Urchin-like Nanostructures Research Articles

Enhanced photoelectrochemical water splitting by a 3D hierarchical sea urchin-like structure: ZnO nanorod arrays on TiO2 hollow hemisphere

A hierarchical sea urchin-like hybrid metal oxide nanostructure of ZnO nanorods deposited on TiO2 porous hollow hemispheres with a thin zinc titanate interface layer is specifically designed and synthesized to form a combined type I straddling and type II staggered junctions. The HHSs, synthesized by electrospinning, facilitate light trapping and scattering. The ZnO nanorods offer a large surface area for improved surface oxidation kinetics. The interface layer of zinc titanate (ZnTiO3) between the TiO2 HHSs and ZnO nanorods regulates the charge separation in a closely coupled hierarchy structure of ZnO/ZnTiO3/TiO2. The synergistic effects of the improved light trapping, charge separation, and fast surface reaction kinetics result in a superior photoconversion efficiency of 1.07% for the photoelectrochemical water splitting with an outstanding photocurrent density of 2.8 mA cm−2 at 1.23 V versus RHE.

Endowing polymeric carbon nitride photocatalyst with CO2 activation sites by anchoring atomic cobalt cluster

Photocatalytic CO2 reduction to high value-added fuels and chemicals is a promising strategy for alleviating both energy and environmental crises. However, the poor CO2 adsorption and activation ability seriously restrict the CO2 photoreduction activity of metal-free carbon nitride (C3N4), which is an emerging material for photocatalysis applications. In this paper, cobalt (Co) atomic clusters were modified on the surface of hierarchical urchin-like hollow C3N4 nanotubes by NaBH4 reduction, which endowed the as-designed Co atomic cluster-anchored and B-doped C3N4 (Co@B-HCN) catalyst with strong CO2 activation and CO2 photoreduction ability. Theoretical calculations and in situ characterization confirmed that the Co atomic clusters anchoring enabled the change in the bond length/angle of adsorbed CO2 molecules, as well as the change from a linear model to a bending model. This could enhance the CO2 adsorption and activation, which played a vital role in reducing the energy barrier of CO2-to-CO reaction. In addition, the construction of the hierarchical urchin-like nanostructure, the anchoring of Co atomic clusters, and the doping of B favored the surface adsorption and charge separation. Attributed to the above merits, the CO yield of Co@B-HCN photocatalyst reaches 157.51 μmol⋅g−1⋅h−1, which is approximately 22 times that of bulk C3N4. This work provides an insight for the surface engineering of C3N4 photocatalysts to realize high-performance photocatalytic CO2 reduction.

Special atmosphere annealed Co3O4 bifunctional catalysts with oxygen defects for high-efficient water splitting

Electrochemical water splitting is widely recognized as an economical and sustainable method for producing high-purity hydrogen using renewable energy sources. Herein, we prepared 3D urchin-like sphere structures of Co3O4 to serve as an excellent bifunctional catalyst for overall water splitting. Different Co3O4 samples were directly synthesized on Ni foam through hydrothermal and annealing processes under various atmospheric conditions, leading to the formation of oxygen vacancies with varying concentrations. Specifically, the Co3O4/NF-Ar/O2 demonstrates outstanding catalytic performance for both OER (η20 = 269 mV) and HER (η10 = 135 mV), while maintaining excellent durability in 1 M KOH. Electrolysis cells employing Co3O4/NF-Ar/O2 as both anode and cathode demonstrate a low cell voltage of 1.56 V to achieve 10 mV cm−2 in alkaline conditions. The excellent catalytic performance can be mainly attributed to the urchin-like nanostructure and the appropriate concentration of oxygen vacancies. This research provides further insights into the application of the method to induce oxygen vacancies in low-cost and high-efficiency transition metal oxides (TMOs)-based catalysts for electrochemical reaction.

G-C3N4 quantum dots decorated on urchin-like TiO2 nanostructures for the photoelectrochemical water splitting

g-C3N4 quantum dots decorated on urchin-like TiO2 nanostructures for the photoelectrochemical water splitting

Urchin-like Fe3O4@Bi2S3 Nanospheres Enable the Destruction of Biofilm and Efficiently Antibacterial Activities.

