Nanoscale Advances最新文献

Electrolytic glucose oxidation has garnered great interest in energy-saving hydrogen generation. However, high charge-transfer resistance and inefficient active centers have been recognized as the primary issues for poor electrochemical performance. In this study, for the first time, we offer a novel defect-rich CeO _x /β-Ni(OH)₂ composite nanosheet-decorated Ni foam electrocatalyst (denoted as Ce@NF-GA), synthesized via a unique hydrothermal approach under the co-participation of glycerol and acetic acid. The employed characterizations unveil a close CeO _x /β-Ni(OH)₂ interfacial contact and numerous surface defects (e.g., oxygen vacancies). Such features significantly result in a significant enhancement in the electrocatalytic glucose oxidation reaction. Indeed, the obtained Ce@NF-GA catalyst demands a low potential of 1.31 V to reach a current density of 10 mA cm^-2. Additionally, Ce@NF-GA exhibited a high charge transportation capability and stability for 3 consecutive working cycles, corresponding to an outstanding Faradaic efficiency of ∼100% toward hydrogen production. The exploration of such novel material discloses a potential pathway for the utilization of Ce-based electrocatalysts for the energy-saving hydrogen production-coupled glucose oxidation reaction.

Recently, interest has surged in the environmental and biomedical applications of two-dimensional transition metal borides, commonly referred to as MBenes. These materials have emerged as promising candidates for energy storage devices, such as batteries and supercapacitors. Additionally, MBenes have shown remarkable catalytic activity due to their high surface area and tunable electronic properties. They exhibit significant promise in various catalytic applications, particularly in nitrogen reduction reactions (NRRs), electrocatalytic conversion of nitrogen oxides, and several electrochemical reactions such as the oxygen evolution reaction (OER), oxygen reduction reaction (ORR), and hydrogen evolution reaction (HER). Notably, MBenes have shown great potential in water treatment and pollutant removal applications, such as desalination and water purification. Their high water permeability, ion selectivity, and excellent stability make them suitable for efficient water treatment processes. On the other hand, MBenes are emerging as versatile materials with significant potential in various biomedical applications, particularly in biosensing, cancer therapy, and the treatment of neurodegenerative diseases. However, several challenges hinder their practical implementation in biomedical and environmental fields. One significant issue is the scalability of synthesis methods; producing MBenes in large quantities while maintaining high purity and uniformity is often complex and costly. Moreover, the stability of MBenes and their composites under different environmental and biological conditions raises concerns, as they may undergo degradation or lose their functional properties over time, which could limit their long-term effectiveness. Additionally, there is a need for comprehensive toxicity assessments to ensure the safety of MBenes in biomedical applications, particularly when interacting with human tissues or biological systems. This review aims to systematically investigate the environmental and biomedical applications of MBenes and their composites, emphasizing their unique characteristics and potential roles in addressing pressing global challenges. Furthermore, the review will identify and discuss the existing challenges and limitations in the operational performance of MBenes and their composites, providing a critical assessment of their current state in various applications.

This article studies the synthesis, as well as the structural, vibrational, and optical properties of Eu³⁺-doped ZnO quantum dots (QDs) and investigates the energy transfer mechanism from the ZnO host to Eu³⁺ ions using Reisfeld's approximation. Eu³⁺-doped ZnO QDs at varying concentrations (0–7%) were successfully prepared using a wet chemical method. The successful doping of Eu³⁺ ions into the ZnO host lattice, as well as the composition and valence states of the elements present in the sample, were confirmed through X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses. XRD results demonstrated the crystalline nature of the ZnO QDs, revealing their wurtzite (WZ) structure with no secondary phases. XPS analysis provided further confirmation of the presence of Eu³⁺ ions within the ZnO host, with clear signals corresponding to the Zn, O, and Eu elements. The valence states of Eu were verified as trivalent (Eu³⁺), confirming the successful doping of Eu³⁺ ions, as evidenced by the characteristic Eu 3d peaks in the XPS spectra. Raman spectroscopy (RS) was employed to analyze the vibrational modes, revealing shifts in ZnO lattice vibrations due to Eu³⁺ incorporation, indicating strong coupling between Eu³⁺ ions and the ZnO host. Optical properties were studied using UV-Vis absorption, photoluminescence (PL) spectroscopy, and PL decay spectroscopy, showing a significant enhancement of red emission, attributed to the ⁵D₀ → ⁷F₂ transition of Eu³⁺ ions under UV excitation. Using Judd–Ofelt (JO) analysis, the intensity parameters (Ω₂, Ω₄, Ω₆) were derived, providing insights into the asymmetry of the Eu³⁺ ion's local environment and the radiative transition probabilities. Energy transfer processes between the ZnO host and Eu³⁺ dopants were examined, showing efficient sensitization of Eu³⁺ through excitation of the ZnO host, with an optimal Eu³⁺ doping level maximizing luminescence. Eu³⁺-doped ZnO QDs, which emit in the visible light region and are non-toxic, have great potential for applications in photonic devices, light-emitting diodes, and bioimaging.

