Nanorod Arrays Research Articles

TiO2 nanorod arrays modified by NiFe-layered double hydroxide nanosheets for boosting photoelectrochemical water splitting

TiO2 nanorod arrays modified by NiFe-layered double hydroxide nanosheets for boosting photoelectrochemical water splitting

Interfacial [S─Cu─C] Bonds Induced π-d Electron Coupling Toward Modulating Charge Transfer for Efficient Solar Water Oxidation.

Regulating the interfacial electric field to achieve rapid charge transfer is crucial for superior photoelectrochemical water splitting. Herein, the ultra-thin hydrogen-substituted graphdiyne (HsGDY) is precisely assembled on the surface of CdS nanorod array (Cu-CdS-HsGDY) by an in situ polymerization strategy. The strong π-d electron coupling is aroused by the delocalized π electrons of HsGDY and the delocalized d electrons of CdS through the interfacial [S─Cu─C] bonds. The strong interfacial electric field can effectively promote the charge localization distribution and reduce the charge transfer resistance. The optimized Cu-CdS-HsGDY photoanode obtain a photocurrent density as high as 4.83 mA cm-2 at 1.23 V versus reversible hydrogen electrode in neutral electrolyte solution under AM 1.5G illumination, which is 6.8 times that of the pristine CdS. Moreover, the photoanode maintains an initial photocurrent density of 84% within 4 h without any assistance of sacrificial agents, which is a rather competitive performance of similar sulfide photoanodes. The mechanism of strong π-d electron coupling on interfacial charge transfer and surface reaction kinetics is investigated by transient spectroscopy measurements, density functional theory calculation, and finite element simulation analysis. This work provides new insights into designing a reasonable interface structure to regulate charge transfer for achieve efficient PEC water splitting.

Unraveling the Synergistic Role of Kinks in Zig-Zag Ag2Se Nanorod Arrays for High Room-Temperature zT and Improved Mechanical Properties: Experimental and First-Principles Studies.

Flexible thermoelectric materials are usually fabricated by incorporating conducting or organic polymers; however, it remains a formidable task to achieve high thermoelectric properties comparable to those of their inorganic counterparts. Here, we present a high zT value of 1.29 ± 0.31 at room temperature in the hierarchical zig-zag Ag2Se nanorod arrays fabricated using the glancing angle deposition (GLAD) technique followed by a facile selenization process. The high zT value at 300 K is ascribed to the ultrahigh power factor of 3101 ± 252 μW/m-K2 and the reduced thermal conductivity of 0.72 ± 0.01 W/mK. Based on ab initio computational and experimental evidence, we reveal that kinked Ag2Se nanorod arrays consisting of rough interfaces modulate the lattice thermal conductivity up to 48.5% at room temperature. The modulation results from interchanging of phonon modes at kink points and enhanced scattering from a large number of rough interfaces. Further, benefiting from kinked hierarchy, a notable improvement in the mechanical performance is observed for zig-zag Ag2Se nanorods which is confirmed by nanoindentation measurements. The synergic improvement in thermoelectric and mechanical performance not only unravels a paradigm to harness thermoelectric heat but also offers deeper insights into tuning the mechanical properties of inorganic thermoelectric materials.

Self-powered Sb2S3 photodetectors with efficient carrier transport enabled by compact vertical TiO2 nanorods.

Antimony sulfide (Sb2S3) photodetectors (PDs) possess extensive application prospects. Efficient carrier transport of a PD significantly affects the detectivity and response speed. Herein, we propose an all-inorganic self-powered Sb2S3 PD based on vertical TiO2 nanorods (NRs). The spray-coated 15-nm TiO2 thin film as a seed layer ensures the growth of compact vertical TiO2 nanorod arrays by the hydrothermal method. One-dimensional TiO2 nanorods facilitate photocarrier separation and transport to enhance device performance. Ultimately, the Sb2S3 PD achieves a responsivity of 0.29 A/W, a specific detectivity of 3.37 × 1012 Jones, and a response time of 7.8 µs, showing great potential in commercial applications.

