of Cu covered by CDL is well suppressed. This work provides a new approach for the study of carbon-based antioxidant materials on Cu.

On the surface of trace amount lanthanide element Yb doped Li-rich layered oxide cathode LLO-0.3%Yb, a Yb-rich and oxygen-vacancy rich layer is spontaneously formed. The dual effects of doping and surface engineering greatly mitigate the lattice oxygen loss and structure degradation normally occurred in electrochemical cycling. Significantly improved cycling stability is thus achieved by the LLO-0.3%Yb sample.

Abstract

Li-rich layered oxides (LLOs) are among the most promising cathode materials with high theoretical specific capacity (>250 mAh g⁻¹). However, capacity decay and voltage hysteresis due tostructural degradation during cycling impede the commercial application of LLOs. Surface engineering and element doping are two methods widely applied tomitigate the structural degradation. Here, it is found that trace amount lanthanide element Yb doping can spontaneously form a surficial Yb-rich layer with high density of oxygen vacancy on the LLO-0.3% Yb (Li_1.2Mn_0.54Co_0.13-xYb_xNi_0.13O₂ where x = 0.003) cathodes, which mitigating lattice oxygen loss and the non-preferred layered-to-spinel-to-rock salt tri-phase transition. Meanwhile, there are also some Yb ions doped into the lattice of LLO, which enhance the binding energy with oxygen and stabilize the lattice in grain interior during cycling. The dual effects of Yb doping greatly mitigate the structure degradation during cycling, and facilitate fast diffusion of lithium ions. As a result, the LLO-0.3% Yb sample achieves significantly improved cycling stability, with a capacity retention of 84.69% after 100 cycles at 0.2 C and 84.3% after 200 cycles at 1 C. These finding shighlight the promising rare element doping strategy that can have both surface engineering and doping effects in preparing LLO cathodes with high stability.

Due to the poor electrical conductivity and lacking of dielectric properties in the layered double hydroxides (LDHs), the work offers an effective strategy to improve the microwave absorption ability and anticorrosion performance of hollow derived LDH composites by temperature control and composition design based on a sacrifice template of ZIF-8.

Abstract

Layered double hydroxides (LDHs) with unique layered structure and atomic composition are limited in the field of electromagnetic wave absorption (EMA) due to their poor electrical conductivity and lack of dielectric properties. In this study, the EMA performance and anticorrosion of hollow derived LDH composites are improved by temperature control and composition design using ZIF-8 as a sacrifice template. Diverse regulation modes result in different mechanisms for EMA. In the temperature control process, chemical reactions tune the composition of the products and construct a refined structure to optimize the LDHs conductivity loss. Additionally, the different phase interfaces generated by the control components optimize the impedance matching and enhance the interfacial polarization. The results show that the prepared NCZ (Ni3ZnC0.7/Co3ZnC@C) has a minimum reflection loss (RL_min) of -58.92 dB with a thickness of 2.4 mm and a maximum effective absorption bandwidth (EAB_max) of 7.36 GHz with a thickness of 2.4 mm. Finally, due to its special structure and composition, the sample exhibits excellent anticorrosion properties. This work offers essential knowledge for designing engineering materials derived from metal organic framework (MOF) with cutting-edge components and nanostructures.

A blue delayed fluorescence molecule (2PCz-XT) that can sensitize green, orange, and red phosphorescent emitters efficiently is developed. Hybrid white organic light-emitting diodes with a high external quantum efficiency (26.8%), high color rendering index (83), and high device operational stability are realized by ultra-thin design of delayed fluorescence 2PCz-XT sensitized phosphorescent layers.

