Materials Today最新文献

Aqueous zinc batteries (AZBs) are promising for large-scale energy storage. However, severe side reactions and Zn dendrite growth are challenging. “Water-in-salt” and organic/aqueous hybrid electrolytes address these problems but compromise the high ionic conductivity, superior safety, low cost, and good sustainability. Herein, an asymmetric acceptor–donor small organic molecule (NMU) is proposed to boost Zn anodes without compromising the advantages of AZBs. It is found that NMU molecules alter the H-bonding network and reconstruct Zn²⁺ solvation sheath. Besides, NMU additives tend to be absorbed on the Zn surface to build a water-poor electrical double layer and can in-situ form a robust solid-electrolyte interphase layer that protects the Zn anode. The Zn (0 0 2) plane can be predominately guided by NMU. Consequently, the lifespan of the Zn||Zn cell using NMU can maintain over 3000 h and the average Coulombic efficiency of the Zn||Cu cell reaches 99.7 % throughout 1800 cycles. Additionally, our strategy can be applied in highly-stable and versatile full cells with MnO₂, activated carbon and conversion-type I₂ (capacity retention: 92.5 % throughout 10,000 cycles) cathodes under practical electrode ratios. The Zn||I₂ pouch cell with NMU also presents good cycling stability over 1100 cycles.

Two-dimensional (2D) transition metal carbides/nitrides, MXenes (in particular Ti₃C₂T_x), and three-dimensional (3D) structures such as polymeric hydrogels or aerogels, are promising families of materials, each in their own right, with advantageous properties for applications in biomedicine, water treatment, electronic devices, and energy. Combination of MXenes with hydro- or aerogels may further improve their individual properties and impart new characteristics. Potentially, it can also significantly improve the chemical stability of MXenes, which is currently one of the main limiting factors for their widespread use. In this paper, we review some representative fabrication techniques and properties of Ti₃C₂T_x MXene/3D hydrogel and aerogel composites, as well as selected applications of these composites for energy storage and harvesting, biology and medicine, water treatment, and EMI shielding.

Metal-organic frameworks (MOFs)-engineered reactive-oxygen catalytic materials (ROCMs) have offered essential contributions to boosting the biocatalytic efficiency in diverse biomedical applications. While since the varied coordination environments, abundant node-ligand pairs, and multiple or complex atom sites, precisely overviewing the mechanisms and revealing the structure–reactivity relationships of MOFs-engineered ROCMs still confront great challenges, which is essential to direct the future design and applications of ROCMs. Here, we provide a comprehensive summarization of the latest progress and future trends in MOFs-engineered ROCMs with enzyme-mimicking structures for ROS regulation and biotherapeutic applications. First, the catalytic behaviors and fundamental mechanisms of MOFs-engineered ROCMs on regulating ROS levels are outlined. Then, the enzyme-mimicking coordination environments and structure evolutions of MOFs-engineered ROCMs are discussed thoroughly, including coordination modulation, hybrid structures, carbon nanostructures, and single-atom materials. Particularly, we offer unique insights into enzyme structure mimicking, microenvironment modulation, structure evolutions, and theoretical understanding for revealing mechanisms. Thereafter, the representative biotherapeutic applications have been summarized with a unique focus on structural property-reactivity relationships. Finally, we systematically highlight the current challenges and future perspectives. Overall, this is a timely review that focuses on creating MOF structures for reactive-oxygen biocatalysis from structure-activity relationships to biological properties. We envision this cutting review will substantially stimulate the development and widespread utilization of MOFs-engineered ROCMs in biomedical applications.

Defective carbon materials have emerged as promising candidates for the electrocatalysis of oxygen reduction reaction (ORR) to selectively produce H₂O₂. However, distinguishing the roles of oxygenates and carbon defects in carbon for 2e- ORR remains to be challenging. In a recent issue of Nature Communications, Yao and coworkers pinpointed the major active sites in oxygenated carbon materials and identified the key intermediate employing a series of dynamic and simulation techniques. In addition to highlight the proposed work, this comment article also discussed pioneering methodologies to characterize structure dynamics and probe the integral active center for rational design of carbon based catalysts with atomic precision.

Spinal cord injury (SCI) is a devastating neurotrauma, affecting 250,000 to 500,000 people annually, and typically results in paralysis. Electrostimulation can promote neuronal growth, but the formation of a lesion cavity post-SCI inhibits regrowth, limiting its efficacy. Bridging the lesion with a structured, electroactive substrate to direct electrostimulation to growing neurites could support and drive neuronal regrowth through the lesion to enable functional recovery but to date, no such platform exists. This study describes the development of an electroconductive (15 ± 5 S/m), 3D-printed scaffold, comprising a polypyrrole/polycaprolactone framework filled with biomimetic & neurotrophic extracellular matrix. 3D printing allowed inclusion of channels in the scaffold designed to mimic the size of human corticospinal tracts to direct electrostimulation to growing neurons. Scaffolds exhibited excellent biocompatibility with both neurons and human primary astrocytes and maintained electrical and biofunctionality when scaled to match the size of human corticospinal tracts. When neurons were cultured for 7 days on the scaffolds under continuous electrostimulation (200 mV/mm, 12 Hz), significantly longer neurites were observed on electrically stimulated electroconductive scaffolds. These results demonstrate that electrostimulation applied via an anatomically-mimetic, 3D-printed electroconductive scaffold drives neurite outgrowth and represents a promising approach for treatment of spinal cord injury.

