Nanorod Arrays Research Articles

Synergistic uranium extraction, organic degradation, and electricity generation by a self-driven photoelectrochemical system with TNR/Si PVC photoanode and copper foam cathode

Herein, we develop a self-driven photoelectrochemical system (SDPS) featuring a TiO2 nanorod array (TNR)/Si photovoltaic cell (Si PVC) photoanode and a porous copper foam (CF) cathode for efficient uranium recovery. Under simulated sunlight illumination, this SDPS simultaneously achieves ∼ 99.4 % UO22+ recovery and ∼ 99.2 % sulfamethoxazole (SMX) removal, with observed rate constant (kobs) value of 0.121 min−1 and 0.029 min−1, respectively, and a maximum power density (Pmax) of 0.89 mW·cm−2 when treating complex wastewater of SMX (10 mg·L−1)-UO22+ (10 mg·L−1). The TNR photoanode absorbs short-wavelength light (λ < 412 nm), generating electron-hole pairs, while the rear Si PVC absorbs transmission light, creating a self-bias potential that drives electrons transfer towards CF cathode, continuously generating electrical energy in the external circuit. The retained holes and derived •OH oxidize SMX, breaking UO22+-SMX complexation, while electrons on the CF reduce UO22+ to insoluble tetravalent uranium (U(IV)) species. This SDPS demonstrates robust performance across varying UO22+ (5 ∼ 40 mg·L−1) and SMX (0 ∼ 40 mg·L−1) concentrations, pH ranges (4 ∼ 8), coexisting ions, and different types of uranium-containing wastewaters, maintaining stability over 20 cycles. It achieves ∼ 97.5 % UO22+ extraction and ∼ 99.8 % SMX removal in simulated seawater, with a Pmax of 1.27 mW·cm−2. This work presents a promising resource strategy for uranium extraction.

Electrochemical Sacrificial Alchemy: Crafting Hollow Hydroxide Hierarchy for Practical Aqueous Energy Storage Solution

AbstractEffective utilization of internal active sites in high‐mass loading electrode materials is essential for advancing practical energy storage. Herein, a novel electrochemical sacrificial alchemy for the first time to directly transform the solid Co‐Ni‐Zn carbonate hydroxide (CH) into its hollow structure with a strategic hierarchical architecture is introduced. In contrast to the complex and often cumbersome procedures of traditional methods, the approach is built on the simple electrochemically induced in situ etching and remodeling process. The experimental and theoretical analyses highlight the significant role of electric field force‐induced Zn sacrificial etching and hydroxide redeposition in creating internal cavities and regenerating external active sites, leading to the final hollow hierarchical structure with primary 1D hollow nanorod arrays and secondary reconstructed 2D nanoflakes, effectively exposing abundant energy storage sites. Benefiting from the synergistic effect, the resulting Co‐Ni‐Zn CH exhibited exceptional electrochemical performance. As proof of concept, a modular pouch‐type hybrid supercapacitor (HSC) composed of Co‐Ni‐Zn CH cathode achieved an ultrahigh energy density of 46.9 Wh kg−1. This device can efficiently power consumer electronics with a faster charging speed compared to commercial shared power banks. This research unveils a facile electrochemical approach for structuring electrode materials in energy storage solutions.

Optical and Structural Properties of Anisotropic ZnS Nanoparticle Suspensions.

We studied the optical and structural properties of highly ordered arrays of surfactant-capped ZnS nanowires (NWs) and nanorods (NRs) in organic suspensions. The photoluminescence (PL) emission measured under different concentrations and postsynthesis washing cycles interestingly showed increasing emission upon decreasing nanoparticle (NP) concentration. Synchrotron small angle X-ray scattering measurements elucidated the liquid-crystal-like structure of the NPs in suspension under different concentrations and temperatures. The NWs are stacked in a simple structure with a hexagonal cross-section, whereas the structure of the NRs is more complex, resembling a smectic-c liquid crystal, and shows unusual thermal expansion versus temperature. The results point out that a certain amount of bound surfactant must be present on the NP surface to maximize the PL intensity.

