Nanorod Bundles Research Articles

Morphology Controled LiFePO4 Electrodes Via Polyol Refluxing for Enhanced Lithium-Ion Battery Performance

In the synthesis of LiFePO4 cathodes with secondary nanorod structures and nano-plate morphologies, researchers utilized a polyol refluxing process. Notably, we achieved this without the use of characteristic structure directing agents. Through varying the reaction time, they were able to modulate the morphological characteristics of the synthesized samples.X-ray diffraction studies conducted on the prepared samples indicated a highly crystalline nature. This suggests that the synthesized cathodes possessed a robust and ordered atomic structure, which is crucial for their electrochemical performance.Electron microscopy investigations provided insights into the morphology of the samples obtained at different reaction times. Samples produced after 1 to 16 hours of polyol reaction exhibited secondary nanorod bundles. However, the sample recovered after 32 hours of polyol reaction displayed a distinct nano-plate morphology. These observations highlight the influence of reaction time on the final morphology of the synthesized cathodes.The dimensions of the obtained samples ranged from a few tens to a few hundred nanometers. This nano-scale size is advantageous for enhancing the electrode's surface area, which can facilitate rapid ion diffusion and electron transport during battery cycling.When employed in lithium test cells, the LiFePO4 cathodes synthesized for different durations delivered varying discharge capacities. Specifically, cathodes prepared under 1, 4, 8, 16, and 32 hours of reaction time exhibited discharge capacities of 161, 162, 171, 143, and 155 mAhg−1, respectively. Notably, all samples displayed a well-defined discharge plateau at 3.4 V, indicating stable electrochemical behavior during cycling.Remarkably, among the prepared electrodes, the LiFePO4 nanorod bundle cathode synthesized under 1 hour reaction time demonstrated the highest average reversible capacities. It maintained capacities of 123 and 103 mAhg−1 at C-rates as high as 3.2 and 6.4 C, respectively. This highlights the importance of reaction time in controlling the electrochemical performance of the synthesized cathodes.The crystal growth mechanism during the polyol refluxing method can be elucidated through several stages. These include precursor dissolution and nucleation, oriented crystal growth and alignment through self-assembly, aggregation, partial dissolution, and finally, complete re-crystallization. Understanding these mechanisms is essential for optimizing the synthesis process and tailoring the properties of LiFePO4 cathodes for various applications. Tarascon JM, Armand M. Issues and challenges facing rechargeable lithium batteries. Nature 2001;414:359–67Amatucci GG, Tarascon JM, Klein LC. CoO2, the end member of the LixCoO2 solid solution. J Electrochem Soc 1996;143:1114–23Ravet N, Chouinard Y, Magnan JF, Besner S, Gauthier M, Armand M. Electroactivity of natural and synthetic triphylite. J Power Sources 2001;97–98:503–7 Figure 1

Large-Scale Synthesis of ZnO Nanorods Bundles by Microwave Heating Method: Growth Mechanism and Possibility of Controllable Growth of Nanoneedle

This paper has presented a novel method for the synthesis of regular and reproductive ZnO nanostructures by microwave heating. Unlike the previous studies, it has focused on ZnO nanostructures grown on the Si wafer used as a cover rather than on the precursor top and the results show that ZnO nanostructures with different shapes depending on the amount of mixture and the position in the Si wafer grow on the regular and reproductive basis. In the center of the Si wafer, short and coarse ZnO nanorods have grown, and on the outer edges, the structure of bundles consisting of ZnO nanorods with much longer lengths and smaller diameters has been synthesized. Morphology of ZnO nanorods was characterized by using scanning electron microscope and the nanorods grown on the outer edges had a mean diameter of 200[Formula: see text]nm and were up to [Formula: see text]m long. In order to elucidate the growth mechanism of nanorods, we have carried out SEM, energy dispersive spectrometer (EDS) and XRD characterization, which shows that ZnO nanorods have grown according to VLS mechanism. A controllable growth method of ZnO nanoneedle is suggested.

