Nano Research最新文献

In this study, we successfully synthesized silicon nanotubes (Si-NTs) and silicon nanowires (Si-NWs) in a controllable manner using a catalyst- and template-free method through the direct electrolysis of SiO₂ in a molten CaCl₂-CaO system, while also proposing a novel formation mechanism for Si-NTs. Si-NWs are formed through electro-deoxidation when the cell voltage is within the range of CaO decomposition voltage and SiO₂ decomposition voltage. By subsequently adjusting the voltage to a value between the decomposition potentials of CaCl₂ and CaO, in-situ electro-deoxidation of CaO takes place on the surface of the synthesized Si-NWs, leading to the formation of a Ca layer. The formation of Ca-Si diffusion couple leads to the creation of vacancies within the Si-NWs, as the outward diffusion rate of Si exceeds the inward diffusion rate of Ca. These differential diffusion rates between Si and Ca in a diffusion couple exhibit an analogy to the Kirkendall effect. These vacancies gradually accumulate and merge, forming large voids, which ultimately result in the formation of hollow SiCa-NTs. Through a subsequent dealloying process, the removal of the embedded calcium leads to the formation of Si-NTs. Following the application of a carbon coating, the Si-NTs@C composite showcases a high initial discharge capacity of 3211 mAh·g⁻¹ at 1.5 A·g⁻¹ and exhibits exceptional long-term cycling stability, maintaining a capacity of 977 mAh·g⁻¹ after 2000 cycles at 3.0 A·g⁻¹.

Highly dispersed Pd/N-doped carbon dots (Pd/NCDs) were successfully immobilized in the mesoporous channels of amino-functionalized dendritic mesoporous silica nanospheres (NMS). The synthesized Pd/NCDs@NMS catalyst exhibits outstanding performance in the catalytic reduction of 4-nitrophenol (4-NP), achieving a turnover frequency of 1461.8 mol·mol_Pd⁻¹·h⁻¹, with the conversion rate remaining above 80% after 11 cycles. Experiments and density functional theory calculations reveal that the NCDs significantly affect the electronic structure of Pd nanoparticles, leading to changes in the energy barriers for the adsorption of 4-NP at the Pd sites and the conversion of 4-NP reaction intermediates, which is a key factor contributing to the catalytic performance. This study offers a new strategy for synthesizing carbon-dot-modified metal-based catalysts.

Oxygen evolution reaction (OER) plays a crucial role in developing energy conversion and adjusting electronic structure of the electrocatalysts can effectively improve the catalytic activity and stability. However, it is a challenge to adjust the electronic structure on two-dimensional iridium dioxide nanosheets (IrO₂ NS), which have the advantages of high atom utilization. Here, we regulate the surface properties of IrO₂ NS through sulfonated carbon dots (SCDs) to promote the OER catalytic process. The catalyst IrO₂ NS/SCDs-2 exhibited excellent catalytic activity with a lower overpotential of 180 mV than IrO₂ NS (230 mV) at the current density of 10 mA·cm⁻² in a 0.5 M H₂SO₄ solution. And after 160 h of stability testing, the overpotential of IrO₂ NS/SCDs-2 only decreased by 4 mV. Moreover, transient potential scanning test can visually demonstrate that the addition of SCDs improves the conductivity of the catalyst and increases the electron transfer rate.

The off-stoichiometric iron-based phosphate (Na_3.12Fe_2.44(P₂O₇)₂, denoted as Na_3.12) as a low cost and high structure stability cathode material has been widely studied for sodium-ion batteries (SIBs). However, the lower theoretical specific capacity (117 mAh·g⁻¹) has seriously limited its practical application. In this work, we incorporate varying proportion of sodium-iron phosphate (NaFePO₄) into the Na_3.12 to form a series of new high specific capacity mixed-phosphates Na_3.12+xFe_2.44+x(P₂O₇)₂(PO₄)_x cathode materials for SIBs. After optimizing the introduction amount of NaFePO₄ into Na_3.12, the practical reversible of Na_3.12+xFe_2.44+x(P₂O₇)₂(PO₄)_x increased from 92 to 125.2 mAh·g⁻¹. The nano-size Na_5.12Fe_4.44(P₂O₇)₂(PO₄)₂ cathode material shows a reversible specific capacity of 125.2 mAh·g⁻¹ at 0.1 C in SIBs. Even at 60 C, it still exhibits a reversible specific capacity of 93.3 mAh·g⁻¹ and keeps a capacity retention ratio of 87% after 3000 cycles at 20 C. Thereby, we present a novel approach to design a series of off-stoichiometric mixed-phosphates cathode materials for SIBs.