Ultra‐Low BER Encrypted Communication Based on Self‐Powered Bipolar Photoresponse Ultraviolet Photodetector

AbstractUnderwater visible light communication often faces risks such as susceptibility to external light source interference, signal distortion, and information leakage. The cuprous oxide modified gallium oxide nanorod arrays detector prepared in this study can generate bipolar photocurrents under dual‐wavelength ultraviolet light without external bias voltage. Based on it, the constructed self‐powered ultraviolet ASCII code communication system not only reduce power consumption but also significantly enhance anti‐interference capability. Furthermore, the developed solar‐blind ultraviolet AMI and HDB3 ternary code communication systems can realize non‐visible light secure communication and automatic error correction. Notably, the encrypted communication system assembled using the additive property of bipolar photocurrents can also significantly improve communication security and reliability, whose bit error rate is only 0.26‰. This achievement contributes to technical advancements in underwater channel encryption and provides valuable insights for the further application of encrypted communication coding techniques.

Cu nanorod arrays on Cu foam as an effective and low-priced electrode for hydrazine oxidation

Abstract Synthesis of Cu catalysts for hydrazine oxidation have been focused as an important study. Herein, Cu nanorod arrays on Cu foam (Cu NRAs/CF) were synthesized. Profiting from its structural characteristics, hydrazine oxidation began at -1.03 V, and the current density attained 178.8 mA cm-2 @ -0.6 V. Compared to CF and Cu NPs/CF, Cu NRAs/CF presented a lower charge transfer resistance (Rct) and apparent activation energy (Ea), indicating that hydrazine oxidation on Cu NRAs/CF was associated with comparatively fast kinetics.

Heterostructure WC/Ni/Cu nanorod array towards ultra-long hydrogen evolution durability at room temperature and industrial conditions

Heterostructure WC/Ni/Cu nanorod array towards ultra-long hydrogen evolution durability at room temperature and industrial conditions

Electron field emission property of NiO-decorated ZnO nanorods grown on diamond films

ZnO/micron diamond (MCD) composite structure combines two wide-band gap semiconductor materials, providing stable performance suitable for high-performance electron field emission (EFE) devices operating in various complex environments. Nonetheless, the optical and electrochemical limitations of ZnO constrain its effectiveness. Typically, NiO can compensate these inherent defects in ZnO, thereby enhancing the performance of field-emitting devices. In this research, NiO-decorated ZnO thin films were fabricated on diamond surfaces using hydrothermal/sol-gel two-step method. The impact of varying Ni doping concentrations caused by nickel acetate solutions on the field emission properties was thoroughly investigated. Furthermore, this study involved the fabrication of NiO-decorated ZnO/micron diamond heterojunction composite structures, exploring the impact of the structure on the optoelectronic performance of the devices. The Ni doping concentration increases in the NiO films formed between the ZnO nanorods, the doped Ni exists in the ZnO/MCD composite structure as both Ni2+ and Ni3+, which are important materials for semiconductor electronic devices. The NiO decoration process induced the creation of defect levels within the bandgap of the nanorod array structure, consequently enhancing the photoluminescence performance of ZnO. Furthermore, the interaction between NiO and ZnO facilitated the formation of a p-n junction at the interface, generating an internal electric field. This electric field significantly improved the current conduction field and maximum current density of ZnO, thereby enhancing its electric field emission performance. The optical and electrical properties of ZnO nanorods doped at 0.1M exhibited the most favorable characteristics among all tested samples. At a doping concentration of 0.1 M, the turn-on electric field reaches a minimum value of 0.96 V/μm and the maximum current density J reaches a maximum value of 2.54 mA/cm2. These results offer novel insights for advancing the development of integrated broadband optical devices.

Construction of a novel Mott-Schottky heterostructure gas sensor g-C3N4/SnO2 with layered nanorods array for high-sensitivity acetone detection

Developing exhaled acetone sensors with high performance can be effectively applied to the medical diagnosis and the health monitoring. Herein, a two-dimensional (2D) layered graphitic carbon nitride (g-C3N4) with tunable electronic structure, abundant edge sites, and high stability is proposed, and it is further coupled with stannic oxide (SnO2) by one-step hydrothermal approach to construct a Mott-Schottky heterostructure with layered nanorods array. The exceptional response of the as-fabricated g-C3N4/SnO2 gas sensor to 50 ppm acetone at 100 °C is four times higher than that of the pristine SnO2 sensor. Additionally, the g-C3N4/SnO2 sensor’s remarkable selectivity, long-term stability against acetone gas, and detection limit of 250 ppb are exhibited. The unique hierarchical design and the Mott-Schottky heterostructure creation which validated by electrochemical study, may be in charge of the enhanced acetone sensing capabilities of g-C3N4/SnO2 gas sensor. This work will provide a concise and effective avenue to construct hierarchical composite with Mott-Schottky heterostructure for high-performance acetone gas sensor.

