Leaf-like Nanostructures Research Articles

Versatile, durable conductive networks assembled from MXene and sericin-modified carbon nanotube on polylactic acid textile micro-etched via deep eutectic solvent

Integration of polylactic acid (PLA) textiles with conductive MXene holds great promise for fabricating green electronic textiles (e-textiles) and reducing the risk of electronic waste. However, constructing robust conductive networks on PLA fibers remains challenging due to the susceptibility of MXene to oxidation and the hydrophobicity of PLA fibers. Here, we demonstrate a versatile, degradable, and durable e-textile by decorating the deep eutectic solvent (DES) micro-etched PLA textile with MXene and sericin-modified carbon nanotube hybrid (MXene@SSCNT). The co-assembly of MXene with SSCNT in water not only enhanced its oxidative stability but also formed synergistic conductive networks with biomimetic leaf-like nanostructures on PLA fiber. Consequently, the MXene@SSCNT coated PLA textile (MCP-textile) exhibited high electrical conductivity (5.5 Ω·sq-1), high electromagnetic interference (EMI) shielding efficiency (34.20 dB over X-band), excellent electrical heating performance (66.8 ℃, 5 V), and sensitive humidity response. Importantly, the interfacial bonding between the MXene@SSCNT and fibers was significantly enhanced by DES micro-etching, resulting in superior wash durability of MCP-textile. Furthermore, the MCP-textile also showed satisfactory breathability, flame retardancy, and degradability. Given these outstanding features, MCP-textile can serve as a green and versatile e-textile with tremendous potential in EMI shielding, personal thermal management, and respiratory monitoring.

Coupling of V2O5 structural design and electrolyte modulation toward stable zinc-ion battery

Layered vanadium oxides possess abundant crystal structures and multiple redox states, which account for excellent specific capacity for zinc ion batteries (ZIBs). However, vanadium-based cathodes typically suffer from structural instability and component dissolution, leading to inferior cyclic stability and rate performance. Herein, porous V2O5 slender leaf-like nanostructure anchored on carbon cloth (CC) is synthesized via electrodeposition and subsequent calcination. Taking advantage of the distinctive hierarchical structure and the introduction of propylene carbonate (PC) electrolyte additives, the free-standing VO-C2PC electrode provides a maximum reversible capacity of 555 mA h g−1 at 0.3 A g−1, and high capacity retention of 180 mA h g−1 after 5000 cycles at 10 A g−1. Even at a high mass loading, the VO-C2PC exhibits excellent Zn storage capability and stability. Furthermore, the Zn2+ storage mechanism reveals the gradual transformation of V2O5 into stable zinc pyrovanadate (ZVO) phase, which improves the stable Zn2+ storage capability. This study provides valuable insights into the construction of advanced electrodes and the design of novel electrolytes for high-performance ZIBs.

Temperature-modulated formation of polyamide layer for enhanced organic solvent reverse osmosis (OSRO) performance

Organic solvent reverse osmosis (OSRO) has gained extensive attention for chemical separation because of its distinct advantages. Polyamide thin-film composite (PA-TFC) OSRO membranes have recently emerged as promising alternatives for this purpose. However, the development of PA-TFC membranes for OSRO remains in its early stages. It is highly desirable to improve the membrane performance to achieve high permeance and selectivity. Herein, we proposed a temperature-assisted method of modulating the performance of a PA-TFC membrane supported by an organic solvent-resistant polyketone substrate for OSRO. For the first time, we investigated the combined effect of an aqueous solution and the reaction circumstance temperature on the formation of the PA layer. These conditions were correlated with the resultant membrane morphology and structure. With increasing temperature, the synergistic effect of the increased reaction kinetics and enhanced IP instabilities induced changes in the structural parameters of the PA layer. By analyzing the evolution of these parameters, including the density of the leaf-like nanostructure and size on the membrane surface, thickness of the PA film (wall of surface nanostructures) and layer, surface roughness, and crosslinking, we proposed a mechanism for modulating the PA-TFC membrane by tuning the temperature. Structural modulation of PA also led to a change in the OSRO performance. In methanol/toluene (90/10, wt) separation, the membranes fabricated at temperatures of 70 and 90 °C displayed competitive performance compared to the results of peer research. This study advances the evolution of PA-TFC membranes in terms of OSRO performance.

