Heterostructured Nanoparticles Research Articles

Bismuth Tungstate-Silver Sulfide Z-Scheme Heterostructure Nanoglue Promotes Wound Healing through Wound Sealing and Bacterial Inactivation.

Rapid wound closure and bacterial inactivation are effective strategies to promote wound healing. Herein, a versatile nanoglue, bismuth tungstate (Bi2WO6)-silver sulfide (Ag2S) direct Z-scheme heterostructure nanoparticles (BWOA NPs), was designed to accelerate wound healing. BWOA NPs' hollow structure and rough surface could effectively close wound tissues acting as a barrier between external bacteria and the wound. More importantly, the unique Z-scheme heterostructure endows BWOA NPs with an effective electron and hole separating ability with potent redox potential, where electrons and holes could effectively react with water and oxygen to produce reactive oxygen species, leading to a higher antibacterial activity against both endogenous and external bacteria at the wound site. A series of in vitro and in vivo biological assessments demonstrated that BWOA NPs could rapidly close wounds and promote wound healing. With sunlight irradiation, the inhibiting rates of BWOA NPs against Escherichia coli and Staphylococcus aureus are 61.62 ± 2.85 and 73.40 ± 3.28%, respectively. Also, the wound healing rate in BWOA NP-treated mice is 25.90 ± 5.85% higher than PBS. This design provides a new effective strategy to promote bacterial inactivation and accelerate wound healing.

Deep Eutectic Solvent-Enabled Plasmonic Nanocellulose Aerogel: On-Demand Three-Dimensional (3D) SERS Hotspot Based on Collapsing Mechanism.

Exceptional surface enhanced Raman scattering (SERS) can be achieved by on-demand mechanisms mediated by the formation of three-dimensional (3D) network supporting hotspots. Herein, a deep eutectic solvent (DES) is used to fabricate plasmonic aerogels as sustainable SERS substrates consisting of different gold nanoparticle (AuNP) heterostructures synthesized in the presence of cellulose nanocrystals (CNCs). This analytical approach is based on the AuNPs 3D arrangement within the CNC matrix, where the transient inter-CNCs interactions collapse after loading with the analyte aqueous solution, forming hotspots on demand. Theoretical calculations support the on-demand SERS mechanism, which consists of the hotspot formation by bringing the AuNPs closer upon activation with the liquid sample loading. To evaluate the plasmonic aerogel performance as a sensing platform, the organophosphorus pesticides edifenphos and parathion were tested in rice and tea extracts. Also, the detection of Methylene Blue in fish muscle extract resulted in a detection limit of 9.8 nM. The results demonstrate that the 3D plasmonic aerogel exhibits significantly higher SERS enhancement and sensitivity when compared to conventional 2D SERS substrates. The use of a green designer solvent, biobased ingredients, and the introduction of on-demand SERS-based sensing pave the way for further developments in the analysis of liquid samples within a sustainable framework.

Oxidation-induced catalytic performance of heterostructured Ni-TiO2 nanoparticles and formation of Leuco-Methylene blue

Oxidation-induced catalytic performance of heterostructured Ni-TiO2 nanoparticles and formation of Leuco-Methylene blue

Multifunctional Ni/NiO heterostructure nanoparticles doped carbon nanorods modified separator for enhancing Li–S battery performance

The shuttle effect caused by soluble polysulfide diffusion and slow redox kinetics seriously hinder the further practical application of Li–S batteries. In order to overcome above problems, herein, we designed a novel carbon nanorods composite doped with Ni/NiO heterostructure nanoparticles (Ni/NiO-C) using a simple and high-yield in-situ technique. On the one hand, abundant heterointerface on the surface of nanoparticles provides a more effective polysulfide anchoring behavior. On the other hand, the electrical conductivity of Ni/NiO promotes rapid reaction kinetics of lithium polysulfides. Therefore, as multifunctional separator modification materials, Ni/NiO-C nanorods effectively regulates the polysulfide reactions from both physical and chemical aspects, and improves the electrochemical performance of the sulfur cathode. As a result, a high reversible capacity of 1462 mAh g−1 (0.2 C) and a low capacity decay rate of ∼0.078% per cycle are obtained. Even at a high sulfur loading of 3.8 mg cm−2, a considerable areal capacity of 4.24 mAh cm−2 can be reached. This work provides a new method for rationally design of separator modification by heterostructure composite for Li–S batteries.

