Science China Materials最新文献

With the continuous development of the electrification industry, the development of high-specific batteries has attracted much attention. However, the safety of lithium-ion batteries is currently unable to meet the market demand due to poor thermal stability. Solving the thermal issues is crucial to improve battery safety. Ethylene carbonate (EC) not only plays an important interfacial film-forming role, but also poses safety risks in terms of reactivity. In this work, we conducted a series of gradient experiments utilizing different EC amounts and verified the effect of reducing EC on battery performance. A strategy is also proposed to design a new electrolyte. Ethyl methyl carbonate (EMC) is used instead of EC as the main solvent to improve the thermal safety of the battery, while salts and additives are used to dominate the film formation to improve the cycling stability of the battery under high voltages (4.5 V, ∼90% after 200 cycles). This work paves a new avenue for the development of novel electrolyte systems.

Reabsorption is one of the most fundamental optical phenomena, but it has rarely been considered in spectroscopy-based composition analysis for organic semiconductors. Here, we take four state-of-the-art organic solar cell (OSC) materials as examples, and systematically investigate the influence of reabsorption on photoluminescence emission and excitation spectra by both experimental studies and optical simulations. We find that the overlap between absorption and emission spectra of these OSC materials is strong enough for them to be affected by the reabsorption effect, and the effect becomes more obvious between different species in the multi-components systems. Moreover, three features of the reabsorption effect and the reabsorption strength are identified, with which we have successfully analyzed the composition in a range of OSC materials in both solution and solid-state films. Our work not only provides an important understanding of the largely overlooked feature of reabsorption in the widely used spectroscopic techniques but also offers an effective toolbox for the composition analysis of organic semiconductors.

The electronic structure and magnetic properties of single layer Ga₂O₃ in the presence of Ga and O vacancies are studied by first principles method based on density functional theory. The results show that the introduction of Ga vacancy (V_Ga) leads to a non-zero magnetic moment in single-layer two-dimensional (2D) Ga₂O₃ while V_O does not. We find that Ga vacancies in two different symmetric positions can lead to spin polarized ground states. Notably, when the V_Ga ratio is greater than 1/16 (indicating one Ga vacancy per 16 Ga atoms), single-layer 2D Ga₂O₃ exhibits semi-metallic properties and its spin polarization reaches 100% at the Fermi level. Calculations of these two Ga vacancy systems also indicate a potential long-range ferromagnetic order at a high Curie temperature (355.8 K). Finally, a single layer 2D Ga₂O₃ with high GaI vacancy (V_GaI) ratio can be used as the ferromagnetic layer to obtain the magnetic tunnel junction (MTJ) with high spin filtering effect at the Fermi level. Ga vacant Ga₂O₃/MgO/Ga vacant Ga₂O₃ MTJ exhibits excellent spin-filtering effect (with 100% spin polarization) and a giant tunneling magneto resistance (TMR) ratio (up to 1.12 × 10³%). The results of this paper show that the MTJ based on two-dimensional Ga₂O₃ with room temperature ferromagnetism exhibits reliable performance, showing the possibility of potential applications in spintronics.

Efficient hydrogen production through water splitting relies on the development of high-performance catalysts for the hydrogen evolution reaction (HER). In this study, we synthesized the CoNi SAs@NPs-NC catalyst using multi-metal single-crystal ordered macroporous metal-organic frameworks (MOFs) as precursors. This catalyst features a hierarchical porous structure with ordered macropores and micropores, which not only provides a high specific surface area but also promotes efficient mass diffusion. Furthermore, the incorporation of bimetallic components, coupled with synergistic interactions between single atoms (SAs) and nanoparticles (NPs), significantly enhances its catalytic activity. The CoNi SAs@NPs-NC nanocatalysts demonstrated exceptional activity in the HER, recording overpotentials of 90 mV in 1 M KOH and 61 mV in 0.5 M H₂SO₄, both at a current density of 10 mA cm⁻². In addition, density functional theory (DFT) analysis was employed to investigate the synergistic interactions among CoNi NPs, SAs, and nitrogen dopants. Our finding highlights the promising potential of the CoNi SAs@NPs-NC catalyst for efficient hydrogen evolution, making it a valuable candidate for advancing the field of water splitting.

Non-invasive surface electromyography (sEMG) electrodes have vast potential in fields such as healthcare, human-computer interaction, and entertainment, providing diverse information related to electromyographic signals. Non-invasive sEMG electrodes reduce user risks but gather sEMG signals of lower quality compared to invasive ones. Currently, various advanced electrode materials have been developed for detecting physiological electrical signals, but the majority of them are single channel electrodes. Here, we report 64-channel three-dimensional (3D) Ti₃C₂ MXene/CNT composite electrodes fabricated using bonding-driven self-assembly technologies. These electrodes are characterized by low skin-electrode contact impedance and a high signal-to-noise ratio (SNR) for collection of EMG signals. These electrode arrays exhibit remarkable flexibility, conforming seamlessly to the skin’s curvature. Specifically, the skin-electrode contact impedance of 3D Ti₃C₂ MXene/CNT electrodes decreases by 10-fold compared to Ag/AgCl gel electrodes at a frequency of 100 Hz. Furthermore, when collecting sEMG signals from the arm, the prepared Ti₃C₂ MXene/CNT electrodes exhibit lower baseline noise and higher SNR compared to Ag/AgCl gel electrodes. Furthermore, Ti₃C₂ MXene/CNT electrodes can collect sEMG signals of different hand gestures, while maintaining a high SNR (∼25 dB). By combining machine learning, sEMG signals from different gestures can be identified with a recognition rate exceeding 90%. The exceptional performance and scalability of these 3D Ti₃C₂ MXene/CNT electrodes indicate a promising future for shaping electronic skin and wearable device technologies.