Biofilm-associated infections (BAIs) have been considered a major threat to public health, which induce persistent infections and serious complications. The poor penetration of antibacterial agents in biofilm significantly limits the efficiency of combating BAIs. Magnetic urchin-like core-shell nanospheres of Fe3O4@Bi2S3 were developed for physically destructing biofilm and inducing bacterial eradication via reactive oxygen species (ROS) generation and innate immunity regulation. The urchin-like magnetic nanospheres with sharp edges of Fe3O4@Bi2S3 exhibited propeller-like rotation to physically destroy biofilm under a rotating magnetic field (RMF). The mild magnetic hyperthermia improved the generation of ROS and enhanced bacterial eradication. Significantly, the urchin-like nanostructure and generated ROS could stimulate macrophage polarization toward the M1 phenotype, which could eradicate the persistent bacteria with a metabolic inactivity state through phagocytosis, thereby promoting the recovery of implant infection and inhibiting recurrence. Thus, the design of magnetic-driven sharp-shaped nanostructures of Fe3O4@Bi2S3 provided enormous potential in combating biofilm infections.

Self-supported urchin-like NiCoPt/nickel foam as an efficient electrocatalyst for hydrogen evolution reaction in alkaline media

Pt/C with low overpotential, good kinetics and long-term stability, is benchmark catalyst for hydrogen evolution reaction (HER). However, high cost and low catalytic activity under alkaline media limit its industry application. Pt alloy with low Pt content is an effective solution to enhance catalytic efficiency and minimize Pt usage. Herein, NiCoPt with urchin-like nanostructure were prepared on self-supported nickel foam and applied as HER catalyst. Based on synergistic effect of transition elements, NiCoPt/NF shows excellent HER performance with overpotentials of 8 mV @10 mA cm−2 in alkaline medium. 12 wt% Pt concentration in NiCoPt/NF is only half of commercial Pt/C.

A disposable sensor based on one-pot synthesized tungsten oxide nanostructure-modified screen printed electrodes for selective detection of dopamine and uric acid.

Here, screen-printed carbon electrodes (SPCEs) were modified with ultrafine and mainly mono-disperse sea urchin-like tungsten oxide (SUWO3) nanostructures synthesized by a simple one-pot hydrothermal method for non-enzymatic detection of dopamine (DA) and uric acid (UA) in synthetic urine. Sea urchin-like nanostructures were clearly observed in scanning electron microscope images and WO3 composition was confirmed with XRD, Raman,FTIR and UV-Vis spectrophotometer. Modification of SPCEs with SUWO3 nanostructures via the drop-casting method clearly reduced the Rct value of the electrodes, lowered the ∆Ep and enhanced the DA oxidation current due to high electrocatalytic activity. As a result, SUWO3/SPCEs enabled highly sensitive non-enzymatic detection of DA (LOD: 51.4nM and sensitivity: 127µAmM-1cm-2) and UA (LOD: 253nM and sensitivity: 55.9µAmM-1cm-2) at low concentration. Lastly, SUWO3/SPCEs were tested with synthetic urine, in which acceptable recoveries for both molecules (94.02-105.8%) were obtained. Given the high selectivity, the sensor has the potential to be used for highly sensitive simultaneous detection of DA and UA in real biological samples.

TMB+-mediated etching of urchin-like gold nanostructures for colorimetric sensing

The morphology-dependent localized surface plasmon resonance of gold nanostructures has been widely utilized for designing sensors. One method relies on the color change of gold nanoparticles upon etching. In previous work, TMB2+ oxidized from 3,3′,5,5′-tetramethylbenzidine (TMB) was found to etch gold nanorods (AuNRs), leading to a spectrum of different colors. However, the preparation of TMB2+ needs the addition of a strong acid and other harsh conditions. Herein, a new colorimetric biosensing platform was developed using urchin-like gold nanoparticles (AuNUs). Compared with AuNRs, the etching of AuNUs can happen under mild conditions by TMB+ at pH 6, protecting enzymes and proteins from denaturation. The role of CTAB surfactant was dissected, and its bromide ions were found to be involved in the etching process. Based on these observations, a one-step colorimetric detection of H2O2 was realized by using horseradish peroxidase and H2O2 to oxidize TMB. Within 30 min, this system achieved a detection limit of 80 nM H2O2. This work offered fundamental insights into the etching of anisotropic gold nanostructures and optimized the etching conditions. These advancements hold promise for broader applications in biosensing and analytical chemistry.

