Science China Materials最新文献

Ischemic stroke is on the rise worldwide, and stent intervention is gradually becoming one of the effective treatments. Biodegradable Mg-Zn-Y-Nd alloy (ZE21B) has good mechanical properties and biocompatibility, and has a good application prospect in vascular scaffolds. However, it still suffers from poor corrosion resistance, insufficient endothelialization, and blood-brain barrier (BBB) remodeling. Previously, it was found that constructing a bionic coating of barnacle gum protein cp19k on the surface of ZE21B by electrostatic spraying could improve its corrosion resistance and pro-endothelialization ability. Therefore, we considered piggybacking sulfonated hyaluronic acid nanoparticles (NP@S-HA) on the coating, which inherited the excellent anticoagulant and anti-inflammatory properties of S-HA on the basis of its improved corrosion resistance. The coatings were evaluated by electrochemistry, static immersion corrosion, in vitro blood experiments, and cellular experiments. Collectively, the cp19k/NP@S-HA coating demonstrated an average corrosion resistance enhancement of approximately 40.6% relative to the uncoated ZE21B. Cp19k/NP@S-HA was able to effectively improve the proliferation and migration of endothelial cells, inhibit the proliferation and regulate the contractile phenotype of smooth muscle cells, inhibit macrophage (MA) adherence, regulate the M2 phenotype of MAs, reduce the expression of the inflammatory factor tumor necrosis factor-α (TNF-α), and inhibit fibroplasia. In summary, the composite coatings developed in this study provide an effective strategy for surface modification of magnesium alloys in cerebrovascular applications, which has a broad application prospect.

β-Ga₂O₃ is a promising candidate for solar-blind ultraviolet photodetection owing to its suitable bandgap of approximately 4.9 eV, excellent photoresponse characteristics, and high stability. However, the lack of a sufficient driving force within the material leads to extensive bulk charge recombination, limiting its photocurrent and thus posing significant challenges in designing high-performance Ga₂O₃-based photodetection. In this study, we propose a gradient doping strategy to achieve a Sn-doping concentration gradient along the β-Ga₂O₃ film thickness. By combining sol–gel synthesis with rapid thermal annealing, a spatially graded band structure with a full-space built-in electric field is constructed, which increases the width of band bending over a large region and is crucial for significantly enhancing carrier separation and transport in the bulk. The resulting gradient Sn-doped β-Ga₂O₃ enables exceptional photoelectric performance without an external bias under 254 nm irradiation, including a superior responsivity of 66.88 mA W⁻¹, a high detectivity of 8.12 × 10¹¹ Jones, and a fast rise/decay time of 79/65 ms, outstanding most existing similar reported photoelectrochemical (PEC) type optoelectronic devices. Additionally, the device exhibits excellent long-term stability and enables high-resolution underwater ultraviolet imaging. This study demonstrates that the gradient doping strategy provides a feasible approach for enhancing the PEC performance of β-Ga₂O₃ photoelectrodes.

Fused silica (SiO₂) exhibits exceptional thermal stability and dielectric properties, making it an attractive material for aerospace and military applications. However, its relatively poor mechanical performance has limited its widespread practical utilization. This study proposed an innovative approach to fabricate SiO₂-hexagonal boron nitride (hBN) composite ceramics via spark plasma sintering (SPS), leveraging the high-temperature phase transformation of cBN to introduce randomly oriented hBN as a reinforcing phase within the SiO₂ matrix. The randomly oriented hBN nanoplates allow cracks to propagate along stronger grain boundaries, rather than along weaker interlayers of hBN, significantly improving the overall strength and fracture toughness of the composite. The maximum flexural strength and fracture toughness achieved are 183.4 MPa and 2.06 MPa m^1/2 respectively, which are 3.6 times and 4 times that of fused SiO₂. Concurrently, the composites exhibit low dielectric constants (ε = 3.58–3.69) and dielectric losses (tan δ < 0.0087) at 1 MHz. This work successfully enhanced the mechanical performance of fused SiO₂ while preserving its excellent dielectric characteristics, opening new possibilities for its potential applications in advanced structural and functional fields.

Wearable sensors have attracted significant attention due to their superior sensitivity, safety, and adaptability compared with conventional detection technologies. However, developing sustainable sensing materials that combine excellent performance with environmental friendliness remains a significant challenge. In this study, Juncus effusus (JE), a natural fiber featuring a unique internal three-dimensional (3D) network structure, was employed as the substrate. Conductive polyaniline was loaded onto the JE structure to impart electrical conductivity, and Ecoflex encapsulation provided high elasticity. Based on this approach, a JE-based resistive flexible sensor (PHE-JE) was successfully fabricated. The PHE-JE sensor exhibits high stability under various strain conditions, along with excellent flexibility and durability. Moreover, benefiting from its complex 3D structure and synergistic material interactions, the PHE-JE sensor enables accurate detection of diverse motion types, showing promising potential for future wearable sensing applications.

Polar two-dimensional (2D) perovskites with their excellent semiconductor properties, intrinsic anisotropy, and bulk photovoltaic effect, have emerged as promising candidates for Self-driven polarization-sensitive photo-detectors. However, these self-driven polarized detectors typically require fabrication along the spontaneous polarization direction to maintain the device’s operation in the self-driven mode, which imposes additional limitations. Herein, we demonstrate multidirectional self-driven polarization-sensitive photodetection by constructing 2D perovskite-based asymmetric contact devices, Ag/2D perovskite/C. The built-in electric field, originating from the difference in work functions, acts as the driving force for the separation and transport of photogenerated carriers. Notably, this approach does not necessitate a specific direction, thereby enabling multidirectional self-driven photodetection. Under excitation by linearly polarized light, our devices exhibit impressive polarization-sensitive discrimination in multiple directions, achieving polarization ratios of 3.3 and 3.1 along the a and b-axes, respectively. Our work enriches the approaches enabling self-driven polarization-sensitive photodetection, free from the previous limitations.