Engineering Heterostructures of Layered Double Hydroxides and Metal Nanoparticles for Plasmon-Enhanced Catalysis

Artificially designed heterostructures formed by close conjunctions of plasmonic metal nanoparticles (PNPs) and non-plasmonic (2D) lamellar nanostructures are receiving extensive interest. The synergistic interactions of the nanounits induce the manifestation of localized surface plasmon resonance (LSPR) in plasmonic metals in the specific environment of the 2D-light absorbing matrix, impacting their potential in plasmon enhanced catalysis. Specifically, layered double hydroxides (LDH) with the advantages of their unique 2D-layered structure, tuned optical absorption, ease of preparation, composition diversity, and high surface area, have emerged as very promising candidates for obtaining versatile and robust catalysts. In this review, we cover the available PNPs/LDH heterostructures, from the most used noble-metals plasmonic of Au and Ag to the novel non-noble-metals plasmonic of Cu and Ni, mainly focusing on their synthesis strategies toward establishing a synergistic response in the coupled nanounits and relevant applications in plasmonic catalysis. First, the structure–properties relationship in LDH, establishing the desirable features of the 2D-layered matrix facilitating photocatalysis, is shortly described. Then, we address the recent research interests toward fabrication strategies for PNPs/support heterostructures as plasmonic catalysts. Next, we highlight the synthesis strategies for available PNPs/LDH heterostructures, how these are entangled with characteristics that enable the manifestation of the plasmon-induced charge separation effect (PICS), co-catalytic effect, or nanoantenna effect in plasmonic catalysis with applications in energy related and environmental photocatalysis. Finally, some perspectives on the challenges and future directions of PNPs/LDHs heterostructures to improve their performance as plasmonic catalysts are discussed.

Bimetallic Zn3Sn2 electrocatalyst derived from mixed oxides enhances formate production towards CO2 electroreduction reaction

As a potential approach to mitigate greenhouse effect meanwhile produce value-added chemical, electrochemical reduction reaction of CO2 (eCO2RR) to formate has gained increasing popularity recently, while its development is impeded by lack of electrocatalyst with satisfying selectivity and activity and low toxicity. Herein, we develop bimetallic Zn3Sn2 catalyst in-situ originated from the hetero-structured ZnxSnyOz nanoparticles supported on CNTs. With an optimized composition, the Zn3Sn2 catalyst (YSn = 39.1 %) achieves higher selectivity for formate by suppressing CO adsorption and reducing the energy barrier of formate intermediate *OCHO compared to its pristine counterparts, which is supported by DFT calculation. It enables a remarkably high Faradic efficiency (FE)formate of 96.7 %, formate yield (924 ppm h−1 mg−1), 26.0 mA cm−2 partial current density of formate (jformate), and better durability in flow cell at −1.1 V vs. reversible hydrogen electrode (RHE), which outperforms most of the reported electrocatalysts for CO2-to-formate conversion. The enhanced formate production from eCO2RR is unlocked for the synergistic effect between Zn-Sn system, implicating vast possibility to improve the electrocatalytic reactivity utilizing metal-metal interaction.

Portable Wireless Intelligent Electrochemical Sensor for the Ultrasensitive Detection of Rutin Using Functionalized Black Phosphorene Nanocomposite.

To build a portable and sensitive method for monitoring the concentration of the flavonoid rutin, a new electrochemical sensing procedure was established. By using nitrogen-doped carbonized polymer dots (N-CPDs) anchoring few-layer black phosphorene (N-CPDs@FLBP) 0D-2D heterostructure and gold nanoparticles (AuNPs) as the modifiers, a carbon ionic liquid electrode and a screen-printed electrode (SPE) were used as the substrate electrodes to construct a conventional electrochemical sensor and a portable wireless intelligent electrochemical sensor, respectively. The electrochemical behavior of rutin on the fabricated electrochemical sensors was explored in detail, with the analytical performances investigated. Due to the electroactive groups of rutin, and the specific π-π stacking and cation–π interaction between the nanocomposite with rutin, the electrochemical responses of rutin were greatly enhanced on the AuNPs/N-CPDs@FLBP-modified electrodes. Under the optimal conditions, ultra-sensitive detection of rutin could be realized on AuNPs/N-CPDs@FLBP/SPE with the detection range of 1.0 nmol L−1 to 220.0 μmol L−1 and the detection limit of 0.33 nmol L−1 (S/N = 3). Finally, two kinds of sensors were applied to test the real samples with satisfactory results.