Strategies of realizing NO2 detections with enhanced selectivity and anti-humidity based on snowflake-like in-situ grown ZIF-8/ZnOHF composites

Realizing nitrogen dioxide (NO2) detections based on semiconductor-based gas sensors with high tolerance to humidity conditions is deemed to be a long-term challenge. To independently acknowledge the physiosorbed-water influence mechanism on semiconductor-based sensors, hydrophobic zeolitic imidazolate framework-8 (ZIF-8) covered chemisorbed-oxygen-nonexistence zinc hydroxyfluoride (ZnOHF) snowflake-like nanorod bundles are synthesized for NO2 detections with non-hindrance of interfering gases and high humidity in our work. Gas-sensing testing results display that the 0.6ZIF-8/ZnOHF-based gas sensor provides an optimum NO2 response of 12.1–10 ppm NO2 at the operating temperature of 200 ℃ with excellent NO2 selectivity. As the relative humidity (RH) increases from 20% RH to 80% RH, the response of the 0.6ZIF-8/ZnOHF sensor shows a marginal fluctuation of only 13%, exhibiting outstanding anti-humidity characteristics towards NO2 detections, the outperformed NO2 selectivity and humidity tolerance of which are greatly attributed to the unique band structures of ZnOHF and the surficial hydrophobic treatment by ZIF-8, which is further validated via In-situ diffuse reflection infrared Fourier transform spectroscopy (In-situ DRIFTS) and electronic structure analyses. Humidity impact on ZnOHF poses a persuasive evidence for establishing the separate physiosorbed water interfering mechanism on semiconductors. This work endows a perspective on optimizing humidity tolerance for semiconductor-based sensors at low operating temperature.

Investigation on visible-light induced photocatalytic activity for pure, Ce:doped TiO2 and B:Ce co-doped TiO2 catalysts

In this study, the photocatalytic activity of pristine and Boron (B) - Cerium (Ce) co-doped titanium dioxide (TiO2) have been investigated towards the degradation of aqueous solution of Methylene Blue (MB) dye under visible light activity. The B:Ce co-doped TiO2 catalyst was successfully prepared by co-precipitation method. The structural, optical, and morphological properties of the synthesized samples were characterized by different techniques. PXRD analysis revealed that the prepared nanoparticles (NPs) have tetragonal crystal structures with an anatase phase. In FESEM analysis, the different morphologies (spherical and nanorod bundles) were observed from the synthesized Pure, Ce:TiO2 and B:Ce co-doped TiO2 NPs. The UV-Vis DRS and PL studies showed that B:Ce doped TiO2 exhibited enhanced visible light absorption activity and less electron-hole pair recombination rate. The findings demonstrated the incorporation of B and Ce ions into the TiO2 lattice, which can increase the absorption region to visible light and prevent the recombination rate of e-/h+ pairs. The results of the photocatalytic experiment show that B-Ce co-doped TiO2 improves photodegradation performance, with 97%, 98.0%, and 99% of the MB dye decomposing within 150 min of illumination under simulated visible light irradiation.

Synthesis of Mn2+ and Pr3+ co-doped Zn2GeO4-graphene quantum dot nanorod bundles as an optical probe for sensing pH and temperature and for information encryption

This paper reports the synthesis of a Mn2+ and Pr3+ co-doped Zn2GeO4 optical probe by introducing boron-doped and histidine- and serine-functionalized graphene quantum dots (BHS-GQD) to Mn2+/Pr3+-Zn2GeO4.

Cobalt phosphate nanorod bundles for efficient supercapacitor and oxygen evolution reaction applications and their temperature dependence

Cobalt phosphates have been synthesized using a successive ionic layer adsorption and reaction (SILAR) method and studied their supercapacitor and oxygen evolution reaction performances.