Simulation study of flexible wavefront shaping in Smith-Purcell radiation with aperiodic metagratings

Smith-Purcell radiation (SPR) is a versatile platform for finely tuning nanoscale light across a broad spectral range. This study introduces a theoretical approach for shaping SPR wavefronts using aperiodic metagratings (AMGs). The AMGs consist of arrays of identical metal nano-rods (MNRs), with each MNR's spatial position precisely adjustable. This precise adjustment allows for effective modulation of the spatial phase distribution of SPR. To demonstrate the efficacy of this method, we conduct simulations to achieve diverse wavefront profiles of focusing, deflection, Bessel beams, and Airy beams. Additionally, our approach allows for integrating multiple SPR wavefront functionalities within a combo AMG. By employing the asymmetric L-shaped meta-atom design, we achieve simultaneous SPR polarization conversion and wavefront shaping. This method is promising for developing highly adaptable and multifunctional nanoscale light sources.

Engineering highly reactive nanoarray based on tetrazole-triazole coordination polymer and ammonium perchlorate for advanced energetic microchips

The energetic microchips can be obtained through the integration of energetic materials into microelectromechanical systems (MEMS). Herein, a novel MEMS-compatible energetic composite Cutztr@AP has been prepared by using an in-situ approach. The recrystallized ammonium perchlorate (AP) is uniformly confined within the voids among the Cutztr24 nanorod arrays, resulting in a close contact between Cutztr24 and AP. This structure may effectively improve the mass transfer between the oxidizer and the fuels, thereby enhancing the reactivity. Morphological analysis reveals a uniform distribution of AP within the Cutztr@AP12.5 structure. Consequently, the heat release obtained from non-isothermal decomposition of Cutztr@AP12.5 is 1628 J/g, surpassing the independent heat release from Cutztr24 and AP combined. Benefiting from the enhanced reactivity of Cutztr@AP12.5, a significantly shorter flame duration (190 ms) was obtained with a larger luminous radiation area exceeding 2.5 cm2 comparison to Cutztr24, which has a flame duration of 673 ms with a luminous radiation area of around 1.0 cm2. More importantly, integrating Cutztr@AP12.5 into the energetic microchip reduces the ignition energy to approximately 19.0 mJ, as compared to 25.9 mJ for pure Cutztr24. This study offers a unique method for constructing high-performance energetic microchips.

Core-shell structured carbon nanofiber-supported bristlegrass-like conductive metal‐organic framework Cu3(HHTP)2 nanorod arrays for electrochemical and colorimetric dual-mode detection of dopamine in serum

Dopamine (DA) is a central neurotransmitter that plays a crucial role in human metabolism. Its precise detection is of great importance in disease diagnosis. Compared with single-signal detection methods, colorimetric and electrochemical dual-signal outputs can self-validate the measured data and counteract interference effects, which is expected to provide more reliable detection results. In this paper, carbon nanofiber-supported 3D bristlegrass-like π-conjugated conducting metal–organic frameworks (cMOF) Cu3(HHTP)2 nanorod arrays (Cu3(HHTP)2 NRAs/CNF) catalyst with core–shell structure are synthesized by electrospinning and solvothermal reaction. The obtained catalyst possesses remarkable peroxidase-like activity which can catalyze the colorless 3,3′,5,5′ −tetramethylbenzidine (TMB) to blue oxTMB. The mechanism study showes that ·OH radicals are the main active substances. Meanwhile, the core–shell structure between π-conjugated cMOF and CNF can effectively inhibit the aggregation of Cu3(HHTP)2 nanorods and generate more catalytic active sites, resulting in strong electrocatalytic activity of Cu3(HHTP)2 NRAs/CNF. As a result, a novel dual-mode sensor based on colorimetric and electrochemical are constructed for detecting dopamine (DA) with a good linear relationship ranging from 2.5-60 μM and 0.1–106 μM, and the limit of detection (LOD) are 0.27 μM and 10.1 nM (S/N=3), respectively. This study opens up a new idea for the application of cMOF peroxidase-like enzyme in sensing field.