It is highly desirable to design efficient and stable hydrogen evolution reaction (HER) and oxygen evolution/reduction reaction (OER/ORR) electrocatalysts for the development of renewable energy technologies. Herein, density functional theory (DFT) calculations were conducted to systematically investigate a series of TMN_xO_4−x-HTT (TM = Fe, Co, Ni, Ru, Rh, Pd, Ir and Pt; HTT = hexahydroxy tetraazanaphthotetraphene) analogs of two-dimensional (2D) conductive metal-organic frameworks (MOFs) as potential electrocatalysts for the HER, OER and ORR. The thermodynamic and electrochemical stability simulations suggest that these designed catalysts are stable. Remarkably, CoO₄-HTT, RhN₃O₁-HTT and IrN₃O₁-HTT are predicted to be the most promising catalysts for the HER, OER and ORR, respectively, surpassing the catalytic activity of corresponding benchmark catalysts. The volcano plots were established based on the scaling relationship of adsorption Gibbs free energy of intermediates. The results reveal that regulating combinations of metal active centers and local coordination environments could effectively balance the interaction strength between intermediates and catalysts, thus achieving optimal catalytic activity. Our findings not only opt for the promising HER/OER/ORR electrocatalysts but also guide the design of efficient electrocatalysts based on 2D MOFs materials.

The facile reconfiguration of phases plays a pivotal role in enhancing the electrocatalytic production of H₂ through heterostructure formation. While chemical methods have been explored extensively for this purpose, plasma-based techniques offer a promising avenue for achieving heterostructured nano-frameworks. However, the conventional plasma approach introduces complexities, leading to a multi-step fabrication process and challenges in precisely controlling partial surface structure modulation due to the intricate interaction environment. In our pursuit of heterostructures with optimized oxygen evolution reaction (OER) behavior, we have designed a facile auxiliary insulator-confined plasma system to directly attain a Ni₃N–NiO heterostructure (hNiNO). By meticulously controlling the surface heating process during plasma processing, such approach allows for the streamlined fabrication of hNiNO nano-frameworks. The resulting nano-framework exhibits outstanding catalytic performance, as evidenced by its overpotential of 320 mV at a current density of 10 mA·cm⁻², in an alkaline environment. This stands in stark contrast to the performance of NiO-covered Ni₃N fabricated using the conventional plasma method (sNiNO). Operando plasma diagnostics, coupled with numerical simulations, further substantiates the influence of surface heating due to auxiliary insulator confinement of the substrate on typical plasma parameters and the formation of the Ni₃N–NiO nanostructure, highlighting the pivotal role of controlled surface temperature in creating a high-performance heterostructured electrocatalyst.

The current spotlight of cancer therapeutics is shifting towards personalized medicine with the widespread use of monoclonal antibodies (mAbs). Despite their increasing potential, mAbs have an intrinsic limitation related to their inability to cross cell membranes and reach intracellular targets. Nanotechnology offers promising solutions to overcome this limitation, however, formulation challenges remain. These challenges are the limited loading capacity (often insufficient to achieve clinical dosing), the complex formulation methods, and the insufficient characterization of mAb-loaded nanocarriers. Here, we present a new nanocarrier consisting of hyaluronic acid-based nanoassemblies (HANAs) specifically designed to entrap mAbs with a high efficiency and an outstanding loading capacity (50%, w/w). HANAs composed by an mAb, modified HA and phosphatidylcholine (PC) resulted in sizes of ~ 100 nm and neutral surface charge. Computational modeling identified the principal factors governing the high affinity of mAbs with the amphiphilic HA and PC. HANAs composition and structural configuration were analyzed using the orthogonal techniques cryogenic transmission electron microscopy (cryo-TEM), asymmetrical flow field-flow fractionation (AF4), and small-angle X-ray scattering (SAXS). These techniques provided evidence of the formation of core-shell nanostructures comprising an aqueous core surrounded by a bilayer consisting of phospholipids and amphiphilic HA. In vitro experiments in cancer cell lines and macrophages confirmed HANAs’ low toxicity and ability to transport mAbs to the intracellular space. The reproducibility of this assembling process at industrial-scale batch sizes and the long-term stability was assessed. In conclusion, these results underscore the suitability of HANAs technology to load and deliver biologicals, which holds promise for future clinical translation.