Abstract

In consideration of energy economization and light quality, concurrently attaining high external quantum efficiency (η _ext) and high color rendering index (CRI) is of high significance for the commercialization of hybrid white organic light-emitting diodes (WOLEDs) but is challenging. Herein, a blue luminescent molecule (2PCz-XT) consisting of a xanthone acceptor and two 3,6-diphenylcarbazole donors is prepared, which exhibits strong delayed fluorescence, short delayed fluorescence lifetime, and excellent electroluminescence property, and can sensitize green, orange, and red phosphorescent emitters efficiently. By employing 2PCz-XT as sensitizer and phosphorescent emitters as dopants, efficient two-color and three-color WOLED architectures with ultra-thin phosphorescent emitting layers (EMLs) are proposed and constructed. By incorporating a thin interlayer to modulate exciton recombination zone and reduce exciton loss, high-performance three-color hybrid WOLEDs are finally achieved, providing a high η _ext of 26.8% and a high CRI value 83 simultaneously. Further configuration optimization realizes a long device operational lifetime. These WOLEDs with ultra-thin phosphorescent EMLs are among the state-of-the-art hybrid WOLEDs in the literature, demonstrating the success and applicability of the proposed device design for developing robust hybrid WOLEDs with superb efficiency and color quality.

The temperature of a van der Waals heterostructure is steadily lowered, comprising a single layer Mott insulator on a metallic substrate to follow the phase transition from the Mott insulating state to a Kondo lattice, with the consequent delocalization of the highly correlated electrons in the Mott insulator. The properties of 2D materials are tuned by means of van der Waals heterostructures.

Abstract

Kondo lattices are systems with unusual electronic properties that stem from strong electron correlation, typically studied in intermetallic 3D compounds containing lanthanides or actinides. Lowering the dimensionality of the system enhances the role of electron correlations providing a new tuning knob for the search of novel properties in strongly correlated quantum matter. The realization of a 2D Kondo lattice by stacking a single-layer Mott insulator on a metallic surface is reported. The temperature of the system is steadily lowered and by using high-resolution scanning tunneling spectroscopy, the phase transition leading to the Kondo lattice is followed. Above 27 K the interaction between the Mott insulator and the metal is negligible and both keep their original electronic properties intact. Below 27 K the Kondo screening of the localized electrons in the Mott insulator begins and below 11 K the formation of a coherent quantum electronic state extended to the entire sample, i.e., the Kondo lattice, takes place. By means of density functional theory, the electronic properties of the system and its evolution with temperature are explained. The findings contribute to the exploration of unconventional states in 2D correlated materials.

This review delves into the intricacies of the interfaces formed between two-dimensional (2D) materials and metals, exploring a realm rich with fundamental insights and promising applications. Historically, our understanding of 2D materials emanated from studies employing dielectric substrates or suspended samples. However, integrating metals in the exfoliation and growth processes of 2D materials has opened up new avenues, unveiling various shades of interactions ranging from dispersive forces to covalent bonding. The resulting modifications in 2D materials, particularly transition metal dichalcogenides (TMDCs), offer more than a theoretical intrigue. They bear substantial implications for (opto)electronics, altering Schottky barrier heights and contact resistances in devices. We explore metal-mediated methods for TMDC exfoliation, elucidating the mechanisms and their impact on TMDC-metal interactions. Delving deeper, we scrutinize the fundamentals of these interactions, focusing primarily on MoS2 and Au. Despite the recent surge of interest and extensive studies, critical gaps remain in our understanding of these intricate interfaces. We discuss controversies, such as the changes in Raman or photoemission signatures of MoS2 on Au, and propose potential explanations. The interplay between charge redistribution, substrate-induced bond length variations, and interface charge transfer processes are examined. Finally, we address the intriguing prospect of TMDC phase transitions induced by strongly interacting substrates and their implications for contact design.

Effective thermal conductivity across WS₂/graphene bilayer versus interlayer distance is measured experimentally up to distance of 2.69 nm and extended to larger scale through simulation. It is demonstrated that the trade-off between phonon- and air-conduction mechanisms leads to an existence of a minimum conductivity of 1.41 × 10⁻⁵ W m⁻¹ K⁻¹ at 2.11 nm, or two thousandths of the smallest value reported previously.