Direct regeneration is considered a sustainable solution to the issue of resource recycling and the environmental pollution caused by discarded lithium-ion batteries (LIBs). However, the direct regeneration of spent LiFePO₄ cathode materials still faces a formidable challenge that the irregular strains induced by the irreversible FePO₄ phase after several charge and discharge cycles hinder the regenerative replenishment of Li⁺. This work proposes a lattice stress modulation strategy that reduces FePO₄ phase into Fe₂P₂O₇ phase (reduction of unit cell volume from 271.7 to 122.6 ų), which releases the residual stress, paving continuous transport channels for Li⁺. In addition, the phase transformation reconstructs the FeO₆ octahedra, significantly decreasing the migration energy barrier of ions within the lattice. Ultimately, the steric effect is synergistically weakened, facilitating the replenishment of Li⁺ and the elimination of Li-Fe anti-site defects. The regenerated LiFePO₄ cathodes outperform commercial cathodes (80.2% capacity retention after 1000 cycles at 2 C). This work establishes fundamental principles for the pretreatment stage of the direct regeneration process and provides a paradigm shifting solution for sustainable LIBs recycling technology.

Multi-site coupling is a promising strategy for developing highly efficient and CO-resistant hydrogen oxidation reaction (HOR) catalysts for proton exchange membrane fuel cells (PEMFCs). However, designing multifunctional synergistic schemes for single-atom sites remains a significant challenge. Herein, we propose a dual-template-confined oxophilic engineering strategy to construct well-dispersed iridium-nickel (IrNi) atomic dimers adjacent to IrNi nanoclusters on porous nitrogen-doped carbon (IrNi_Dimer/NC1.8-PNC). The paired IrNi dimer features an asymmetric Ir-N₃ configuration coordinated with heteroatomic Ni-N₃O via an N-bridge. Remarkably, IrNi_Dimer/NC1.8-PNC exhibits a ∼23-fold enhancement in mass activity (4.36 A mg^−1Ir at 20 mV) and 5-fold longer stability compared to benchmarking Pt/C toward HOR, while achieving a high rated power density of 1.18 W cm⁻² in PEMFC anode applications. Furthermore, IrNi_Dimer/NC1.8-PNC demonstrates superior CO tolerance over monometallic Ir and Pt/C in both half-cell and full-cell devices. Combined experimental and density functional theory studies reveal that oxophilic Ni modulates the electronic environment of Ir through alloying and dimer interactions, thereby enhancing HOR activity. Importantly, the asymmetric IrNi dimer enables efficient CO* and OH* co-adsorption while facilitating CO₂* desorption, synergistically mitigating CO poisoning and improving atom utilization efficiency. This work provides a design strategy and fundamental insights for multi-site synergistic catalysts in PEMFC anodes.

Conductive hydrogel-based stretchable electronics have been extensively investigated, among which strain sensors are the most prominently studied. While the mechanical properties significantly affect the performance of these devices, the systematic correlation between specific mechanical parameters and sensing performance remains rarely explored. This work compares the influences of Young’s modulus and mechanical hysteresis on the sensing performance between highly entangled PAM-Li and double-network PAM-Li-Agar-3 strain sensors. Owing to the brittle agar network, which imparts a higher Young’s modulus and pronounced mechanical hysteresis to the double-network PAM-Li-Agar-3 hydrogel, the corresponding sensor requires a greater driving force for deformation and yields signals with poor reproducibility. In comparison, the PAM-Li hydrogel, characterized by highly entangled polymer chains, exhibits a lower Young’s modulus and negligible mechanical hysteresis. Consequently, signals from the PAM-Li strain sensor demonstrate enhanced sensitivity and stability. Therefore, this work demonstrates that a low Young’s modulus and minimal mechanical hysteresis are critical factors for achieving superior sensing performance in strain sensors, as systematically validated through comparative analyses across diverse application scenarios.

Electrochemical CO₂ reduction reaction (CO₂RR) offers an attractive approach to produce chemicals and fuels, especially for the value-added multicarbon (C₂₊) products. However, due to the strong competition reactions of hydrogen evolution and mono-carbon production, precise modulation of reaction pathways at the molecular level is challenging. Here, we propose a dual-confinement effect of CO₂ reactant and *CO intermediate in CO₂RR, induced by tuning the pore configuration of reconstructed covalent organic framework (RC-COF), which effectively improves C₂₊ selectivity. Attributed to the dual-confinement effect, we achieved a maximum C₂₊ selectivity of 67.0% at 500 mA cm⁻² over the COF modified Cu electrode, which maintains a high carbon products Faradaic efficiency over 90% across a board current density range (100–500 mA cm⁻²) in acidic electrolyte. Experimental and theoretical results prove that the highly crystalline RC-COF-1 with ordered micro-pores has advantages in modulating the adsorption and diffusion of reactants and intermediates. Our study provides deep insights into microenvironment modulation in CO₂RR, and underscores the critical role of COF pore configuration for other heterogeneous catalysis reactions.