Preparation and SERS applications of Ta2O5 composite nanostructures.

Noble metal and semiconductor composite substrates possess high sensitivity, excellent stability, good biocompatibility, and selective enhancement, making them an important research direction in the field of surface-enhanced Raman scattering (SERS). Ta2O5, as a semiconductor material with high thermal stability, corrosion resistance, outstanding optical properties, and catalytic performance, has great potential in SERS research. This study aims to design and fabricate a composite SERS substrate based on Ta2O5 nanostructures, achieving optimal detection performance by combining the urchin-like structure of Ta2O5 with silver nanoparticles (Ag NPs). The urchin-like Ta2O5 nanostructures were prepared using a hydrothermal reaction method. The bandgap was modulated through structure design and the self-doping technique, the charge transfer efficiency and surface plasmon resonance effects were improved, thereby achieving better SERS performance. The composite substrate enables highly sensitive quantitative detection. This composite SERS substrate combines the electromagnetic enhancement mechanism (EM) and chemical enhancement mechanism (CM), achieving ultra-low detection limits of 10-13 M for R6G. Within the concentration range above 10-12 M, there is a good linear relationship between concentration and peak intensity, demonstrating excellent quantitative analysis capabilities. Furthermore, this composite SERS substrate is capable of precise detection of analytes such as crystal violet (CV) and methylene blue (MB), holding broad application prospects in areas such as food safety and environmental monitoring.

Hairpin cascade circuits on programmable DNA-nucleated spherical nucleic acid for intracellular targeted microRNA imaging

DNA molecular probes have been increasingly used for biological imaging and tumor theranostics. In particular, live-cell imaging of low abundance microRNA (miRNA) with high accuracy and efficiency was extremely important for understanding functions and dynamics of miRNA. Herein, an easy-to-obtain DNA-nucleated spherical nucleic acid (DSNA) was constructed by one pair of hairpin probes “sticked” on self-assembled three-dimensional (3D) urchin-like DNA nanostructures (UDNs) to realize sensitive imaging of tumor-related miRNA in living cells. UDNs were prepared through four short single-stranded DNA by a simple “one-pot” annealing process that took only a few minutes. Moreover, sticking the reactants of hairpin probes on the UDNs not only sped up the reaction kinetic rate, but also improved the sensitivity and efficiency of miRNA-triggered hairpin cascade circuits. Compared with traditional AuNP-based spherical nucleic acid, the DSNA possessed superb biocompatibility and stability, excellent cell internalization capability and accessibility, which endowed them tremendous advantages for the monitoring of miRNA in living cells. Therefore, our developed strategy exhibited great potential in sensitive imaging of intracellular miRNA, offering a new avenue for early tumor diagnosis and related biomedical research.

Bioinspired urchin-like murray carbon nanostructure with protection shell for advanced lithium-sulfur batteries

Commercial application of lithium-sulfur (Li-S) batteries is hindered by the insulating nature of sulfur and the dissolution of polysulfides. Here, a bioinspired 3D urchin-like N-doped Murray’s carbon nanostructure (N-MCN) with interconnected micro-meso-macroporous structure and a polydopamine protection shell has been designed as an effective sulfur host for high-performance Li-S batteries. The advanced 3D hierarchically porous framework with the characteristics of the generalized Murray’s law largely improves electrolyte diffusion, facilitates electrons/ions transfer and provides strong chemisorption for active species, leading to the synergistic structural and chemical confinement of polysulfides. As a result, the obtained P@S/N-MCN electrode with high areal sulfur loading demonstrates high capacity at high current densities after long cycles. This work reveals that following the generalized Murray’s law is feasible to design high-performance sulfur cathode materials for potentially practical Li-S battery applications.