Abstract

Controlling and understanding the heat flow at a nanometer scale are challenging, but important for fundamental science and applications. Two-dimensional (2D) layered materials provide perhaps the ultimate solution for meeting these challenges. While there have been reports of low thermal conductivities (several mW m⁻¹ K⁻¹) across the 2D heterostructures, phonon-dominant thermal transport remains strong due to the nearly-ideal contact between the layers. Here, this work experimentally explores the heat transport mechanisms by increasing the interlayer distance from perfect contact to a few nanometers and demonstrates that the phonon-dominated thermal conductivity across the WS₂/graphene interface decreases further with the increasing interlayer distance until the air-dominated thermal conductivity increases again. This work finds that the resulting tradeoff of the two heat conduction mechanisms leads to the existence of a minimum thermal conductivity at 2.11 nm of 1.41 × 10⁻⁵ W m⁻¹ K⁻¹, which is two thousandths of the smallest value reported previously. This work provides an effective methodology for engineering thermal insulation structures and understanding heat transport at the ultimate small scales.

A “confined auto-redox” strategy is reported to fix CeO₂-anchored Pt species on the inner wall of a ZSM-5 cage. The formation of such unique encapsulation structure greatly improves the metal–acid interactions, thereby achieving a high yield of cyclopentanone from furfural selective hydrogenation.

Abstract

Understanding the synergism between the metal site and acid site is of great significance in boosting the efficiency of bi-functional catalysts in many heterogeneous reactions, particularly in biomass upgrading. Herein, a “confined auto-redox” strategy is reported to fix CeO₂-anchored Pt atoms on the inner wall of a ZSM-5 cage, achieving the target of finely controlling the placements of the two active sites. Compared with the conventional surface-supported counterpart, the encapsulated Pt/CeO₂@ZSM-5 catalyst possesses remarkably-improved activity and selectivity, which can convert >99% furfural into cyclopentanone with 97.2% selectivity in 6 h at 160 °C. Besides the excellent catalytic performance, the ordered metal–acid distribution also makes such kind of catalyst an ideal research subject for metal–acid interactions. The following mechanization investigation reveals that the enhancement is strongly related to the unique encapsulation structure, which promotes the migration of the reactants over different active sites, thereby contributing to the tandem reaction.

It is discovered that cGAS-STING pathway and radiotherapy efficacy are closely intertwined in esophageal squamous cell carcinoma by using transcriptome data. Therefore, MnSe₂-lipid with uniform sphere morphology and pH-responsive property is designed. The released Mn²⁺ promotes radiosenstivity and Se element reduces side-effects of radiotherapy.

Abstract

Radiotherapy, a widely used therapeutic strategy for esophageal squamous cell carcinoma (ESCC), is always limited by radioresistance of tumor tissues and side-effects on normal tissues. Herein, a signature based on four core genes of cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) pathway, is developed to predict prognosis and assess immune cell infiltration, indicating that the cGAS-STING pathway and radiotherapy efficacy are closely intertwined in ESCC. A novel lipid-modified manganese diselenide nanoparticle (MnSe₂-lipid) with extraordinarily uniform sphere morphology and tumor microenvironment (TME) responsiveness is developed to simultaneously overcome radioresistance and reduce side-effects of radiation. The uniform MnSe₂ encapsulated lipid effectively achieves tumor accumulation. Octadecyl gallate on surface of MnSe₂ forming pH-responsive metal–phenolic covalent realizes rapid degradation in TME. The released Mn²⁺ promotes radiosensitivity by generating reactive oxygen species induced by Fenton-like reaction and activating cGAS-STING pathway. Spontaneously, selenium strengthens immune response by promoting secretion of cytokines and increasing white blood cells, and performs antioxidant activity to reduce side-effects of radiotherapy. Overall, this multifunctional remedy which is responsive to TME is capable of providing radiosensitivity by cGAS-STING pathway-mediated immunostimulation and chemodynamic therapy, and radioprotection of normal tissues, is highlighted here to optimize ESCC treatment.