In-situ construction of nano-sized Ni-NiO-MoO2 heterostructures on holey reduced graphene oxide nanosheets as high-capacity lithium-ion battery anodes

Transition metal oxide anodes for lithium-ion batteries (LIBs) have evoked widespread concern by reason of their high theoretical capacity, abundance, and diversity. Nevertheless, they suffer from severe volume expansion/contraction and slow reaction kinetics during cycling, resulting in poor electrochemical lithium storage performance. Herein, we ingeniously design a unique multi-component composite with Ni-NiO-MoO2 heterostructure nanoparticles in-situ dispersed on holey reduced graphene oxide (rGO) nanosheets using a facile self-sacrificed MOFs template method. The integration of Ni-NiO-MoO2 heterostructure nanoparticles and well-conductive rGO nanosheets with unique nanoholes can collaborate the inherent properties of each component to improve the reaction kinetics and synergistically enhance the lithium storage property. Thereby, the Ni-NiO-MoO2/rGO composite as a LIB anode exhibits outstanding cycling performance with a high reversible capacity (910 mAh g−1 after 220 cycles at 500 mA g−1) as well as excellent rate capability maintaining the great capacity retention of 534 mAh g−1 at 3000 mA g−1. This research offers a vital inspiration for designing and fabricating multi-component metal oxide-based composite anode materials for high-performance LIBs.

Yolk-shell shaped Au-Bi2S3 heterostructure nanoparticles for controlled drug release and combined tumor therapy

To fabricate a novel stimuli-responsive system enabling controlled drug release and synergistic therapy, yolk-shell shaped bismuth sulfide modified with Au nanoparticles (Au-Bi2S3) was prepared. The Au-Bi2S3 nanomaterial with heterojunction structure exhibited excellent photothermal conversion efficiency and considerable free radicals yield under laser irradiation. The drug delivery capacity was confirmed by co-loading Berberine hydrochloride (BBR) and a phase change material 1-tetradecanol (PCM), which could be responsible for NIR light induced thermal controlled drug release. In vitro investigation demonstrated that Au-Bi2S3 has cell selectivity, and with the assistance of the properties of Au-Bi2S3, the loaded drug could give full play to their cancer cell inhibition ability. Our work highlights the great potential of this nanoplatform which could deliver and control Berberine hydrochloride release as well as realize the synergistic anti-tumor strategy of photothermal therapy, photodynamic therapy and chemotherapy for tumor therapy.

Exsolution of phase-separated nanoparticles via trigger effect toward reversible solid oxide cell

The electrocatalytic characteristics of heterostructure nanoparticles have attracted attention for use in devices addressing energy and environmental issues. Among the various features, exsolved alloy or core–shell nanoparticles display high reactive surface area and strong interaction between the metal and substrate oxide. Herein, we report multifunctional heterostructure nanoparticles, namely Fe/Cu Janus nanoparticles (JN) and verify an exsolution trigger effect using Cu as a seed in the La0.43Sr0.37Fe0.09Cu0.03Ti0.88O3-δ (Fe75) perovskite substrate. During the exsolution process, the exsolved Cu particles played a key role in triggering the Fe exsolution by contributing additional surface energy. These Fe/Cu JNs exhibited outstanding catalytic activity in a reversible solid oxide cell fed with H2O/H2 and CO/CO2 fuels. A single cell with Fe75 showed an impressive current density of − 1.11 A cm−2 at 1.3 V and 900 °C. Our study experimentally elucidated the mechanism of the triggering of co-exsolution and demonstrated a multifunctional catalyst using Fe/Cu JNs.

Expanded Tunability of Intraparticle Frameworks in Spherical Heterostructured Nanoparticles through Substoichiometric Partial Cation Exchange.

