Nano Research最新文献

VX is a highly toxic organophosphorus nerve agent that the Chemical Weapons Convention classifies as a Schedule 1. In our previous study, we developed a method for detecting organophosphorus compounds using peptide self-assembly. Nevertheless, the self-assembly mechanisms of peptides that bind organophosphorus and the roles of each peptide residue remain elusive, restricting the design and application of peptide materials. Here, we use a multi-scale computational combined with experimental approach to illustrate the self-assembly mechanism of peptide-bound VX and the roles played by residues in different peptide sequences. We calculated that the self-assembly of peptides was accelerated after adding VX, and the final size of assembled nanofibers was larger than the original one, aligning with experimental findings. The atomic scale details offered by our approach enabled us to clarify the connection between the peptide sequences and nanostructures formation, as well as the contribution of various residues in binding VX and assembly process. Our investigation revealed a tight correlation between the number of Tyrosine residues and morphology of the assembly. These results indicate a self-assembly mechanism of peptide and VX, which can be used to design functional peptides for binding and hydrolyzing other organophosphorus nerve agents for detoxification and biomedical applications.

Oxygen reduction reaction (ORR) occurs at the cathode of electrochemical devices like fuel cells and in the Huron-Dow process, reducing oxygen to water or hydrogen peroxide. Over the past years, various electrocatalysts with enhanced activity, selectivity, and durability have been developed for ORR. However, an atomic-level understanding of how materials composition affects electrocatalytic performance has not yet been achieved, which prevents us from designing efficient catalysts based on the requirements of practical applications. This is partially because of the polydispersity of traditional catalysts and their unknown structure dynamics in the electrocatalytic reactions. Here we establish a full-spectrum of atomically precise and robust Au_xAg_25-x(MHA)18 (x = 0–25, and MHA = 6-mercaptohexanoic acid) nanoclusters (NCs) and systematically investigate their composition-dependent catalytic performance for ORR at the atomic level. The results show that, with the increasing number of Au atoms in Au_xAg_25-x(MHA)₁₈ NCs, the electron transfer number gradually decreases from 3.9 for Ag₂₅(MHA)₁₈ to 2.1 for Au₂₅(MHA)₁₈, indicating that the dominant oxygen reduction product alters from water to hydrogen peroxide. Density functional theory simulations reveal that the Gibbs free energy of OOH adsorption (Δ_GOOH*) on Au₂₅ is closest to the ideal ΔG_OOH* of 4.22 eV to produce H₂O₂, while Ag alloying makes the ΔG_OOH* deviate from the optimal value and leads to the production of water. This study suggests that alloy NCs are promising paradigms for unveiling composition-dependent electrocatalytic performance of metal nanoparticles at the atomic level.

The growing demand for electric vehicles highlights the need for energy storage solutions with higher densities, spotlighting Li metal anodes as potential successors to traditional Li-ion batteries (LIBs). Achieving longer calendar aging life for Li metal anodes is crucial for their practical use, given their propensity for corrosion due to a low redox potential, which leads to compromised cycling stability and significant capacity loss during storage. Recent research investigated that this susceptibility is mainly dependent on the surface area of Li metal anode and the properties of the solid electrolyte interphase (SEI), particularly its stability and growth rate. Our research adds to this understanding by demonstrating that the amount of Li plating is a key factor in its corrosion during open-circuit storage, as assessed across various electrolytes. We discovered that increasing the Li plating amount effectively reduces Coulombic efficiency (C.E.) loss during aging, due to a lower surface area-to-Li ratio. This implies that the choice of electrolyte for optimal storage life should consider the amount of Li plating, with higher capacities promoting better storage characteristics.

With the rapid development of science and technology, electronic devices are moving towards miniaturization and integration, which brings high heat dissipation requirements. During the heat dissipation process of a heating element, heat may spread to adjacent components, causing a decrease in the performance of the element. To avoid this situation, the ability to directionally transfer heat energy is urgently needed. Therefore, thermal interface materials (TIMs) with directional high thermal conductivity are more critical in thermal management system of electronic devices. For decades, many efforts have been devoted to the design and fabrication of TIMs with high-directional thermal conductivity. Benefiting from the advantage in feasibility, low-cost and scalability, compositing with thermal conductive fillers has been proved to be promising strategy for fabricating the high-directional thermal conductive TIMs. This review summarizes the present preparation technologies of polymer composites with high-directional thermal conductivity based on structural engineering of thermal conductive fillers, focusing on the manufacturing process, mechanisms, achievements, advantages and disadvantages of different technologies. Finally, we summarize the existing problems and potential challenges in the field of directional high thermal conductivity composites.