A GdNiO₃-based interfacial memristor is proposed, which possesses ultra-high stability performance. Combined with the comprehensive microstructure results, this behavior is ascribed to the interface Schottky barrier variation caused by the 1D oxygen vacancy channel conduction according to the transmission electron microscopy results. Highly accurate neural firing pattern recognition up to ≈99.75% accuracy and monitoring of pattern transitions are succeeded in achieving.

Abstract

Perovskite-type rare earth nickelates based memristor have recently attracted extensive attention in the field of novel storage computing due to their special electronic structure and exotic physical properties. However, there is still a shortage of memristors with ultra-high stability performance, which will provide a solid foundation for future neural network computing with high accuracy recognition rates. Here, a GdNiO₃-based interfacial memristor is presented, which possesses ultra-high stable performance, such as electroforming-free, low device-to-device variation, reliable cyclic switching, high on/off ratio (≈10⁴) and stable pulse modulation of conduction. Combined with the comprehensive microstructure results, this behavior is ascribed to the interface Schottky barrier variation caused by the 1D oxygen vacancy channel conduction according to the transmission electron microscopy results. In particular, based on the device's stable pulse modulation plasticity performance, the study also succeeds in achieving highly accurate neural firing pattern recognition up to ≈99.75% accuracy and monitoring of pattern transitions by implementing a reservoir computing system based on the device. This research advances the progress of nickelates in novel storage computing and paves the way for future efficient memristor-based reservoir computing systems to handle more complex temporal tasks.

The use of MXenes is emerging as an attractive route to optimize the performance and reliability of energy devices. MXenes as an interfacial layer, additives to improve the crystallization of perovskites for solar cell applications, and also as an additive in secondary batteries impart favorable merits, this review delves into such applications and provides future directions for MXene-based energy harvesters.

Abstract

Every once in a while, a revolutionary technological development arises, which leads to a significant change in the way to approach research and push development efforts. The appetite for new technology compels society to look for game-changing materials, that can transform the industry and make advances. Sustainable energy production is paramount to addressing the climate crisis, and energy generation and storage play an important role in the development of self-powered microelectronic devices. The 2D materials, MXenes have emerged as promising candidates for energy and other applications owing to their inherent electrical merits, high specific surface area, and tunable properties. Particularly, in the context of additive and interfacial materials for perovskite solar cell fabrication and utilization as additives in secondary batteries, this review delves into the application of MXenes in such devices. The protocols of MXenes and their nanostructures tailoring toward such applications and, the underlying mechanism is uncovered. Further, the existing challenges and direction for future in MXene-based energy harvesters are discussed.

Utilizing lateral structure devices for switchable photovoltaic (SPV) effect studies provides an effective means to examine metal-perovskite contacts and ion migration. Variations in metal work functions and chemical reactivity significantly influence SPV performance, such as short-circuit current and open-circuit voltage, offering valuable insights for designing and understanding mechanisms in perovskite-based optoelectronic devices.

Abstract

Lead halide perovskites have revolutionized the field of optoelectronics (such as photovoltaics and light emitting diodes) demonstrating extraordinary material properties despite being formed at low temperatures. However, ion migration in the bulk or at the interfaces results in stability issues especially in devices where metal electrodes directly interface with the perovskite film. Utilizing the switchable photovoltaic phenomenon (SPV) in halide perovskites as a measure of ion migration and electrochemical reactions within them, Cs_0.05MA_0.15FA_0.70PbI_2.5Br_0.5 triple cation perovskite, widely used in photovoltaics is evaluated. The various factors determining the SPV, including electric field magnitudes, type of metal contacts, Illumination conditions, and temperature is systematically measured. This study reveals the roles of electrode work functions and reactivities on ion migration and local electronic structure modulation. ITO electrodes demonstrated the highest open-circuit voltage (V_oc) about 0.85 V while Ag electrodes developed conductive filaments. However, the V_oc distribution for Ti and Cr electrodes shows a more pronounced linear correlation with the poling electric field strength. Insights from this lateral design are directly relevant to transistor and memristor architectures and offer inputs into the design of perovskite-based photovoltaic/optoelectronic devices.