Partial cation exchange reactions provide a synthetic pathway for rationally constructing heterostructured nanoparticles that incorporate different materials at precise locations. Multiple sequential partial cation exchange reactions can produce libraries of exceptionally complex heterostructured nanoparticles, but the first partial exchange reaction is responsible for defining the intraparticle frameworks that persist throughout and help to direct subsequent exchanges. Here, we studied the partial cation exchange behavior of spherical nanoparticles of roxbyite copper sulfide, Cu1.8S, with substoichiometric amounts of Zn2+. We observed the formation of ZnS-Cu1.8S-ZnS sandwich spheres, which are already well known in this system, as well as ZnS-Cu1.8S Janus spheres and Cu1.8S-ZnS-Cu1.8S central band spheres, which have not been observed previously as significant subpopulations of samples. Aliquots taken during the formation of the heterostructured nanoparticles suggest that substoichiometric amounts of Zn2+ limit the number of sites per particle where exchange initiates and/or propagates, thereby helping to define intraparticle frameworks that are different from those observed using excess amounts of exchanging cations. We applied these insights from mixed-population samples to the higher-yield synthesis of ZnS-Cu1.8S Janus spheres, as well as the higher-order derivatives ZnS-(CdS-Cu1.8S), ZnS-(CdS-ZnS), and ZnS-(CdS-CoS), which have unique features relative to previously reported analogues. These results demonstrate how the diversity of intraparticle frameworks in spherical nanoparticles can be expanded to produce a broader range of downstream heterostructured products.

Bimetallic Exsolved Heterostructures of Controlled Composition with Tunable Catalytic Properties.

In this paper, we show how the composition of bimetallic Fe-Ni exsolution can be controlled by the nature and concentration of oxygen vacancies in the parental matrix and how this is used to modify the performance of CO2-assisted ethane conversion. Mesoporous A-site-deficient La0.4Sr0.6-αTi0.6Fe0.35Ni0.05O3±δ (0 ≤ α ≤ 0.2) perovskites with substantial specific surface area (>40 m2/g) enabled fast exsolution kinetics (T < 500 °C, t < 1 h) of bimetallic Fe-Ni nanoparticles of increasing size (3-10 nm). Through the application of a multitechnique approach we found that the A-site deficiency determined the concentration of oxygen vacancies associated with iron, which controlled the Fe reduction. Instead of homogeneous bimetallic nanoparticles, the increasing Fe fraction from 37 to 57% led to the emergence of bimodal Fe/Ni3Fe systems. Catalytic tests showed superior stability of our catalysts with respect to commercial Ni/Al2O3. Ethane reforming was found to be the favored pathway, but an increase in selectivity toward ethane dehydrogenation occurred for the systems with a low metallic Fe fraction. The chance to control the reduction and growth processes of bimetallic exsolution offers interesting prospects for the design of advanced catalysts based on bimodal nanoparticle heterostructures.

Optical and Electrochemical Study on the Performance of Au@TiO2 core-shell Heterostructured Nanoparticles as Photocatalyst for Photodegradation of Methylene Blue under Solar-light Irradiation

Optical and Electrochemical Study on the Performance of Au@TiO2 core-shell Heterostructured Nanoparticles as Photocatalyst for Photodegradation of Methylene Blue under Solar-light Irradiation

ROS-responsive Ag-TiO2 hybrid nanorods for enhanced photodynamic therapy of breast cancer and antimicrobial applications

There has been significant interest in designing heterostructured nanoparticles with excellent synergistic properties and multifunctionality. Herein, this work reports on the design of reactive oxygen species- (ROS-) responsive Ag decorated TiO2 hybrid nanorods (HNRs) with dual functionalities of enhanced photodynamic therapy and antibacterial activity. A de-wetting phenomenon was employed to nucleate and crystallize Ag nanoparticles onto the surface of TiO2 nanorods resulting in Ag-TiO2 hybrid nanocomposites. The use of the Pluronic® F-127 polymer, which is permitted by the Food and Drug Administration (FDA), remarkably improved the biocompatibility of Ag-TiO2 HNRs tested in 4T1 breast cancer cells. Furthermore, Ag-TiO2 HNRs endocytosed by cancer cells produced high intracellular ROS under UV conditions (5.6 mW cm−2), resulting in cancer cell apoptosis. Similarly, the distinctive features of Ag NPs on TiO2 nanorods slow down the recombination rate of electrons–holes, and exhibited 90% killing efficacy against Escherichia coli (gram-negative/rods) and Staphylococcus aureus (gram-positive/cocci). The potential of photo-activated Ag-TiO2 HNRs, as demonstrated in this work, indicates that this heterostructured material is a promising novel dual-therapeutic strategy against cancer cells and microbial agents.

