Nano Materials Science最新文献

The CO₂ electroreduction reaction (CO₂RR) is a promising approach of using renewable electricity to synthesize fuels and value-added chemicals. At present, Cu is generally considered to be the major monometallic catalyst capable of producing multicarbon products (C₂₊) with high current densities from the CO₂RR, but it still suffers from the low activity and high overpotential. The challenge of sluggish CO₂RR kinetics can be overcome by developing efficient Cu-based catalysts, which undergo the dynamic evolution during the reaction process. The dynamic evolution of the Cu-based catalysts taking place under working conditions makes it difficult to study the structure-activity correlation and reaction mechanism present during CO₂RR. Recently, a number of important works have observed and revealed the dynamic evolution process of Cu-based catalysts by operando characterization techniques. This aspect, however, remains less summarized and prospected in the CO₂RR literature. In this Review, we summarize the dynamic evolution of Cu-based catalysts during the CO₂RR from aspects of structure, composition and oxidation state. We highlight the correlations between evolution behaviors and catalytic properties. Then, we discuss the dynamic deactivation process of Cu-based catalysts during CO₂RR, including metal impurities contamination and carbon accumulation. In particular, we introduce recent advancements in in situ characterization techniques those are employed to probe the dynamic evolution under operating conditions. We end the Review by outlining the challenges and offering personal perspectives on the future development opportunities in this field.

The aim of this work was to improve the thermal conductivity and electromagnetic shielding of the leakage proof phase change materials (PCMs), in which a polyrotaxane (PLR) was used as a support material to encapsulate PEG 1k or PEG 6k and MXene as multi-functional filler. The PCMs can be processed conveniently by a hot press and the PEG 1k containing samples showed excellent flexibility. We conducted a systematic evaluation of the phase transition behavior of the material, thermal conductivity and electromagnetic shielding performance tests. Notably, the PCMs achieved a high enthalpy values (123.9–159.6 ​J/g). The PCMs exhibited an increase of 44.3 ​%, and 137.5 ​% in thermal conductivity values with higher MXene content (5 ​wt%) for PLR-PEG6k and PLR-PEG1k, respectively, and show high shape stability and no leakage during and after phase transition. The introduction of MXene can significantly improve the electromagnetic shielding performance of PCM composites. Typically, higher conductive samples (samples which contain high MXene contents) offer a higher EMI SE shielding, reaching a maximum of 4.67 ​dB at 5.6 ​GHz for PLR-1K-MX5. These improvements solve the main problems of organic PEG based PCMs, thus making PLR-PEG-MXene based PCMs good candidates for thermoregulators of both solid-state disks and smart phone. It is worth pointing out that the sample PLR-1k-MX5 can decrease 4.3 ​°C of the reference temperature during cellphone running. Moreover, the temperature of the protecting sheet in the simulated solid state disk with PCM was significantly lower (showing a decreasing of 7.9 ​°C) compared with the blank sample.

Inspired by the skin structure, an asymmetric wettability tri-layer nanofiber membrane (TNM) consisting of hydrophilic inner layer loaded with lidocaine hydrochloride (LID), hydrophobic middle layer with ciprofloxacin (CIP) and hydrophobic outer layer has been created. The hydrophobic outer layer endows the TNM with waterproof function and anti-adhesion from contaminants. The hydrophobic middle layer with CIP preserves long-term inhibition of bacteria growth and the hydrophilic inner layer with LID possesses optimal water-absorbing capacity and air permeability. The TNM dramatically elevates the water contact angles from 10° (inner layer) to 120° (outer layer), indicating an asymmetric wettability, which could directionally transport wound exudate within the materials and meanwhile maintain a comfortable and moist environment to promote wound healing. Furthermore, the sequential release of LID and CIP could relieve pain rapidly and achieve antibacterial effect in the long run, respectively. In addition, the TNM shows superior biocompatibility towards L929 ​cells. The in vivo results show the TNM could prevent infection, accelerate epithelial regeneration and significantly accelerate wound healing. This study indicates the developed TNM with asymmetrical wettability and synergetic drug release shows great potential as a wound dressing in clinical application.

This study explores the dynamic interaction between environmentally sustainable plasma enhancer and quencher agents during the incorporation of SiO₂ into a TiO₂ layer, with the primary objective of simultaneously augmenting protective and bioactive attributes. This enhancement is realized through the synergistic utilization of Tetraethyl orthosilicate (TE) and Stevia (ST) within a plasma-assisted oxidation process. To achieve this goal, Ti–6Al–4V alloy underwent oxidation in an electrolyte solution containing acetate-glycerophosphate, with the addition of TE and ST separately and in combination. TE, as a silicon oxide (SiO₂) precursor, facilitates the creation of a calcium-rich, rough, porous layer by undergoing hydrolysis to generate silanol groups (Si–OH), which subsequently condense into silicon-oxygen-silicon (Si–O–Si) bonds, resulting in SiO₂ formation. In contrast, ST acts as a plasma quencher, absorbing highly reactive plasma species during the oxidation process, reducing energy levels, and diminishing sparking intensity. The combination of TE and ST results in moderate sparking, balancing Stevia's quenching effect and TE's sparking influence. As a result, this coating exhibits enhanced corrosion resistance and bioactivity compared to using either ST or TE alone. The study highlights the potential of this synergistic approach for advanced TiO₂-based coatings.