Constructing an accurate interatomic potential and overcoming the exponential growth of structural equilibration time are challenges for atomistic investigations of the composition-dependent structure and dynamics during the vitrification process of deeply supercooled multicomponent metallic liquids. In this work, we describe a state-of-the-art strategy to address these challenges simultaneously. In the case of the representative Zr–Cu–Al system, in combination with a general algorithm for effectively and accurately generating the neural network potentials (NNPs) of multicomponent metallic glasses, we propose a highly efficient atom-swapping hybrid Monte Carlo (SHMC) algorithm for accelerating the thermodynamic equilibration of deeply supercooled liquids. Extensive calculations demonstrate that the newly developed NNP faithfully reproduces the phase stabilities and structural characteristics obtained from ab initio calculations and experiments. In the combined NNP-SHMC algorithm, the structure equilibration time at deeply supercooled temperatures is accelerated by at least five orders of magnitude, and the quenched glassy samples exhibit comparable stability to those prepared in the laboratory. Our results pave the way for next-generation studies of the vitrification process and, thereby, the composition-dependent glass-forming ability and physical properties of multicomponent metallic glasses.

The construction of synergistic catalysis of single atom catalysts (SACs) and oxygen vacancies (O_V) on supports is crucial for the enhancement of heterogeneous catalytic efficiency, yet presents considerable challenges. Herein, we have developed an amine-molecule-assisted in-situ anchoring strategy that effectively stabilizes Pt SACs on O_V sites of reduced TiO₂ (TiO_2−x) by controlling the interaction of amine with Pt species and TiO_2−x. Direct evidence indicates that Pt SACs are anchored on the O_V with forming Pt^δ+–O_V–Ti³⁺ sites and strong metal-support interaction, which not only prevents the sintering of Pt SACs under high-temperature reduction treatments, but also enhances the hydrogen spillover process to facilitate the formation of more O_V sites. During the reverse water-gas shift (RWGS) reaction, the enhanced amount of O_V sites can increase CO₂ adsorption, while the Pt SACs can efficiently promote the activation and spillover of hydrogen. Their combined synergistic effects greatly improve its catalytic performance with a high turnover frequency (TOF) of 9289 h⁻¹ at 330°C and notable stability for over 200 h, surpassing those of Pt clusters and nanoparticles on TiO_2−x. This work provides a new avenue for the controllable synthesis of synergistic catalysts with SACs and O_V, significantly advancing catalytic efficiency.

Single oxygen diffusion event, the most favorable rate-limiting process of epitaxial Cu₂O oxide-island layer-by-layer growth kinetics, may lead to oxygen defects due to thermomechanical coupling. However, the formation rules of oxygen defects remain unclear, preventing the realization of controllable oxygen defects on oxide-island surfaces. Here, we utilize the first-principles method to investigate the formation rules of intrinsic oxygen defects in the surface layers of prototypical metal-oxide (Cu₂O) surfaces under thermomechanical coupling effects. We establish the thermodynamic phase diagram for oxygen-defect-modulated Cu₂O surfaces, enabling the prediction of the growth of oxide islands during Cu oxidation, which aligns closely with in-situ environmental transmission electron microscopy (ETEM) experiment observations. By exploring the strain-modulated phase diagrams, we propose a potential strategy for controlling the type and concentration of oxygen defects on oxide-island surfaces. Our findings provide an effective approach to theoretically understanding the oxidation process of metal surfaces, thus enabling the computational design of high-performance corrosion-resistant surfaces.

Smart electronic textiles with electronic functions like displaying can provide transformative opportunities for wearable devices that traditional rigid devices are hard to realize. A general strategy of enabling textiles to display is weaving light-emitting fibers into textiles and designing control circuits. However, it remains challenging for the current electronic textiles to display full-color images and videos. Here, we demonstrate a large-area integrated electronic textile system (with a size of 72 cm × 50 cm) by weaving light-emitting diode (LED) fibers, touch-sensing fibers and polyester fibers, which could display full-color images (with a gamut of 117.6% NTSC) and continuous videos (with a refresh rate of 11.7 Hz) by designing low-voltage supply mode and parallelly transmitting circuits. After integration of touch-sensing fibers, such textile system could achieve various touch display and interactive functions like smart phones or computers, including hand input of text, hand painting, computing and playing games. The stability and durability of textile system withstanding 5000 bending cycles was also demonstrated for wearable applications. The integrated electronic textile system shows similar flexibility and breathability with regular textiles, which is promising to serve as new human-machine interface to change the way in which people interact with electronics.