Controlling the thiourea for optimized growth of CdS nanorod arrays for improved photoelectrochemical water splitting

Energy and the environment are very important issues to secure, preserve and improve our modern lifestyle. The conversion of sunlight into hydrogen and oxygen via photoelectrochemical (PEC) water splitting is one of the most potential routes for clean energy. Cadmium sulfide (CdS) is a promising semiconductor for utilization as a photoanode. In this work, CdS has been grown via the hydrothermal method by optimizing the thiourea concentration. The growth of CdS with equal concentration of Cd2+ and S2-demonstrates the crowded hexagonal-shaped nanorod arrays with small diameter and relatively longer length, and it exhibits the highest photocurrent density due to some factors, such as high length-to-diameter ratio, large reaction area, suitable flat band potential, slow charge recombination rate, fast charge transfer, suitable conduction and valence band edges, and surface reaction kinetics. This work will be of potential to further develop improved nanocomposites of CdS nanorods for hydrogen production and research in related fields.

Efficient pathways for photogenerated charge transfer induced by Co dopants in WO3/TiO2 nanorod arrays

Modifying the energy band structure in heterostructured photocatalysts enhances charge separation efficiency and improves photoelectrochemical (PEC) performance by decreasing the charge transfer barrier. In this study, cobalt doping into WO3/TiO2 core/shell heterojunction nanorod arrays introduces versatile valence states of cobalt altering the oxygen coordination environment around W atoms in WO3, resulting in an increase in W5+ ions and oxygen vacancy defects in WO3 lattice, facilitating the water splitting reaction. Photogenerated electrons transfer easily from the WO3:Co shell to the TiO2 core due to the lower conduction band minimum (CBM) of WO3:Co shell. Moreover, photogenerated holes transfer from the TiO2 core to the WO3:Co shell efficiently due to the higher valence band maximum (VBM) of TiO2 core. The heterostructure has a high photogenerated carrier density (9.89 × 1018 cm-3), improving photoconversion efficiency (2.55 mA cm-2 at 1.23 V vs. RHE) and reducing charge recombination rates (6.51 × 10–4 s-1). Co doping increases the -OH bond on WO3/TiO2 surface, improves its hydrophilicity, and is more conducive to the reaction in aqueous electrolyte. Additionally, the nanorod array structure facilitates PEC reaction kinetics by providing open spaces for mass exchange. This work proposes a feasible strategy for improving photogenerated charge transport and enhancing PEC by combining regulation of the band structure of WO3/TiO2 heterostructures with morphology design.

Microfibrous Carbon Paper Decorated with High-Density Manganese Dioxide Nanorods: An Electrochemical Nonenzymatic Platform of Glucose Sensing.

Nanorod structures exhibit a high surface-to-volume ratio, enhancing the accessibility of electrolyte ions to the electrode surface and providing an abundance of active sites for improved electrochemical sensing performance. In this study, tetragonal α-MnO2 with a large K+-embedded tunnel structure, directly grown on microfibrous carbon paper to form densely packed nanorod arrays, is investigated as an electrocatalytic material for non-enzymatic glucose sensing. The MnO2 nanorods electrode demonstrates outstanding catalytic activity for glucose oxidation, showcasing a high sensitivity of 143.82 µA cm-2 mM-1 within the linear range from 0.01 to 15 mM, with a limit of detection (LOD) of 0.282 mM specifically for glucose molecules. Importantly, the MnO2 nanorods electrode exhibits excellent selectivity towards glucose over ascorbic acid and uric acid, which is crucial for accurate glucose detection in complex samples. For comparison, a gold electrode shows a lower sensitivity of 52.48 µA cm-2 mM-1 within a linear range from 1 to 10 mM. These findings underscore the superior performance of the MnO2 nanorods electrode in both sensitivity and selectivity, offering significant potential for advancing electrochemical sensors and bioanalytical techniques for glucose monitoring in physiological and clinical settings.