Perovskite solar cells have shown great potential in the field of underwater solar cells due to their excellent optoelectronic properties; however, their underwater performance and stability still hinder their practical use. In this research, a 1H,1H,2H,2H-heptadecafluorodecyl acrylate (HFDA) anti-reflection coating (ARC) was introduced as a high-transparent material for encapsulating perovskite solar modules (PSMs). Optical characterization results revealed that HFDA can effectively reduce reflection of light below 800 nm, aiding in the absorption of light within this wavelength range by underwater solar cells. Thus, a remarkable efficiency of 14.65% was achieved even at a water depth of 50 cm. And, the concentration of Pb²⁺ for HFDA-encapsulated film is significantly reduced from 186 to 16.5 ppb after being immersed in water for 347 h. Interestingly, the encapsulated PSMs still remained above 80% of their initial efficiency after continuous underwater illumination for 400 h. Furthermore, being exposed to air, the encapsulated PSMs maintained 94% of their original efficiency after 1000 h light illumination. This highly transparent ARC shows great potentials in enhancing the stability of perovskite devices, applicable not only to underwater cells but also extendable to land-based photovoltaic devices.

Solar-driven photo-thermal catalytic CO₂ methanation reaction is a promising technology to alleviate the problems posed by greenhouse gases emissions. However, designing advanced photo-thermal catalysts remains a research challenge for CO₂ methanation reaction. In this work, a series of ABO₃ (A = lanthanide, B = transition metal) perovskite catalysts with Ce-substituted LaNiO₃ (La_1−xCe_xNiO₃, x = 0, 0.2, 0.5, 0.8, 1) were synthesized for CO₂ methanation. The La_0.2Ce_0.8NiO₃ exhibited the highest CH₄ formation rate of 258.9 mmol·g⁻¹·h_cat⁻¹, CO₂ conversion of 55.4% and 97.2% CH₄ selectivity at 300 °C with the light intensity of 2.9 W·cm⁻². Then the catalysts were thoroughly analyzed by physicochemical structure and optical properties characterizations. The partial substitution of the A-site provided more active sites for the adsorption and activation of CO₂/H₂. The sources of the active sites were considered to be the oxygen vacancies (O_v) created by lattice distortions due to different species of ions (La³⁺, Ce⁴⁺, Ce³⁺) and exsolved Ni⁰ by H₂ reduction. The catalysts have excellent light absorption absorbance and low electron–hole (e⁻/h⁺) recombination rate, which greatly contribute to the excellent performance in photo-thermal synergistic catalysis (PTC) CO₂ methanation. The results of in situ irradiated electron paramagnetic resonance spectrometer (ISI-EPR) and ISI-X-ray photoelectron spectroscopy (XPS) indicated that the aggregation of unpaired electrons near the defects and Ni metal (from La and Ce ions to O_v and Ni⁰) accelerated adsorption and activation of CO₂/H₂. At last, the catalyst properties and structure were correlated with the proposed reaction mechanism from the in situ diffuse reflection infrared Fourier transform spectrum (DRIFTS) measurements. The in situ precipitation of the B-site enhanced the dispersion of Ni, while its enriched photoelectrons upon illumination further promote hydrogen dissociation. More H* spillover accelerated the rate-determining step (RDS) of HCOO* hydrogenation. This work provides the theoretical basis for the development of catalysts and industrial application.

Implantable cardiovascular devices have revolutionized the management of cardiovascular diseases, significantly enhancing patients’ quality of life. With the increasing demand of cardiac implantable electronic devices, the imperative for novel device development is evident. This review article first elaborates the mechanisms underlying foreign body response and infection, elucidating the complex interplay between implanted constructs and host tissues. The discussion then focuses on current advancements in materials science and engineering aimed at mitigating these challenges. Material innovations, such as drug-eluting materials, surface modifications, and biomimetic materials, are explored as strategies to modulate these responses and to prevent fibrotic or thrombotic complications and infection. Finally, future directions in materials development for implantable cardiovascular devices are introduced. By addressing safety and patency concerns through innovative material strategies, this article aims to guide the research and development of advanced materials for both current and future cardiovascular implantable devices, ultimately improving patient outcomes and advancing cardiovascular disease treatment.