Interface construction of micro/nano hierarchical structure to enhance the tribological performance of carbon fabric/phenolic composite

Carbon fabric (CF)/polymer composites are potential lubricating materials, which could be used for plane bearing lining, sliding guide rails, and other moving parts of advanced equipment. But the low bonding strength at the interface between the carbon fibers and the polymer matrix is a great challenge to developing high-performance CF/polymer composites. In this study, the CF is coated with an active transition layer using high-adhesion polydopamine (PDA) as an ideal plate for the TiO2 micro/nano hierarchical structure to construct CF-PDA-TiO2. This hierarchical structure is made of micro-bundles, each composed of numerous nanorods, and decorated on CF surface densely and uniformly. The interfacial combination of CF-PDA-TiO2 and phenolic resin (PF) shows excellent performance, and the interlaminar shear strength (ILSS) of CF-PDA-TiO2/PF is improved from 10.48 MPa to 37.22 MPa, attributed to the improved interfacial physicochemical interaction. Furthermore, the tribological performance of CF-PDA-TiO2/PF with size of Φ30 mm✕5 mm is characterized by sliding against 440C stainless steel ball with diameter of 8 mm using ball-on-disc sliding wear tester (MPX-3). The tribological results demonstrate that the friction coefficient and wear rate of CF-PDA-TiO2/PF are reduced by 37.91% and 77.6%, compared to CF/PF. Moreover, the CF-PDA-TiO2/PF maintains low friction coefficient and wear rate under high-load and high-speed sliding conditions. This is mainly because TiO2 nanorod bundles exhibit micro/nano multi-scale interfacial enhancement, promoting stress distribution and micro-cracks deflection etc. Moreover, TiO2 nanorod bundles could promote the formation of a uniform transfer film to decrease friction and wear. This work implies that interface construction of micro/nano hierarchical structure is a promising way to enhance the tribological performance of CF/polymer composites.

Nanoscale morphology tailoring in plasma deposited CN x layers

Magnetron discharge plasma was applied for the synthesis of CN x thin layers using methane and nitrogen gas precursors. The incorporation of nitrogen in the carbon network resulted in the dramatic evolution of growth morphology: from a ‘buried’ porous layer observed at low nitrogen incorporation to aligned bundles of nanorods grown perpendicular to the substrate surface at maximum discharge power and nitrogen flow. The films deposited at the low discharge power and high nitrogen incorporation exhibited a mesoporous sponge-like morphology after vacuum annealing. Relevant physical mechanisms responsible for the formation of nano- and mesoshaped morphology are discussed in terms of the effects of internal mechanical stresses and plasma etching. In addition, the sensing properties of the sponge-like layer were preliminarily examined in water vapor and ammonia ambients. The CN x films showed enhanced sensitivity to ammonia and reverse electrical response to moisture in comparison with a nitrogen-free nanoporous carbon film, which were assigned to modification of the electronic properties of the nitridated surface.

Impact of cation substitution in NiCo2O4 spinel on morphology and electrochemical performance

Nanostructured NiCo2O4 spinel is the most appealing candidate to be used as the electrode for supercapacitors due to its significant merits such as eco-friendliness, low cost and easy availability. Introduction of a secondary metal cation into the host NiCo2O4 could provide more electroactive sites with rich redox chemistry. Herein we report the influence of cation (Zn/Mn) doping on the physicochemical and electrochemical properties of easily synthesized NiCo2O4 spinel. After being doped with Zn/Mn the morphology of NiCo2O4 was notably changed and specific capacitance of NiCo2O4 was greatly enhanced. Mn doped NiCo2O4 nanorod bundles store more internal surface charge than Zn doped NiCo2O4 flowers. A maximum specific capacitance of 1494 F/g was delivered by Mn doped NiCo2O4 nanorod bundles with a good rate capability (capacity retention of 64 % from 1 to 20 A/g) and excellent cycling stability (88.6% of initial value after the completion of 5000 cycles). An asymmetric device fabricated using Mn substituted NiCo2O4 as the positive electrode achieved an energy density of 12 Wh/kg at a power density of 427 W/kg and could efficiently light up a light emitting diode.

Limpet teeth microstructure unites auxeticity with extreme strength and high stiffness.

Materials displaying negative Poisson's ratio, referred to as auxeticity, have been found in nature and created in engineering through various structural mechanisms. However, uniting auxeticity with high strength and high stiffness has been challenging. Here, combining in situ nanomechanical testing with microstructure-based modeling, we show that the leading part of limpet teeth successfully achieves this combination of properties through a unique microstructure consisting of an amorphous hydrated silica matrix embedded with bundles of single-crystal iron oxide hydroxide nanorods arranged in a pseudo-cholesteric pattern. During deformation, this microstructure allows local coordinated displacement and rotation of the nanorods, enabling auxetic behavior while maintaining one of the highest strengths among natural materials. These findings lay a foundation for designing biomimetic auxetic materials with extreme strength and high stiffness.