Molecular Dynamics Beyond the Monolayer Adsorption as Derived from Langmuir Curve Fitting.

Langmuir adsorption model is a classic physical-chemical adsorption model and is widely used to describe the monolayer adsorption behavior at the material interface in environmental chemistry. Traditional adsorption dynamic modeling solely considered the surface physiochemical interaction between the adsorbent and adsorbate. The surface reaction dynamics resulting from the heterogeneous surface and intrinsic electronic structure of absorbents were rarely considered within the reported adsorption experiments. Herein, by employing the chlorine hybrid graphene oxide (GO-Cl) to adsorb Ag+ in an aqueous solution, complicated molecular dynamics significantly deviated from the monolayer adsorption mechanism, as suggested by Langmuir adsorption curve fitting, has been elucidated down to atomic scale. In the time-dependent Ag adsorption experiments, both Ag single atoms and Ag/AgCl nanoparticle heterostructures are observed to be formed sequentially on GO-Cl. These observations indicate that for the surface adsorption dynamics, not only the surface chemical adsorption process involved but also photoreduction and the C-Cl bond cleavage reaction has been heavily engaged within the GO-Cl interface, suggesting a much more complicated vision rather than the monolayered adsorption algorithm as derived from curve fitting. This study uses GO-Cl as a simple example to disclose the complicated adsorption dynamic process underneath Langmuir adsorption curve fitting. It advocates the necessity of imaging the interfacial atomic-scale dynamic structure with high-resolution microscopy techniques in modern adsorption studies, rather than simply explaining the adsorption dynamics relying on the curve fitting results due to the complicated physiochemical reactivity of the adsorbents.

Revealing the Origin of Low-Temperature Activity of Ni-Rh Nanostructures during CO Oxidation Reaction with Operando TEM.

In bimetallic heterostructured nanoparticles (NPs), the synergistic effect between their different metallic components leads to higher catalytic activity compared to the activity of the individual components. However, how the dynamic changes through which these NPs adopt catalytically active structures during a reaction and how the restructuring affects their activity are largely unknown. Here, using operando transmission electron microscopy, structural changes are studied in bimetallic Ni–Rh NPs, comprising of a Ni core whose surface is decorated with smaller Rh NPs, during a CO oxidation reaction. The direct atomic‐scale imaging reveals that, under O2‐rich conditions, Ni core partially transforms into NiO, forming a (Ni+NiO)–Rh hollow nanocatalyst with high catalytic activity. Under O2‐poor conditions, Rh NPs alloy with the surface of the core to form a NiRh‐alloy surface, and the NPs display significantly lower activity. The theoretical calculations indicate that NiO component that forms only under O2‐rich conditions enhances the activity by preventing the CO poisoning of the nanocatalysts. The results demonstrate that visualizing the structural changes during reactions is indispensable in identifying the origin of catalytic activity. These insights into the dynamic restructuring of NP catalysts under a reactive environment are critical for the rational design of high‐performance nanocatalysts.

Temperature-controlled synthesis of heterostructured Ru-Ru2P nanoparticles embedded in carbon nanofibers for highly efficient hydrogen production

Developing highly efficient, cost-effective, and stable electrocatalysts for hydrogen evolution reaction (HER) is of considerable importance but remains challenging. Herein, we report the fabrication of a robust Ru-based electrocatalyst, which comprises heterostructured Ru-Ru2P nanoparticles that are embedded in the N,P-codoped carbon nanofibers (CNFs), through a synthetic strategy involving electrospinning and temperature-controlled pyrolysis treatment. The as-prepared Ru-Ru2P catalyst (Ru-Ru2P@CNFs) shows excellent HER catalytic activities with low overpotentials of 11 and 14 mV in acidic and alkaline media, respectively, to achieve a current density of 10 mA cm−2, which are superior to the individual components of pure Ru and Ru2P catalysts. Density functional theory calculations demonstrate the existence of electronic coupling effect between Ru and Ru2P at the heterointerfaces, leading to a well-modulated electronic structure with optimized hydrogen adsorption strength and enhanced electrical conductivity for efficient HER electrocatalysis. In addition, the overall synthetic strategy can be generalized for the synthesis of a series of transitional metal phosphide-based nanofibers, thereby holding a remarkable capacity for various potential applications.