Highly Sensitive and Selective Electrochemical Detection of Dopamine and Uric Acid Using Sea Urchin-like Tungsten Oxide Nanostructure Modified SPCE

Highly Sensitive and Selective Electrochemical Detection of Dopamine and Uric Acid Using Sea Urchin-like Tungsten Oxide Nanostructure Modified SPCE

ReS2@Au NPs as signal labels quenching steady photocurrent generated by NiCo2O4/CdIn2S4/In2S3 heterojunction for sensitive detection of CYFRA 21-1

In order to achieve rapid and sensitive detection of CYFRA 21-1, a signal-off photoelectrochemical (PEC) immunosensor was devised with NiCo2O4/CdIn2S4/In2S3 heterojunction photoactive materials as sensing platform and ReS2@Au NPs as the secondary antibody labels amplifying signal based on the energy band-matching cascade structure and double suppression effect. NiCo2O4 possessed a faster charge transfer rate due to the abundance of redox electron pairs (Co3+/Co2+ and Ni3+/Ni2+). To further improve the PEC properties of NiCo2O4 under visible light, CdIn2S4 with matching bandgap energy was selected to form heterojunction with NiCo2O4 and sensitized with In2S3. The proposed heterojunctions with well-matched band structure promoted the transfer of photo-generated carriers and were exploited as signal transducers for immobilization of antibodies and recognition of CYFRA 21-1. Furthermore, a novel urchin-like p-type ReS2 semiconductor nanostructure functionalized by Au NPs was firstly used as a nanolabel to quench the signal. On the one hand, the Schottky heterojunction generated by ReS2 and Au NPs could compete with the transducer substrate for both light and electron donors. On the other hand, the large space steric hindrance of ReS2 prevented contact between the matrix and AA. Subsequently, the sensor was sensitive in a wide range of concentrations for CYFRA 21-1 (0.0001–50 ng/mL), and the detection limit was 0.05 pg/mL.

Engineering of Nanostructured WO3 Powders for Asymmetric Supercapacitors

Transition metal oxide nanostructures are promising materials for energy storage devices, exploiting electrochemical reactions at nanometer solid-liquid interface. Herein, WO3 nanorods and hierarchical urchin-like nanostructures were obtained by hydrothermal method and calcination processes. The morphology and crystal phase of WO3 nanostructures were investigated by scanning and transmission electron microscopy (SEM and TEM) and X-ray diffraction (XRD), while energy storage performances of WO3 nanostructures-based electrodes were evaluated by cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) tests. Promising values of specific capacitance (632 F/g at 5 mV/s and 466 F/g at 0.5 A/g) are obtained when pure hexagonal crystal phase WO3 hierarchical urchin-like nanostructures are used. A detailed modeling is given of surface and diffusion-controlled mechanisms in the energy storage process. An asymmetric supercapacitor has also been realized by using WO3 urchin-like nanostructures and a graphene paper electrode, revealing the highest energy density (90 W × h/kg) at a power density of 90 W × kg-1 and the highest power density (9000 W/kg) at an energy density of 18 W × h/kg. The presented correlation among physical features and electrochemical performances of WO3 nanostructures provides a solid base for further developing energy storage devices based on transition metal oxides.

Simple one-step synthesis of urchin-like Fe–Mn nanostructures via statistical design and their effects on the morphology

In the current investigation, a new urchin-like nanostructure using an authorized one-pot precipitation technique was synthesized using Taguchi statistical design. The effect of factors, including the concentration of FeSO4⋅7H2O, KMnO4, NaOH, and reaction temperature, on the diameter-to-length ratio of the nanoneedles and the regularity or irregularity morphology of other samples, was investigated. KMnO4 and FeSO4⋅7H2O, with a contribution of 32.62% and 30.9%, had the most substantial effect on the nanoneedles' diameter. The surface morphology and chemical composition of the as-prepared samples were studied using field emission scanning electron microscopy, X-ray diffraction, and energy dispersive spectroscopy (EDX) analyses. The length and needle diameter was obtained 140 and 17 nm, respectively. The result of BET analysis for the highest and the lowest value of D/L shows that the smallest ratio of diameter to length has a high specific surface area. The results show that sample S4 has a particular surface area of 74 m2/g, much more than S3 (25 m2/g). The estimated crystallite size in synthesized S3 and S4 samples are 41.64 and 26.49 nm, respectively.