Preparation of Cu modified g-C3N4 nanorod bundles for efficiently photocatalytic CO2 reduction

Carbon nitride-based photocatalysts for CO2 reduction have received great attention. The introduction of transition metals can effectively improve the photocatalytic efficiency of carbon nitride. However, how to introduce transition metals into carbon nitride in more ways remains a challenge. Herein, the Cu modified g-C3N4 nanorod bundles (CCNBs) were prepared by chemical vapor co-deposition using the mixture of urea and chlorophyllin sodium copper salt as precursor. The prepared CCNBs exhibited excellent photocatalytic activity for CO2 reduction. The unique hierarchical structure was beneficial to enhance light harvesting. Besides, the introduction of uniformly dispersed Cu further improved the absorption capacity of visible light, increased active sites, and promoted the separation and transfer of carriers. The CO yield of CCNBs was 5 times higher than that of bulk g-C3N4, and showed excellent stability in cycle experiments. This work provides a strategy to prepare carbon nitride-based photocatalysts for efficient CO2 reduction.

One-pot method synthesis of the multi-morphology Sb2S3 superstructure increasing the sodium storage capacity and expanding the interlayer spacing

Antimony sulfide has become a promising negative electrode material for sodium-ion batteries (SIBs) because its low toxicity, cost and high theoretical specific capacity. But enhancing its electrochemical performance still poses a big challenge. Therefore, the solvothermal method was used to construct the self-assembled flower-like Sb2S3 microspheres into bundles of Sb2S3 nanoneedles and nanorods in situ. The structural characterization shows that the increased (110) interplanar spacing can effectively improve the electrochemical activity. This site is based on micro-nano structure and multi-dimensional synergistic effect, which can effectively improve its sodium storage performance. When Sb2S3 nanoneedles and Sb2S3 microspheres are used as negative electrode materials for SIBs, at current densities of 0.1 A g−1 and 0.05 A g−1, the specific charging capacity is 355.7 mAh g−1 and 790.5 mAh g−1, respectively. This proves its great potential in the industrial production of sodium ion batteries.

Novel homo-epitaxial approaches in solvothermal synthesis for preparing surface tethered uni-directionally oriented zinc oxide micro and nano structured arrays

Surface aligned, uni-directionally grown, hexagonal nanorod bundles and microrod pillared arrays of zinc oxide (ZnO), were synthesized through a simple, homo-epitaxial growth approach. A uniform layer of ZnO seed was initially prepared on cleaned glass substrates by dip coating and calcination. Uni-directionally oriented ZnO micro– nano structures were subsequently developed on the seeded glass substrates through solvothermal methods, by employing equi-molar solutions of zinc nitrate and hexamethylenetetramine. The reaction parameters that control the surface morphologies and crystal orientations were explored. A solution exchange process was also carried out to prepare perpendicularly aligned ZnO nanorod arrays. The structural and functional features of the resultant samples were studied and discussed with the help of X-ray diffractometry, scanning electron microscopy, high-resolution transmission electron microscopy and photoluminescence spectrophotometry. A plausible structure dependent growth mechanism of the morphologically varied ZnO was also proposed.

H2S sensing material Pt-WO3 nanorods with excellent comprehensive performance

The Pt-loaded WO3 materials have been synthesized via simple hydrothermal and chemical reduction methods. The microstructure of prepared Pt-WO3 exhibits as nanorods consisting of bundles of finer nanorods and the Pt nanoparticles with a size of ca. 5 nm loaded on the surface of WO3. The gas sensing measurements of Pt-WO3 material show excellent gas sensing selectivity to H2S compared with many other pollution gases (e.g. NO2, SO2, NH3, CO and CO2). In particular, 0.2 at% Pt-WO3 exhibits extremely high response (1638–10 ppm H2S), short response/recovery time (42 s/37 s) and low detection limit (1.27–5 ppb H2S) at 200 °C. The superior performance of 0.2 at% Pt-WO3 compared with pure WO3 mainly originate from its modulating action to conductive band electrons of WO3 and its catalysis to the chemisorption reaction on the surface.