The tungsten with high oxidation states (W⁶⁺) had been proved to effectively improve the electrochemical performance of ultrahigh-nickel (Ni ≥ 90 %) cathode materials due to the unique microstructures. However, the exat location and underlying action mechanism of tungsten are still not well-understood, and there have been no reports on in-situ modification from bulk to surface simultaneously for these novel cathode materials. Here, a novel integrated strategy is proposed for in-situ modification of LiNi_0.9Co_0.09W_0.01O₂ (NCW). Innovatively, the introduction of nano spinel phase and titanium pinned into the lattice further suppresses the anisotropic variation of unit cell and promotes the lithium-ion migration kinetics within the bulk. Additionally, the Li₂TiO₃ conductive network enhances migration kinetics across interface and protects the active material against electrolyte erosion. Furthermore, the combination of in-situ analysis and DFT calculation reveals the ordered distribution of tungsten and the suppression effects of titanium on phase transition and cobalt redox. Consequently, the titanium-modified NCW exhibits significantly improved electrochemical performance, such as capacity retention of 93.0 % at 1C after 500 cycles in pouch-type full-cell, along with stable lattice oxygen during operation.

In the domain of smart robotics, the refinement of tactile imaging constitutes a seminal element for enhancement of human–machine interaction (HMI) and enrichment of artificial intelligence (AI). This field is confronted with dual challenges of achieving high-sensitive pressure detection and precise localization of tactile stimuli. In response, the current research introduces a groundbreaking self-powered bimodal tactile imaging device (TID), featuring a configuration of high-dielectric thin film superimposed on laser-induced graphene (LIG) electrodes. This pioneering design is conceived to facilitate not only the detection of subtle pressure but also to support real-time visual recognition and intelligent control functionalities. The bimodal nature of the TID allows for the transformation of slight tactile inputs into both luminous triboelectrification-induced electroluminescence (TIEL) and measurable electrical signals, thereby seamlessly merging the realms of tactile perception and optical display. Leveraging the luminosity of TIEL, the TID adeptly achieves tactile imaging and immediate visual recognition, with its capabilities further enhanced through the integration of machine learning algorithms. Additionally, the TID exhibits a remarkable proficiency in precise tactile localization, through the analysis of voltage outputs initiated by delicate touching and sliding motions. Moreover, an advanced intelligent control system, predicated on the optical-electrical dual-modal sensing provided by the TID, has been developed. This system illustrates the synergistic fusion of visual recognition with accurate tactile localization, underscoring the substantial utility of the bimodal TID across diverse applications in HMI, AI, and intelligent robotic platforms and heralding new avenues for interactive and responsive robotic systems.

The creation of three dimensional (3D) structures out of two-dimensional (2D) materials while retaining their extraordinary mechanical and transport properties after processing is one of the current great challenges in materials sciences (Ruoff, 2008; Kong et al., 2019; Lin et al., 2019). Guided by density functional theory (DFT) and molecular dynamics (MD) simulations we found a successful route for a sustainable production of 3D metallic carbon materials that are synthesized from pristine 2D graphene flakes with hydrolyzed edges. The edge hydrolysis lead to strong geometrical anisotropy and self-organization in solution before processing. After processing we obtain a 3D carbon structure where 2D graphene flakes are crosslinked by carbon chains with aromatic groups at very mild annealing temperatures (∼150 °C), eliminating the constraints for achieving the in-situ preparation of conductive carbon structures. These 3D carbon structures preserve microscopic order but are macroscopically disordered, presenting physical properties of anisotropic metallic carbon with large Young modulus (E ≈ 20 GPa), and room temperature thermal (k ≈ 180 W/mK) and electrical (σ ≈ 300 kS/m) conductivities comparable to ordinary metals.

Body-centred cubic (BCC) transition metals tend to be brittle at low temperatures, which poses significant challenges in their processing and major concerns for damage tolerance. The brittleness is largely dictated by cleavage fracture at crack-tips and high lattice frictions of screw dislocation cores; the nature and control of which remain a puzzle after nearly a century. Here, we introduce a crystal geometry-based, semi-empirical material index χ, the energy difference between the BCC and face-centred-cubic structures, that guides engineering of crack-tip and screw dislocation core properties. The unstable stacking fault energy on $\left(110\right)$ planes and screw dislocation Peierls barrier have near-linear scaling with χ and the screw core transforms from non-degenerate to degenerate when χ drops below some thresholds in homogenized BCC alloys, as demonstrated in binary transition metal alloys. The index χ has its origin in crystal geometry and can be extended to finite temperatures; its value is related to entropy and valence electron concentrations, which can be quantitatively predicted by first-principles calculations and effectively tuned in solid solution alloys. The χ-model and computational approach provide a practical path to screening of favourable solutes and compositions for enhanced ductility and toughness in BCC alloys.

The commercialization of Ni-based catalysts in CO₂ dry reforming of methane (DRM) suffers from their quick deactivation. Here, we reveal each reaction pathway for DRM based on the Ni catalyst composition and geometry under working conditions, through one working platform combining in situ high resolution Cs corrected environmental transmission electron microscopy and electron energy-loss spectroscopy coupled with mass spectroscopy. The formation of Ni₃C has been found to inhibit the decomposition of CO₂ and CH₄, and to promote the formation of onion-like carbon to encapsulate the Ni catalysts, leading to the deactivation of the Ni-based catalysts. Designing the suitable supports or promoters to keep the Ni surface structure under Ni-NiO cycle can drive the simultaneously amorphous carbon deposition-consumption cycle and minimise the coke formation. This research is not only for developing coke resistance Ni catalysts in the DRM, but also significant for investigating many catalysis challenges both in research and engineering.