CO₂ reformation of methane (CRM) and CO₂ methanation are two interconnected processes with significant implications for greenhouse gas reduction and sustainable energy production for industrial purposes. While Ni-based catalysis suffers from poor stability due to coke formation or sintering, we report a super stable remedy. The active sites of mesoporous MgO were loaded using wet impregnation. The incorporation of Ni and promoters altered the physical features of the catalysts. Sm–Ni/MgO showed the smallest crystallite size, specific surface area, and pore volume. The Sm–Ni/MgO catalyst was selected as the most suitable candidate for CRM, with 82 ​% CH₄ and H₂/CO ratio of approximately 100 ​% and also for CO₂ methanation with the conversion of carbon dioxide (82 ​%) and the selectivity toward methane reaches 100 ​% at temperatures above 300 ^ᵒC. Furthermore, the Sm–Ni/MgO catalyst was stable for 900 ​min of continuous reaction, without significant carbon deposition. This stability was largely due to the high oxygen mobility on the catalyst surface in the presence of Sm. Overall, we demonstrated the efficacy of using promoted Ni catalysts supported by mesoporous magnesia for the improved reformation of greenhouse gases.

Surface modifications can introduce natural gradients or structural hierarchy into human-made microlattices, making them simultaneously strong and tough. Herein, we describe our investigations of the mechanical properties and the underlying mechanisms of additively manufactured nickel–chromium superalloy (IN625) microlattices after surface mechanical attrition treatment (SMAT). Our results demonstrated that SMAT increased the yielding strength of these microlattices by more than 64.71% and also triggered a transition in their mechanical behaviour. Two primary failure modes were distinguished: weak global deformation, and layer-by-layer collapse, with the latter enhanced by SMAT. The significantly improved mechanical performance was attributable to the ultrafine and hard graded-nanograin layer induced by SMAT, which effectively leveraged the material and structural effects. These results were further validated by finite element analysis. This work provides insight into collapse behaviour and should facilitate the design of ultralight yet buckling-resistant cellular materials.

For improving the actuation performance at low electric fields of dielectric elastomers, achieving high dielectric constant (ɛ_r) and low modulus (Y) simultaneously has been targeted in the past decades, but there are few ways to accomplish both. In contrast to the classical strategies such as incorporating plasticizers or ceramic to prepare the silicon-based dielectric elastomers, here, blending an amino-complexed hybrid (polyethyleneimine (PEI)-Ag) with polydimethylsiloxane (PDMS) elastomer is reported as an alternative strategy to tailor the ɛ_r and Y. PEI-Ag not only exhibits excellent dielectric enhancement properties but also minimizes the PDMS crosslinking through amino-complexed reaction between PEI and Pt catalysts. The prepared dielectric elastomers have a ɛ_r of 7.2 @ 10³ ​Hz and Y of 1.14 ​MPa, leading to an actuation strain of 22.27 ​% at 35 ​V/μm. Hence, incorporating such novel hybrids based on dual amino-complexed effect on both matrix and particles sufficiently promotes the actuated performance of dielectric elastomers.

The hybridization of metal-organic framework (MOF) with inorganic layers would lead to the discovery of novel hybrid materials that can provide a compelling strategy for enhancing its photocatalytic and electrochemical response. In the present study, a highly efficient multifunctional hybrid material was developed by exploiting the defective layer formed on AZ31 Mg alloy through plasma electrolytic oxidation (PEO) as a nucleation and growth site for Co-MOF. The concentrations of the organic linker 2-Methylimidazole (2,MIm) and cobalt nitrate as a source of Co²⁺ ions were varied to control the growth of the obtained Co-MOF. Lower concentrations of the 2, MIm ligand favored the formation of leaf-like MOF structures through an anisotropic, two-dimensional growth, while higher concentrations led to rapid, isotropic nucleation and the creation of polyhedral Co-MOF structures. The sample characterized by polyhedral Co-MOF structures exhibited superior electrochemical stability, with the lowest corrosion current density (3.11 ​× ​10⁻⁹ A/cm²) and the highest top layer resistance (2.34 ​× ​10⁶ ​Ω ​cm²), and demonstrated outstanding photocatalytic efficiency, achieving a remarkable 99.98 ​% degradation of methylene blue, an organic pollutant, in model wastewater. To assess the active adsorption sites of the Co-MOF, density functional theory (DFT) was utilized. This study explores the changes in morphologies of the coatings of Co-MOF with the change of solution concentration to form coatings with enhanced properties on the metallic substrate, which could establish the groundwork for the development of next-generation multifunctional frameworks with diverse applications.