Self-powered wireless sensing system is particularly suitable for applications in intelligent manufacturing, smart healthcare etc. as it does not require an external power source. Triboelectric nanogenerator (TENG) is an emerging energy harvester that can be used to power self-powered wireless sensors. The latest achievement in this area is the instantaneous self-powered wireless sensor, where the electric energy generated by the TENG is injected directly into the inductor-capacitor (LC) resonator to generate a decaying oscillating signal with encoded sensing information. However, the frequency is lower (typically < 5 MHz) and the signal transmission distance is short (< 3 m) limited by the near-field magnetic coupling, restricting its widespread applications. In this research, we propose a self-powered long-distance wireless sensing platform which utilizes a surface acoustic wave (SAW) resonator based radio-frequency oscillator to convert TENG energy into a high frequency signal with sensing information encoded. With this system, the sensing signal can be easily transmitted through the antenna for long distance. An optimized system is designed and conditional influences are fully investigated. Results show this self-powered wireless sensor system can perform wireless sensing for force, temperature and vibration at a distance up to 50 m.

Flexible electrochromic devices (FECDs) are promising candidates for the next generation of wearable electronics due to their low operating voltage and energy consumption. For the flexible electrochromic devices, the electrolyte is an important component. Typically, the electrolyte needs to be formulated according to the device structure and usage scenario. A high-performance electrolyte involves consideration of many factors, including choosing the right polymer, solvent, curing agent, and ion type to satisfy particular device specifications. In this work, a ultraviolet-curable solid–liquid host–guest (UV-SLHG) electrolyte is developed. Several aspects of performance are improved by introducing the solid–liquid coexisting microstructure without changing the electrolyte formulation, including excellent adhesion, a 30% increase in tensile characteristics, and a seven-fold increase in ionic conductivity when compared to a fully cured solid-state electrolyte. More importantly, the unique advantage of SLHG electrolytes lies that the thickness will not change significantly during bending. The FECD made by using the UV-SLHG-based electrolyte sustained 10,000 bending cycles at the bending radius of 2.5 mm while maintaining outstanding optical modulation. A wearable ring-type ECD and a battery-free FECD wine label were made as demonstrators. The UV-SLHG strategy is not only suitable for the FECDs but also universally applicable to other electrolyte-based of flexible electronics such as flexible capacitors and batteries.

Advanced aqueous zinc-ion batteries have been greatly limited application caused by uncontrollable dendrite formation, hydrogen evolution and zinc metal corrosion, which can lead to quick failure of the battery and low Coulombic efficiency. Three-dimensional (3D) porous host strategy is available to limit zinc dendrite growth and electrode interfacial side reactions. Herein, an ingenious local levelling and macro stereo strategy is rationally designed as a Zn plating/stripping scaffold. The flexible 3D carbon cloth as the structural and conductive framework is coated by Ag-Cu-reduced graphene oxide (Ag-Cu-rGO) and Ketjen black. Benefiting from the uniformly dispersed zincophilic Ag on the surface of Cu nanoboxes, the anode suppresses hydrogen evolution side reactions and reduces local current density via more nucleation sites. In addition, rGO homogenizes both the ion flux and electric field at the electrode surface, resulting from high conductivity and large specific surface area of rGO. As a result, the fabricated Zn//Ag-Cu-rGO asymmetric cells exhibit stable voltage profiles for plating and striping 250 cycles, maintain nearly 100% Coulombic efficiency at 2 mA·cm⁻² and 1 mAh·cm⁻² as well as behave an extremely small nucleation overpotential of 34 mV and Ag-Cu-rGO@Zn symmetric cell presents highly uniform electric field with a superior lifespan over 2500 h at 1 mA·cm⁻² and 1 mAh·cm⁻², respectively. Meanwhile, this efficient Ag-Cu-rGO@Zn anode also enables a substantially stable Ag-Cu-rGO@Zn//V₂O₃ full cell over 2000 cycles. The work opens a new avenue of 3D host for durable and dendrite-free flexible aqueous zinc-ion batteries anode.