Optimizing Charge Separation and Transport: Enhanced Photoelectrochemical Water Splitting in α-Fe2O3/CZTS Nanorod Arrays

This study explores the enhancement of α-Fe2O3 (hematite) nanorod arrays for photoelec-trochemical applications by constructing a Cu2ZnSnS4 (CZTS) heterojunction. While α-Fe2O3 offers good stability, a low cost, and environmental benefits, its efficiency is limited by slow oxygen evolution kinetics, high carrier recombination rates, and low conductivity. By introducing CZTS, a material with strong light absorption and charge transport properties, we enhance the separation of photogenerated charge carriers, reduce charge transfer resistance, and increase the carrier concentration, thereby boosting the overall photoelectrochemical performance. The experimental results show that a modified FC-15 photoanode achieves a photocurrent density of 3.40 mA/cm2 at 1.60 V vs. RHE, a substantial increase compared to 0.40 mA/cm2 for unmodified α-Fe2O3. Band gap analysis reveals a reduced band gap in the FC-15 material, enhancing light absorption and boosting the photoelectrocatalytic performance. In photoelectrochemical water-splitting tests, the FC-15 photoanode achieves a hydrogen production rate of 41.6 μmol/cm2/h, which is significantly improved over the unmodified sample at 5.64 μmol/cm2/h. These findings indicate that the CZTS/α-Fe2O3 heterojunction effectively promotes charge separation, enhances charge transport, and improves light absorption, substantially increasing photocatalytic efficiency. This heterojunction approach offers new insights and technical strategies for developing photocatalytic materials with potential applications in renewable energy.

Electroless Ag nanoparticle deposition on TiO2 nanorod arrays, enhancing photocatalytic and antibacterial properties

Hypothesis: The use of a high surface area, hence small nanoparticles for photocatalysis, makes them difficult to remove from solution. Producing photocatalysts on substrates would alleviate this limitation. Adding heterojunctions to photocatalysts, for example, TiO2/Ag, could improve photocatalytic performance due to Schottky junction formation and introduce antibacterial properties.Experiments: TiO2 nanorod arrays were synthesised on a substrate via a hydrothermal approach, on which Ag nanoparticles were deposited using an electroless plating technique with varied deposition times and metal precursor concentrations. Photocatalytic performance was evaluated by monitoring Rhodamine B (RhB) degradation under ultraviolet light and antibacterial properties of the films tested using Methicillin-resistant Staphylococcus aureus.Findings: The Ag nanoparticle content was controlled by the Ag deposition process. The TiO2/Ag nanorod array containing 6.6 atomic% Ag as nanoparticles of ∼ 25 nm in diameter degraded 88 % of the RhB in 6 h compared to 54 % degradation for bare TiO2 nanorods under the same reaction conditions. Decreased photoluminescence with heterojunction formation would indicate electron transfer from the TiO2 into the Ag nanoparticles, thereby reducing charge carrier recombination. The antibacterial test conducted in the dark revealed enhanced performance for the TiO2/Ag sample compared to TiO2 nanorods against Methicillin-resistant Staphylococcus aureus after 16 h exposure with a death rate of 84 %.

Ultra-thin FeVO4 modified Al-doped ZnO nanorods photoanode towards efficient photoelectrochemical water oxidation

Fabricating of high-performance photoanodes played an important role in achieving efficient conversion of solar energy to hydrogen energy. Herein, Al-ZnO/FeVO4 core–shell nanorods arrays (NRs) was constructed through a simple two-step method to form type-II heterojunction. Compared with the Al-ZnO substrate (0.55 mA/cm2), the modified Al-ZnO/FeVO4 photoanode exhibited superior photocurrent density, with an optimal photocurrent density of 1.13 mA/cm2 at 1.23 V vs. RHE (AM 1.5G). Heterogeneous structures suppressed the photoinduced bulk recombination of charge carriers and improved the separation efficiency of charge carriers. More importantly, the ultra-thin FeVO4 modification layer weakened surface capture states, increased photovoltage, and promoted interfacial charge transfer dynamics. This work provided new ideas for designing high-performance photoanodes.

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.