Chelate mediated synthesis of novel Mn2V2O7 and MnV2O6 materials with hierarchical morphological structures and improved redox behavior via multi-walled carbon nanotubes for asymmetric supercapacitors

Designing different nano/microstructural geometries with porous properties is of great attention, allowing impressive electrochemical properties in energy storage technology. Herein, we report the manganese vanadium oxides of Mn2V2O7 and MnV2O6 with different morphologies by a most adaptable hydrothermal technique using three types of chelating agents (citric acid, ethylenediaminetetraacetic acid, and hexamethylenetetramine). The materials reveal a hierarchical thorny structure, i.e., an orientation form of microrods and nanorod bundles, and their comparative electrochemical analysis is performed. Furthermore, the thorny sphere morphology of MVO material is combined with the multi-walled carbon nanotubes and it reveals the enhancement in the specific capacity as compared to pristine. This electrode material exhibits superior capacity retention of 97% even after 4000 cycles at 5 A g−1 with its corresponding coulombic efficiency of 99%. Additionally, a pouch-like asymmetric supercapacitor device exhibits a high energy and power density values of 26.6 Wh kg−1 and 2875 W kg−1, respectively. Eventually, various low voltage electronic devices such as a mortar fan and blue light-emitting diodes are powered-up using the devices to test the real-time applications in the field of energy storage.

Engineering unique Fe(SexS1−x)2 nanorod bundles for boosting oxygen evolution reaction

Fe-based electrocatalysts have attracted significant attention on account of the possibility for the realization of low-cost, high efficiency, and stable oxygen evolution reaction (OER) in alkaline solution. In this study, we present a new type of Fe(SexS1−x)2 nanorod bundles, which were successfully synthesized via a simple one-step hydrothermal method. We further demonstrate the applicability of these structures as electrocatalysts for OER application. We reveal that the incorporation of S into FeSe2 cause lattice strain and lattice defect, which is beneficial to expose more active sites and optimize the electronic structure, and hence the Fe(SexS1−x)2 composites display favorable catalytic for OER. More interestingly, the as-prepared Fe(Se0.5S0.5)2 catalyst exhibits the best OER performance with an overpotential at 10 mA·cm−2 of 247 mV, a low tafel slope of 54 mV/dec, and excellent catalytic stability. This work is expected to open a new door to discover other Fe-based materials as efficient catalysts for renewable energy.

Atomic Level Interface Control of SnO2-TiO2 Nanohybrids for the Photocatalytic Activity Enhancement

This review article highlights atom-level control of the heterojunction and homojunction in SnO2-TiO2 nanohybrids, and the effects on the photocatalytic property. Firstly, a comprehensive description about the origin for the SnO2-TiO2 coupling effect on the photocatalytic activity in the conventional SnO2-TiO2 system without heteroepitaxial junction is provided. Recently, a bundle of thin SnO2 nanorods was hetero-epitaxially grown from rutile TiO2 seed nanocrystals (SnO2-NR#TiO2, # denotes heteroepitaxial junction). Secondly, the heterojunction effects of the SnO2-NR#TiO2 system on the photocatalytic activity are dealt with. A novel nanoscale band engineering through the atom-level control of the heterojunction between SnO2 and TiO2 is presented for the photocatalytic activity enhancement. Thirdly, the homojunction effects of the SnO2 nanorods on the photocatalytic activity of the SnO2-NR#TiO2 system and some other homojunction systems are discussed. Finally, we summarize the conclusions with the possible future subjects and prospects.

An asymmetric supercapacitor based on controllable WO3 nanorod bundle and alfalfa-derived porous carbon.