The photocatalytic oxygen reduction reaction (ORR), particularly the one-step two-electron (2e⁻) pathway, is a highly promising strategy for efficient and selective hydrogen peroxide (H₂O₂) synthesis. However, constructing efficient photocatalysts to achieve a one-step 2e⁻ ORR process remains a significant challenge. Herein, we developed an efficient photocatalyst by incorporating pyrimidine units into benzotrithiophene-based covalent organic framework (BTT-MD-COF), enabling the photosynthesis of H₂O₂ via the one-step 2e⁻ ORR pathway with O₂ and water. Under visible-light irradiation, BTT-MD-COF exhibited a high H₂O₂ production rate of up to 5691.2 µmol·h⁻¹·g⁻¹. Further experimental results and theoretical studies revealed that the introduction of pyrimidine units accelerates the separation of photoinduced electron–hole pairs and promotes Yeager-type O₂ adsorption, which alters the two-step 2e⁻ ORR process to the direct one-step 2e⁻ process. This work offers a new avenue to create metal-free catalysts for efficient photosynthesis of H₂O₂.

The development of electrocatalysts with high catalytic activity is conducive to enhancing polysulfides adsorption and reducing activation energy of polysulfides conversion, which can effectively reduce polysulfide shuttling in Li-S batteries. Herein, a novel catalyst NiCo-MoO_x/rGO (rGO = reduced graphene oxides) with ultra-nanometer scale and high dispersity is derived from the Anderson-type polyoxometalate precursors, which are electrostatically assembled on the multilayer rGO. The catalyst material possesses dual active sites, in which Ni-doped MoO_x exhibits strong polysulfide anchoring ability, while Co-doped MoO_x facilitates the polysulfides conversion reaction kinetics, thus breaking the Sabatier effect in the conventional electrocatalytic process. In addition, the prepared NiCo-MoO_x/rGO modified PP separator (NiCo-MoO_x/rGO@PP) can serve as a physical barrier to further inhibit the polysulfide shuttling effect and realize the rapid Li⁺ migration. The results demonstrate that Li-S coin cell with NiCo-MoO_x/rGO@PP separator shows excellent cycling performance with the discharge capacity of 680 mAh·g⁻¹ after 600 cycles at 1 C and the capacity fading of 0.064% per cycle. The rate performance is also impressive with the remained capacity of 640 mAh·g⁻¹ after 200 cycles even at 4 C. When the sulfur loading is 4.0 mg·cm⁻² and electrolyte volume/sulfur mass ratio (E/S) ratio is 6.0 μL·mg⁻¹, a specific capacity of 830 mAh·g⁻¹ is achieved after 200 cycles with a capacity decay of 0.049% per cycle. More importantly, the cell with NiCo-MoO_x/rGO@PP separator exhibits cycling performance under wide operating temperature with the reversible capacities of 518, 715, and 915 mAh·g⁻¹ after 100 cycles at −20, 0, and 60 °C, respectively. This study provides a new design approach of highly efficient catalysts for sulfur conversion reaction in Li-S batteries.

Gel polymer electrolytes (GPEs) with flexibility, easy processability, and low cost have been regarded as promising alternatives for conventional liquid electrolytes in next-generation sodium metal batteries (SMBs). However, GPEs often suffer from combustion risk and inferior interfacial compatibility toward Na metal anode, which severely limit their wide commercial applications. Here, a rational design of asymmetric fireproof GPE (AFGPE) modified with a boron-contained covalent organic framework (BCOF) on one side is developed through in-situ crosslinking polymerization process. Benefiting from the unique structure and composition, the resulting AFGPE exhibits high Na⁺ transference number, wide electrochemical window, excellent mechanical properties and high safety. Especially, the nanoscale BCOF layer with uniform nanochannels works as ion sieve that homogenizes Na⁺ flux during Na plating process, while the abundant Lewis-acid B sites can strongly capture counter anions and decrease space charge layer at anode side, thus promoting the uniform Na deposition to effectively suppress dendrite growth. Consequently, the Na/AFGPE/Na symmetric cells demonstrate remarkable cycling stability for over 1200 h at 0.1 mA·cm^-2, and the solid-state SMBs exhibit outstanding cycling properties and rate capability, delivering a high capacity retention of 96.4% under current density of 1 C for over 1000 cycles.