In this work, we present a comprehensive investigation into the electronic properties and contact behavior of γ-GeSe/Ga₂SSe heterostructures using first-principles calculations. Two stacking configurations, γ-GeSe/SGa₂Se and γ-GeSe/SeGa₂S, are explored, both exhibiting semiconducting behavior with type-II and type-I band alignments, respectively. Notably, our results show that the band alignment transition in these heterostructures can occur spontaneously by simply altering the stacking configuration, eliminating the need for external factors. Additionally, the electronic properties of these heterostructures are highly tunable with an applied electric field, further enabling transitions between type-I and type-II alignments. Specifically, a positive electric field induces a transition from type-II to type-I alignment in the γ-GeSe/SGa₂Se heterostructure, while a negative field drives the reverse transition in the γ-GeSe/SeGa₂S heterostructure. Our findings underscore the potential of γ-GeSe/Ga₂SSe heterostructures for diverse applications, where the tunability of electronic properties is crucial for optimizing device performance.

Gilded wall paintings such as those in Petra-Jordan undergo deterioration processes such as delamination and loss of the gold layer. The aim of this work is to produce a functioning long-lasting adhesive that compensates for binder and gold loss while stabilising the gold layer. Polymer-stabilised gold nanoparticles (AuNPs) as a conservation material for gilded heritage paintings (Nano Gold Gel (NGG)) were synthesised using two facile and affordable synthesis approaches. AuNPs enhance the stability of the adhesive polymer over time and introduce mass conservation to the gold layer. Two natural polymers and one synthetic polymer, frequently used in conservation as adhesives, were used as reducing agents and stabilisers for the nanoparticles. The chemical alteration of the polymers and the Au-polymer interaction at the molecular level were investigated with FTIR spectroscopy, while the chemical environment of gold was investigated with X-ray absorption spectroscopy (XANES/EXAFS). The synthesized NGG was applied on the replica samples to reattach the gold layer to its support. Characterisation results indicate that the formation of AuNPs stabilised by the three polymers did not alter the chemical structure of the polymers. The applied NGG successfully achieved re-adhesion and exhibited appropriate optical and chemical properties for use as a conservation material.

A magnetic-biopolymer composite of carboxymethyl cellulose (CMC), designated as Fe₃O₄@CMC, was synthesized featuring remarkable stability and an active surface with a green biosynthetic method. This composite was engineered to serve as a substrate for stabilizing silver nanoparticles (Ag NPs) with enhanced functional properties. The catalytic efficacy of the nanocatalyst, incorporating Ag NPs at concentrations of 3%, 7%, and 10%, was evaluated for the reduction of the toxic compound 4-nitrophenol to the beneficial 4-aminophenol. Among the tested configurations, the formulation containing 10% silver nanoparticles, in conjunction with Euphorbia plant extract as a bioreducing agent, exhibited the highest reduction efficiency and favorable reaction kinetics, rendering it the optimal choice. The apparent rate constant (K _app) was assessed by fine-tuning the catalyst parameters, while the reaction mechanism was further elucidated by adjusting the concentrations of NaBH₄ and 4-nitrophenol. Notably, the catalyst demonstrated good stability over five consecutive reduction cycles and could be easily retrieved from the reaction mixture using an external magnet.

Carbon dot (CD)-based theranostics offers a promising approach for breast cancer (BC) treatment, integrating ultra-localized chemo-photothermal effects to address chemoresistance and enhance therapeutic control. Herein, the development of a targeted theranostic nanosystem for the chemo-phototherapy of breast cancer is described. Fluorescent and biocompatible CDs were passivated with 1,2-bis(3-aminopropylamino)ethane (bAPAE) and decorated with the targeting agent folic acid (FA) through conjugation with a PEG spacer. This yielded CDs-bAPAE-PEG-FA, hydrophilic nanocarriers (12 nm) with a high drug interaction surface. Fluorescence analysis confirmed their utility as bioimaging probes, while NIR light stimulation demonstrated good photothermal conversion. Doxorubicin-loaded CDs (CDs-bAPAE-PEG-FA/Dox) showed an on-demand NIR-boosted drug release, increased by 50% after localized NIR exposure, while in vitro studies on BC cells MCF-7 and MDA-MB-231 demonstrated NIR-enhanced antitumor efficacy, providing the opportunity to realize selective and remote-controlled synergistic therapy. Furthermore, uptake investigations highlighted the imaging potential of CDs and efficient internalization of doxorubicin, emphasizing FA's role in receptor-mediated specific targeting. Data suggest that CDs-bAPAE-PEG-FA/Dox could perform efficient image-guided and selective BC therapy, enhancing the therapeutic outcomes.