A novel asymmetric supercapacitor (ASC) is assembled on the basis of an inerratic hexagonal-like WO3 nanorod bundle as a negative electrode and graphene-like alfalfa-derived porous activated carbon (APAC) as the positive electrode in 1 M H2SO4 aqueous electrolyte. The WO3 nanostructures prepared at pH of 1.6, 1.8, 2.0, 2.5 and 3.0 display hexagonal disc-like, nanorod bundle, inerratic hexagonal-like, sphere-like, and needle-shaped nanorod morphology. WO3-2.0, which was prepared at a pH of 2.0, exhibits high specific capacitance (415.3 F g−1 at 0.5 A g−1). APAC-2, which had the mass ratios of dried alfalfa and ZnCl2 as 1 : 2, showed a 3D porous structure, large surface area (1576.3 m2 g−1), high specific capacitance (262.1 F g−1 at 0.5 A g−1), good cycling stability with 96% of initial specific capacitance after 5000 consecutive cycles. The ASC assembled with WO3-2.0 and APAC-2 exhibits high energy density (27.3 W h kg−1 at a power density of 403.1 W kg−1), as well as good electrochemical stability (82.6% capacitance retention after 5000 cycles). Such outstanding electrochemical behavior implies that the electrode materials are promising for practical energy-storage systems.

Ultrafast conversion of carcinogenic 4-nitrophenol into 4-aminophenol in the dark catalyzed by surface interaction on BiPO4/g-C3N4 nanostructures in the presence of NaBH4.

The heterogeneous catalytic conversion of pollutants into useful industrial compounds is a two-goals at once process, which is highly recommended from the environmental, economic, and industrial points of view. In this regard, design materials with high conversion ability for a specific application is required to achieve such a goal. Herein, the synthesis conditions for the fabrication of BiPO4 nanorod bundles supported on g-C3N4 nanosheets as heterojunction composites was achieved using a facile ex situ chemical deposition for the reductive conversion of carcinogenic 4-nitrophenol (4-NP) into 4-aminophenol (4-AP). To better understand the mechanistic reduction pathways, BiPO4/g-C3N4 composites with varying ratios where obtained. The morphology and structure of BiPO4/g-C3N4 composites were checked using several methods: XRD, FE-SEM, HRTEM, XPS, and FT-IR, and it was found that hexagonal phase BiPO4 nanorod bundles were randomly distributed on the g-C3N4 nanosheets. Overall, the reduction ability of BiPO4/g-C3N4 composites was far better than bare BiPO4 and g-C3N4. A total reductive conversion of 4-NP at a concentration of 10 mg L−1 into 4-AP was found with 50% BiPO4/g-C3N4 composite within only one minute of reaction. Moreover, the presence of reducing agent (NaBH4) enhanced the kinetic rate constant up to 2.914 min−1 using 50% BiPO4/g-C3N4, which was much faster than bare BiPO4 (0.052 min−1) or g-C3N4 (0.004 min−1). The effects of some operating parameters including the initial concentration of 4-NP and catalyst dosage were also evaluated during the experiments. BiPO4/g-C3N4 showed great stability and recyclability, wherein, the catalytic reduction efficiency remains the same after five runs. A plausible 4-NP reduction mechanism was discussed. The high catalytic activity with the good stability of BiPO4/g-C3N4 make it a potential candidate for the reduction of nitroaromatic compounds in real wastewaters.

Synthesis and Characterization of Pollen Extract Mediated Gold Nanostructures

There is an increasing demand in the synthesis of shape and size-controlled gold nanostructures (Au NSs) with greener methods. Therefore, we aimed to synthesize differently shaped and sized Au NSs using a greener technique under ambient conditions. In this study, we utilized pollen extracts of Corylus avellana, Juniperus oxycedrus and Pinus nigra species (collected from Kastamonu region of Turkey) for the synthesis. The extraction was performed in water in order to recover water soluble content from the pollen grains. The extracts were used to stabilize, and shape/size direct the HEPES (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid) buffer synthesized Au NSs. UV-vis, powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) characterizations proved synthesis of spherical, anisotropic and large Au NSs with this benign approach. The obtained Au NSs were possible to separate small and large Au NSs through centrifugation. Chemistry of pollen extracts played key role on morphology and stability of the Au NSs. The findings, for the first time, is revealing the synthesis of large Au nanorod bundles (>300 nm) along with hexagonal and spherical Au NSs under ambient conditions using pollen grain extracts, whose maturation took 24h.