Enhancing interfacial adhesion in flexible devices is crucial for their stretchability and longevity. This study employs gold-chalcogen bonding and mercapto silane bridges to reduce sliding and wrinkling issues. The improved fabrication workflow addresses soft lithography challenges to enhance the reliability of flexible microelectronics, making them more practical for applications in biomedical, environmental, and consumer electronics.

Abstract

Van der Waals semiconductors (vdWS) offer superior mechanical and electrical properties and are promising for flexible microelectronics when combined with polymer substrates. However, the self-passivated vdWS surfaces and their weak adhesion to polymers tend to cause interfacial sliding and wrinkling, and thus, are still challenging the reliability of vdWS-based flexible devices. Here, an effective covalent vdWS–polymer lamination method with high stretch tolerance and excellent electronic performance is reported. Using molybdenum disulfide (MoS₂)and polydimethylsiloxane (PDMS) as a case study, gold–chalcogen bonding and mercapto silane bridges are leveraged. The resulting composite structures exhibit more uniform and stronger interfacial adhesion. This enhanced coupling also enables the observation of a theoretically predicted tension-induced band structure transition in MoS₂. Moreover, no obvious degradation in the devices’ structural and electrical properties is identified after numerous mechanical cycle tests. This high-quality lamination enhances the reliability of vdWS-based flexible microelectronics, accelerating their practical applications in biomedical research and consumer electronics.

Choreographing the adaptive shapes of functional materials to exhibit designable mechanical interactions with their environment remains an intricate challenge. This article introduces novel 4D materials, empowering diverse multi-dimensional shape modulations combined to form fine-grained adaptive microarchitectures. Such intelligent material are now ready to support ultra-flexible microelectronics, which can impart autonomy to devices culminating in the tangible realization of artificial morphogenesis.

Abstract

Choreographing the adaptive shapes of patterned surfaces to exhibit designable mechanical interactions with their environment remains an intricate challenge. Here, a novel category of strain-engineered dynamic-shape materials, empowering diverse multi-dimensional shape modulations that are combined to form fine-grained adaptive microarchitectures is introduced. Using micro-origami tessellation technology, heterogeneous materials are provided with strategic creases featuring stimuli-responsive micro-hinges that morph precisely upon chemical and electrical cues. Freestanding multifaceted foldable packages, auxetic mesosurfaces, and morphable cages are three of the forms demonstrated herein of these complex 4-dimensional (4D) metamaterials. These systems are integrated in dual proof-of-concept bioelectronic demonstrations: a soft foldable supercapacitor enhancing its power density (≈108 mW cm⁻²), and a bio-adaptive device with a dynamic shape that may enable novel smart-implant technologies. This work demonstrates that intelligent material systems are now ready to support ultra-flexible 4D microelectronics, which can impart autonomy to devices culminating in the tangible realization of microelectronic morphogenesis.

Significant exchange gap fluctuation has been discovered in a five-layer MnBi₂Te₄ thin film using scanning tunneling microscopy. By applying a 1T out-of-plane magnetic field, the gap fluctuation can be reduced. These findings provide valuable insight into the breakdown of the quantum anomalous Hall effect (QAHE), revealing that magnetic disorder in odd-layer MnBi₂Te₄ thin films must be overcome in order to realize QAHE at higher temperatures.

Abstract

Quantum anomalous Hall (QAH) insulators transport charge without resistance along topologically protected chiral 1D edge states. Yet, in magnetic topological insulators to date, topological protection is far from robust, with zero-magnetic field QAH effect only realized at temperatures an order of magnitude below the Néel temperature T _N, though small magnetic fields can stabilize QAH effect. Understanding why topological protection breaks down is therefore essential to realizing QAH effect at higher temperatures. Here a scanning tunneling microscope is used to directly map the size of exchange gap (E _g,ex) and its spatial fluctuation in the QAH insulator 5-layer MnBi₂Te₄. Long-range fluctuations of E _g,ex are observed, with values ranging between 0 (gapless) and 70 meV, appearing to be uncorrelated to individual surface point defects. The breakdown of topological protection is directly imaged, showing that the gapless edge state, the hallmark signature of a QAH insulator, hybridizes with extended gapless regions in the bulk. Finally, it is unambiguously demonstrated that the gapless regions originate from magnetic disorder, by demonstrating that a small magnetic field restores E _g,ex in these regions, explaining the recovery of topological protection in magnetic fields. The results indicate that overcoming magnetic disorder is the key to exploiting the unique properties of QAH insulators.