Flexible and wearable devices play a pivotal role in the realm of smart portable electronics due to their diverse applications in healthcare monitoring, soft robotics, human–machine interfaces, and artificial intelligence. Nonetheless, the extensive integration of intelligent wearable sensors into mass production faces challenges within a resource-limited environment, necessitating low-cost manufacturing, high reliability, stability, and multi-functionality. In this study, a cost-effective fiber laser direct writing method (fLDW) was illustrated to create highly responsive and robust flexible sensors. These sensors integrate laser-induced graphene (LiG) with mixed metal oxides on a flexible polyimide film. fLDW simplifies the synthesis of graphene, functionalization of carbon structures into graphene oxides and reduced graphene oxides, and deposition of metal-oxide nanoparticles within a single experimental laser writing setup. The preparation and surface modification of dense oxygenated graphene networks and semiconducting metal oxide nanoparticles (CuO_x, ZnO_x, FeO_x) enables rapid fabrication of LiG/MO_x composite sensors with the ability to detect and differentiate various stimuli, including visible light, UV light, temperature, humidity, and magnetic fluxes. Further, this in situ customizability of fLDW-produced sensors allows for tunable sensitivity, response time, recovery time, and selectivity. The normalized current gain of resistive LiG/MO_x sensors can be controlled between −2.7 to 3.5, with response times ranging from 0.02 to 15 s, and recovery times from 0.04 to 6 s. Furthermore, the programmable properties showed great endurance after 200 days in air and extended bend cycles. Collectively, these LiG/MO_x sensors stand as a testament to the effectiveness of fLDW in economically mass-producing flexible and wearable electronic devices to meet the explicit demands of the Internet of Things.

The interaction of microwave radiation with carbon-based materials induces rapid, instantaneous heating. When combined with the plasma excitation capabilities of microwaves, this property presents novel avenues for synthesizing carbon-based materials that require high temperatures and catalytic activity. This review investigates the response of carbon-based materials to microwave radiation, analyzes the dielectric loss mechanism responsible for heat generation, and details the microwave plasma excitation mechanisms employed in the synthesis and processing of carbon-based materials. Furthermore, the structure of microwave reactors is discussed, followed by a discussion of their diverse applications in both laboratory and industrial settings. Lastly, the review addresses the challenges associated with the practical implementation of microwave technology and explores future development prospects, with a particular focus on the application of microwaves in carbon-based material synthesis.

Metal phosphate-type compounds have been utilized in diverse applications, and their distinctive chemical properties have recently opened avenues for their use as catalysts. Metal phosphates have previously demonstrated significant electrocatalytic activity for the anodic oxygen evolution reaction (OER) in electrochemical water splitting. However, the critical factors influencing OER electrocatalysis on Ni-based phosphates have been insufficiently explored. We herein demonstrate nickel (Ni)-based phosphates—monoclinic Ni₃(PO₄)₂, monoclinic Ni₂P₂O₇, and monoclinic Ni₂P₄O₁₂—as exemplary materials exhibiting outstanding OER activity in alkaline media. These Ni-based phosphates exhibit superior OER overpotentials compared to conventional Ni-based oxides (NiO) and phosphides (Ni₂P). Additionally, their OER-specific activity surpasses that of the rare metal-based benchmark, IrO₂, and previously reported state-of-the-art crystalline electrocatalysts comprising nonprecious metals. Long-term durability tests show that Ni₃(PO₄)₂ maintains its OER activity even after 1000 repeated potential cycles while retaining its elemental composition and Raman spectrum. To understand the excellent OER activities of Ni-based phosphates, the atomic configurations within their crystals are examined. Remarkably, a clear correlation between Ni–O bond length and OER overpotentials is observed in both Ni-based phosphates and NiO, i.e., shorter Ni–O bond lengths are highly beneficial for the OER. Density functional theory (DFT) calculations revealed that the outstanding OER activities of Ni-based phosphates are facilitated by their favorable electronic orbitals, which strengthen the Ni–O bond and improve the adsorption of OER intermediates on Ni sites. This mechanism is substantiated by DFT calculations employing surface slab models, where the adsorption of OER intermediates on the surface of Ni-based phosphates is more energetically favorable than on the surface of NiO. Hence, Ni-based phosphates are promising OER electrocatalysts, and this study provides important guidelines to further improve Ni-based electrocatalysts.