One-Dimensional ZnO Nanorod Array Grown on Ag Nanowire Mesh/ZnO Composite Seed Layer for H2 Gas Sensing and UV Detection Applications.

Photodetectors and gas sensors are vital in modern technology, spanning from environmental monitoring to biomedical diagnostics. This paper explores the UV detection and gas sensing properties of a zinc oxide (ZnO) nanorod array (ZNA) grown on silver nanowire mesh (AgNM) using a hydrothermal method. We examined the impact of different zinc acetate precursor concentrations on their properties. Results show the AgNM forms a network with high transparency (79%) and low sheet resistance (7.23 Ω/□). A sol-gel ZnO thin film was coated on this mesh, providing a seed layer with a hexagonal wurtzite structure. Increasing the precursor concentration alters the diameter, length, and area density of ZNAs, affecting their performance. The ZNA-AgNM-based photodetector shows enhanced dark current and photocurrent with increasing precursor concentration, achieving a maximum photoresponsivity of 114 A/W at 374 nm and a detectivity of 6.37 × 1014 Jones at 0.05 M zinc acetate. For gas sensing, the resistance of ZNA-AgNM-based sensors decreases with temperature, with the best hydrogen response (2.71) at 300 °C and 0.04 M precursor concentration. These findings highlight the potential of ZNA-AgNM for high-performance UV photodetectors and hydrogen gas sensors, offering an alternative way for the development of future sensing devices with enhanced performance and functionality.

Enhanced ultraviolet photodetection with Ag nanoparticle-decorated ZnO nanowires and core-shell electrodes

Our study presents the synthesis and characterization of one-dimensional (1-D) zinc oxide (ZnO) nanorod (NR) arrays via low-temperature hydrothermal synthesis, followed by surface modification with silver nanoparticles (Ag NPs). Silver nanowires (AgNWs) are potential alternatives to indium-tin oxide, but their poor stability in atmospheric conditions poses a challenge. To address this, we developed ultrathin Ag/ZnO core-shell structured nanowire networks for ultraviolet-photodetectors (UV-PDs). This cost-effective solution process yielded high transmission (77 %) and low sheet resistance (8.3 Ω/sq). We comprehensively investigated surface morphology, crystalline nature, elemental composition, optical properties, and electrical performance of both synthesized nanorod arrays and NW networks. The UV photodetector exhibited a rise time of approximately 1.35 s and a decay time of 8.01 s, both faster than pristine AgNW electrodes. Additionally, the dark current decreased from 9 nA to 3.5 nA after incorporating Ag/ZnO, accompanied by a significant improvement in photocurrent. These results highlight a promising approach for high-performance UV photodetectors, leveraging the stability and conductivity of Ag/ZnO core-shell NW networks.

Hybrid zinc oxide nanocoating on titanium implants: Controlled drug release for enhanced antibacterial and osteogenic performance in infectious conditions

Implant-associated bacterial infections are a primary cause of complications in orthopedic implants, and localized drug delivery represents an effective mitigation strategy. Drawing inspiration from the morphology of desiccated soil, our group has developed an advanced drug-delivery system augmented onto titanium (Ti) plates. This system integrates zinc oxide (ZnO) nanorod arrays with a vancomycin drug layer along with a protective Poly(lactic-co-glycolic acid) (PLGA) coating. The binding between the ZnO nanorods and the drug results in attached drug blocks, isolated by desiccation-like cracks, which are then encapsulated by PLGA to enable sustained drug release. Additionally, the release of zinc ions and the generation of reactive oxygen species (ROS) from the ZnO nanorods enhance the antibacterial efficacy. The antibacterial properties of ZnO nanorod-drug-PLGA system have been validated through both in vitro and in vivo studies. Comprehensive investigations were conducted on the impact of bacterial infections on bone defect regeneration and the role of this drug-delivery system in the healing process. Furthermore, the local immune response was analyzed and the immunomodulatory function of the system was demonstrated. Overall, the findings underscore the superior performance of the ZnO nanorod-drug-PLGA system as an efficient and safe approach to combat implant-associated bacterial infections. Statement of significanceImplant-associated bacterial infections pose a significant clinical challenge, particularly in orthopedic procedures. To address this, we developed an innovative ZnO nanorod-drug-PLGA system for local antibiotic delivery on conventional titanium implants. This system is biodegradable and features a unique desiccation-like structure that enables sustained drug release, along with the active substances released from the ZnO nanorods. In a rat calvarial defect model challenged with S. aureus, our system demonstrated remarkable antibacterial efficacy, significantly enhanced bone defect regeneration, and exhibited local immunomodulatory effects that support both infection control and osteogenesis. These breakthrough findings highlight the substantial clinical potential of this novel drug delivery system and introduce a transformative coating strategy to enhance the functionality of traditional metallic biomaterials.