Urchin-like Bi2S3 nanostructures with rich sulfur vacancies for ppb-level NO2 sensing

The unique features of Bi2S3 enable it to be a promising candidate for preparing high-performance NO2 gas sensors. However, pristine Bi2S3 is usually inert for effective detection of ppb-level NO2 at room temperature owing to the lack of active sites. Herein, urchin-like Bi2S3 nanostructures with rich-defects were designed and prepared by a one-step hydrothermal method to realize ppb-level NO2 detection at room temperature. The optimal sensor based on urchin-like Bi2S3 with sulfur defects demonstrated an ultrahigh sensing response of 21.7 (almost 13 times higher than that of pristine Bi2S3) and a short response/recovery time of 42/36 s to 1 ppm NO2. In addition, an ultralow theoretical detection limit of 3 ppb was achieved for the sensor. The improved sensing performance could be ascribed to the numerous sulfur vacancies and the distinctive hierarchical structures, which promote the adsorption of NO2 molecules and boost charge transfer between NO2 and Bi2S3. This study would provide a new perspective on nanostructured materials for NO2 sensing at room temperature.

Singlet oxygen-dominated activation of peroxymonosulfate by 3D hierarchical MnO2 nanostructures for degradation of organic pollutants in water: Surface defect and catalytic mechanism

Manganese dioxide (MnO2) is attracting significant attention in the activation of persulfate for the degradation of organic pollutants in water. But the factor determining the catalytic efficiency of MnO2, and the evolution of reactive oxygen species (ROS) remain equivocal and elusive. Herein, three-dimensional (3D) hierarchical MnO2 nanostructures are synthesized via the calcination of hydrothermal product and used to active peroxymonosulfate (PMS) for degradation of acid orange 7 (AO7) in water. The results show that the calcination temperature can tune the morphology of 3D hierarchical MnO2 nanostructures from flower to urchin-like as well as phase transformation from δ-MnO2 to α-MnO2. Owing to the presence of more surface defects and surface adsorbed oxygen species, the urchin-like α-MnO2 nanostructures prepared at 500 °C (MnO2-500) deliver the best catalytic activity in activation of PMS, and 98.3 % of AO7 is degraded in 300 s. Additionally, the MnO2-500 shows wide pH applicability (3.5–9.6). Quenching tests and electron paramagnetic resonance spectra reveal that the catalytic oxidation of AO7 in the MnO2-500/PMS system is mainly mediated by the non-radical pathway, and the dominated ROS is 1O2. Besides, electrochemical experiment confirms the presence of electron transfer in the catalytic process. Density functional theory calculations indicate that the CN and CS groups of AO7 with high electron density are easily attacked by electrophilic ROS, which is further confirmed by liquid chromatography-mass spectrometry. Finally, MnO2-500 exhibits gradually enhanced catalytic activity with the increased cycle number due to the increased surface defects and the surface adsorbed oxygen. This study provides new insight into the PMS activation by MnO2-based catalyst for the remediation of organic pollutants in water.

Progress in Preparation of Sea Urchin-like Micro-/Nanoparticles.

Urchin-like microparticles/nanoparticles assembled from radial nanorods have a good appearance and high specific surface area, providing more exposed active sites and shortening the diffusion path of photoexcited carriers from the interior to the surface. The interfacial interaction and physical and chemical properties of the materials can be improved by the interfacial porous network induced by interlacing nano-branches. In addition, multiple reflections of the layered microstructure can absorb more incident light and improve the photocatalytic performance. Therefore, the synthesis and functionalization of three-dimensional urchin-like nanostructures with controllable size, shape, and hierarchy have attracted extensive attention. This review aims to provide an overview to summarize the structures, mechanism, and application of urchin-like microparticles/nanoparticles derived from diverse synthesis methods and decoration types. Firstly, the synthesis methods of solid urchin-like micro-/nanoparticles are listed, with emphasis on the hydrothermal/solvothermal method and the reaction mechanism of several typical examples. Subsequently, the preparation method of composite urchin-like micro-/nanoparticles is described from the perspective of coating and doping. Then, the research progress of urchin-like hollow microspheres is reviewed from the perspective of the step-by-step method and synchronous method, and the formation mechanism of forming urchin-like hollow microspheres is discussed. Finally, the application progress of sea urchin-like particles in the fields of photocatalysis, electrochemistry, electromagnetic wave absorption, electrorheological, and gas sensors is summarized.