A multidimensional sensor consisting of a strain-insensitive pressure sub-sensor in the center and two orthogonally stacked pressure-insensitive anisotropic strain sub-sensors at the top and bottom is developed to distinguish and measure of the type, magnitude, and direction of multiple mechanical stimuli by exploiting their respective selective sensitivities to the stimulus component in one of the three orthogonal axes but insensitive to the others.

Abstract

The construction of piezoresistive sensors capable of distinguishing multiple mechanical stimuli is important for sensing higher level applications. However, the mutual interference between sensing signals is a technical bottleneck for sensors to recognize multiple mechanical stimuli. Inspired by the structure of human skin and muscle, a multidimensional sensor is designed by integrating three sub-sensors. Each sub-sensor is only sensitive to stimulus components in one of the three orthogonal axes, whereas it remains insensitive to others because of its anisotropic sensing properties. Specifically, an omnidirectional gradient wrinkled polyurethane film with MXene-embedded ZnO nanowire arrays serves as a strain-insensitive pressure sub-sensor, while two aligned segmental polyimide/polyurethane films through orthogonal stacking act as two pressure-insensitive anisotropic strain sub-sensors. A unique characteristic of multidimensional sensor is its ability to distinguish and measure the type, magnitude, and direction of strain, pressure, and shear. Moreover, multidimensional sensor exhibits maximal gauge factor of 863.7 for strain and highest sensitivity of 187.71 kPa⁻¹ for pressure. Importantly, multidimensional sensor exhibits an unprecedented ability to quantitatively evaluate shear using a library of electrical responses. The adaptive grasping of robotic hands and free-throw training of players have been demonstrated to initiate the development of robotic object manipulation and physical movement guidance.

This work provides a universal approach to fabricating a series of soft magnetic 2:17-type rare-earth cobalt nanoalloys decorated with graphite (RE₂Co₁₇/graphite, RE = Y, Ce, Pr, Nd, and Gd). The well-structured RE₂Co₁₇/graphite nanostructures exhibit good microwave absorption with an applied frequency range of 11.76–18 GHz, which shows their potential applications as new-type Ku-band electromagnetic materials.

Abstract

A general approach is reported to fabricate a series of single-phase 2:17-type rare-earth cobalt (RE₂Co₁₇, RE = Y, Ce, Pr, Nd, and Gd) nanoalloys by precisely controlled calcium thermic reduction of amorphous RE-Co precursors. High-purity hexagonal RE₂Co₁₇ phases are formed without the precipitation of Co and the other RE-Co phases through the accurately manipulated co-reduction of the two ions, which avoids the disadvantages of the impurity or second phases for RE metal alloys. RE₂Co₁₇/graphite nanostructures constructed with flower-like RE₂Co₁₇ nanoalloys superficially decorated with nanosized graphite are further fabricated by introducing graphene oxides into the co-reduction process. Compared with traditional magnetic planar-anisotropy RE₂Co₁₇ alloys, the preserved high saturation magnetization (51.2–102.9 A m² kg⁻¹) and unusually increased coercivity (152–310.5 Oe) are achieved in these graphite-decorated RE₂Co₁₇ nanoalloys. Moreover, these RE₂Co₁₇/graphite nanostructures exhibit good microwave absorption with an applied frequency range of 11.76–18 GHz, which shows their potential applications as new-type Ku-band electromagnetic materials. This work provides a facial way for the large-scale production for varieties of single-phase 2:17-type RE-Co nanoalloys and expands their application fields by constructing novel composite structures.