G-C3N4 nanosheets functionalized yttrium-doped ZrO2 nanoparticles for efficient photocatalytic Cr(VI) reduction and energy storage applications

Novel g-C3N4 functionalized yttrium-doped ZrO2 hybrid heterostructured (g-YZr) nanoparticles have been synthesized to investigate photocatalytic Cr(VI) reduction as well as electrochemical energy storage applications. The nanoparticles have been characterized to examine their structural, optical, and photocatalytic properties. XRD confirmed the incorporation of dopant ions and heterostructure development between g-C3N4 and doped ZrO2. When g-C3N4 was doped with ZrO2, the ability of light adsorption was greatly enhanced due to the narrow band gap. The distinctive structure of g-YZr exhibited outstanding photocatalytic Cr(VI) reduction owing to its superior surface area, which greatly prevented the charge carriers' recombination rate and exhibited superior photocatalytic performance within 90 min of solar light irradiation. Furthermore, these catalysts demonstrated similar catalytic Cr(VI) reduction activity following four repeatability tests, indicating the exceptional structural stability of g-YZr catalysts. The electrochemical performance of the electrodes revealed that g-YZr exhibited superior specific capacitance over the other electrodes owing to extra energetic sites and robust synergic effect. Enhanced specific capacitance and long cyclic stability of the hybrid heterostructures displayed their usefulness for energy storage applications.

Printed Chalcogenide/Metal Heterostructured Photodetectors for Flexible Near‐Infrared Sensing

AbstractNear‐infrared (NIR) photodetectors can be fabricated for various applications, such as imaging, military tracking, and medical diagnosis. However, achieving miniaturization and high responsivity for NIR photodetector arrays is still a challenge. In this study, a high‐density NIR photodetector array with a micro/nano chalcogenide and silver nanoparticle heterostructure is achieved using a low‐cost printing strategy. The Ag/Ge2Sb2Te5(GST)/Ag heterostructure is fabricated using a template‐assisted sequential printing strategy. At an absorption wavelength of λ = 980 nm, the NIR photodetector has a high light responsivity of 6.7 × 104 A W−1 owing to the high crystallinity of the GST microwire and refined GST/Ag heterointerface during the printing process. In addition, the sensing pixel interval can be reduced to 25 µm, corresponding to the highest resolution of NIR photodetectors achieved thus far (resolution: 1.0 × 103 dpi). In addition, the NIR photodetector printed on soft substrates exhibits flexibility. Thus, a simple and effective strategy for the fabrication of NIR photodetectors is demonstrated, and precise flexible infrared sensing is achieved.

Covalent organic framework-gold nanoparticle heterostructures amplified dynamic light scattering immunosensor for ultrasensitive detection of NT-proBNP in whole blood

Immunoassay has shown great potential in the detection of various disease protein biomarkers because of its high specificity. However, the sensitivity of conventional immunoassay is relatively limited due to its insufficient colorimetric signal transduction. Herein, we report a novel dynamic light scattering (DLS) immunosensing strategy for ultrasensitive detection of protein markers based on the covalent organic framework-gold nanoparticle (COF@AuNP) heterostructures combined with the gold growth. By taking advantage of the unique acid response characteristics of imine-linked COF, the COF@AuNP is designed as a signal amplifier to boost the release of AuNPs, and then the released AuNPs are enlarged by gold growth to amplify the DLS signal transduction and thus remarkably improve the sensitivity. Combined with the double antibody sandwich magnetic immunoassay, the COF@AuNP-amplified DLS immunosensor successfully achieve the highly sensitive quantitative detection of N-terminal brain-type natriuretic peptide. The limit of detection reaches up to 14 fg mL−1 with the total assay time less than 2 h. The linear detection range was from 0.32 to 1000 pg mL−1, and the coefficient of variation was below 12.5%. Briefly, this immunosensor is demonstrated with high selectivity, accuracy, reproducibility, and reliability in spiked and actual whole blood samples. The COF@AuNP-amplified DLS immunosensing strategy holds high promise as an alternative for detecting disease biomarkers.