Enhanced photoelectric properties of TiO2 nanorod arrays through modulation of precursor concentration

This study synthesized titanium dioxide (TiO2) nanorod arrays and investigated their morphology and defect to the photoelectric response by varying the titanium isopropoxide (TTIP) precursor concentration from 0 to 66 mM. The vertically aligned rutile TiO2 nanorods exhibited film thicknesses ranging from 1 to 4.5 μm when the TTIP concentration equaled or exceeded 33 mM. Their rod length and diameter displayed a linear increase with the TTIP concentration. TiO2 arrays synthesized with a TTIP concentration of 33 mM exhibited the highest photoelectric response, measuring 52 μA/cm2 under xenon-lamp irradiation at a bias voltage of 0.8 V (vs. the Ag/AgCl reference). Notably, photoactivity was observed in the visible-light region as well. Photoluminescence spectra indicated a substantial reduction in electron-hole recombination compared to TiO2 arrays prepared from higher TTIP concentrations. X-ray photoelectron spectroscopy and electron paramagnetic resonance analyses confirmed the presence of oxygen vacancies. Time-resolved photoluminescence spectra corroborated an extended electron lifetime, suggesting that surface oxygen vacancies facilitated the separation of photoexcited charge carriers. The presence of oxygen vacancies, combined with the unique array morphology, resulted in enhanced photocurrent density.

Multipeak ultraviolet lasing based on F-P mode from in-situ ZnO nanowire

Abstract High-quality ultraviolet singlemode and multimode lasing from zinc oxide nanowires are highly desirable. In this paper, we achieve high-Q lasing oscillation in vertically grown Zinc oxide (ZnO) microwires. The broad gain range reaches 13 lasing modes under high-energy excitation. We observe multiple peak emissions from the Fabry-Perot (F-P) lasing mode. In contrast, nanorod arrays with low aspect ratios exhibit amplified spontaneous emission (ASE) due to significant diffraction losses. Our work demonstrates that high-quality ZnO nanowires with an appropriate aspect ratio realize high-Q ultraviolet multipeak lasing based on F-P mode. These findings will benefit the design and fabrication of nanolasers based on nanowires.

MXene introduced between CoNi LDH and NiMoO4 nanorods arrays: A bifunctional multistage composite for OER catalyst and supercapacitors

To improve the electrochemical activity and electrochemical energy storage performance of the catalyst, one of the best approaches is to adjust materials structure reasonably and design of micro-array to enhance specific surface area and expose more active sites. In this work, CoNi-LDH/MXene@NiMoO4 electrode with multistage structure was successfully designed, in which CoNi-LDH was vertically arranged on NiMoO4 nanorods coated with MXene. Oxygen evolution reaction (OER) performance was improved through the adjustment of LDH by MXene. The electrode has an excellent OER activity, which the overpotential is 222 mV at 100 mA cm−2. In addition, it can maintain high efficiency and stable operation for 120 h. The overall water-splitting (OWS) electrolytic cell was assembled with CoNi-LDH/MXene@NiMoO4 electrodes, which exhibited a low cell voltage (1.56 V) at 10 mA cm−2. Moreover, the assembled OWS electrolytic cell can operate stably under the low voltage by small-scale solar power generation and thermal power generation. Furthermore, CoNi-LDH/MXene@NiMoO4 electrode also showed good potential in electrochemical energy storage. This work opened a new avenue for MXene to regulate the activity of transition metal-based catalysts. The efficient preparation of clean energy by the interaction of MXene and transition metal groups show great prospects.