Pt deposited on sea urchin-like CuCo2O4 nanowires: Preparation, the excellent peroxidase-like activity and the colorimetric detection of sulfide ions

Detecting of sulfur ions (S2-) in environment is critical to human health. In this work, a fast and convenient colorimetric sensing platform for S2- was developed. In detail, Pt deposited on sea urchin-like CuCo2O4 nanostructures (Pt/CuCo2O4) was synthesized and demonstrated to possess enhanced peroxidase-like performance, similar to the natural horseradish peroxidase (HRP). Pt/CuCo2O4 can catalyze colorless 3, 3, 5, 5-Tetramethylbenzidine (TMB) to be oxidized by H2O2 into a blue product (oxTMB). When the above system encounters sulfur ions (S2-), the peroxidase-like activity of Pt/CuCo2O4 is inhibited, accompanied with the color change of reaction solutions. On this basis, a colorimetric sensing platform for S2- can be established. Kinetic experiments verified Pt/CuCo2O4 possessed a higher affinity with substrate than that of HPR. The excellent peroxidase-like performance of Pt/CuCo2O4 was attributed to two active species including hydroxyl radical (•OH) and superoxide radical (•O2-) in the catalytic process. The linear range of the proposed sensing platform for S2- was 0.5–10 μM as well as the low limit of detection is 85.9 nM, much lower than the World Health Organization regulations. The sensing platform had been successfully applied to the detection of S2- in tap water and lake water, which provided a convenient method for detecting S2- in wastewater.

Near-Infrared Light Absorbing Silver-Coated Hollow Gold Nanostars for Surface-Enhanced Raman Scattering Detection of Bovine Serum Albumin Using Capping Ligand Exchange

Two novel urchinlike plasmonic nanostructures, hollow gold nanostars (HNSs) and silver-coated hollow gold nanostars (AgHNSs), were synthesized using hollow gold nanospheres (HGNs) as templates. The particle morphology was assessed by transmission electron microscopy (TEM), optical properties were characterized by UV–vis spectroscopy, and elemental composition was evaluated by both inductively coupled plasma-optical emission spectrometry (ICP-OES) and energy-dispersive X-ray (EDX) analysis. Both the HNSs and AgHNSs exhibit tunable structural and optical properties. Their unique star-shaped structure provides the desired “hot spots” for enhancing the electromagnetic (EM) field for surface-enhanced Raman scattering (SERS) applications, while their near-infrared (NIR) absorption is ideal for biomedical applications. A comparative analysis of the relative SERS enhancement using rhodamine 6G (R6G) showed that HNSs reported herein have an order of magnitude higher relative enhancement over previously reported HNSs. Moreover, AgHNSs have a 4-fold increase in the SERS signal compared to HNSs. Discrete dipole approximation (DDA) simulations of electric field enhancement were used to corroborate the experimental findings. The comparison between the experimental and theoretical results suggests that the significant increase in SERS enhancement cannot be completely explained by the larger dielectric constant of silver. The branching of individual spikes, or the increased binding efficacy of the analyte to the nanoparticles, likely also plays an important role. To further explore the applicability of these novel structures, successful capping ligand exchange from citrate to pentanethiol was used to switch the surface charge from negative to positive to facilitate the SERS detection of dried bovine serum albumin (BSA). AgHNSs are stable and effective NIR-absorbing substrates for SERS detection of biological samples. Elemental analyses of AgHNSs, in conjunction with DDA simulations, provide insights into their enhancement mechanism.