Janus-inspired flexible cellulose nanofiber-assisted MXene/Silver nanowire papers with fascinating mechanical properties for efficient electromagnetic interference shielding

MXene-based nanocomposites are highly desirable for electromagnetic interference (EMI) shielding applications. However, it is crucial but challenging to obtain an excellent trade-off between mechanical properties and EMI performances. Herein, inspired by Janus structure, flexible cellulose nanofiber-assisted MXene/silver nanowires (CNF-MXene/AgNWs) papers (CMAPs) are developed by a scalable sequential self-assembly plus a hot-pressing strategy. The ingenious introduction of highly conductive AgNWs into MXene forms a complementary leaf-like nanostructure, synergistically constructing highly effective conductive frameworks. Contributed by the designed Janus architecture, high-performance CNF substrate, and extensive hydrogen-bonding interactions, the resultant Janus CMAPs (J-CMAPs) with a low MXene/AgNWs addition of 30 wt% possess a high electrical conductivity (1066.85 S/cm), excellent mechanical strength (224.04 MPa) and modulus (9.98 GPa), exceptional EMI shielding effectiveness of 43.65 dB, and record-high EMI SE/t of 16788.51 dB cm−1 and SSE/t of 10543.18 dB cm2 g−1 with a reflection-dominant shielding mechanism, successfully achieving an outstanding balance between mechanical properties and EMI shielding performances. More importantly, high frequency structure simulator (HFSS) simulation in the frequency domain is further conducted to intuitively comprehend the attenuation process of electromagnetic waves and shield mechanism, verifying fascinating EMI shielding performances. Besides, the Janus paper also presents desirable Joule heating performances at low input voltage, short response time (<10 s), and superb heating stability and long-term steady reliability. We believe that the J-CMAPs demonstrate the great potential and advantage for advanced EMI shielding and portable thermal management applications.

Tunable and high-performance self-powered ultraviolet detectors using leaf-like nanostructural arrays in ternary tin zinc sulfide system

Recently, self-powered ultraviolet (UV) detectors have received increasing attention for developing the future demands for optoelectronic devices due to their distinguished photoresponse properties. In this study, an emerging type of self-powered UV detectors using the ternary SnxZn1-xS alloy thin films (0.20 ≤ x ≤ 0.40 mol) were fabricated using the solvothermal process. The structural study showed the formation of two distinct phases of ZnS and SnS for the samples with high content Sn2+ ions. According to the ideal crystal-growth mechanism proposed by periodic bond chain theory, a morphological evolution from nanorods to nanoflakes and unique aligned three-dimensional leaf-like nanostructures was achieved by enhancing the Sn2+ content up to the maximum value of 0.40 mol. The optical properties featured the less influence of band tailing on the band gap energy at the high concentration of Sn2+ ions, resulting in the widening of the band gap energy up to 4.56 eV thanks to the Burstein-Moss effect. From the photosensing measurements, the Schottky barrier heights of the devices were found to significantly reduce under UVB exposure as the Sn2+ content increases, confirming a high Ion/Ioff ratio (>103) for the devices. The UV detectors exhibited superior self-powered characteristics under UVB illumination, having high photosensitivity and fast photoswitching response times (τr = 1.9 and τd = 2.6 ms) at zero voltage. Interestingly, the photoresponse performance of UV detectors can be adjusted by varying the content of Sn2+ ions, which signifies that tunable self-powered UV detectors can be designed by varying the Sn2+ concentration in the ternary SnxZn1-xS system.

A Unique Bamboo Leaf-Like Nanostructure Based Gas Sensor and Its Potential Application in Indoor Formaldehyde Monitor

Indoor air is significant for human health, and formaldehyde (HCHO) is deemed as the major pollutant in indoor environment. Therefore, the effective detection of HCHO has aroused widespread concern increasingly. In this work, a unique bamboo leaf-like sensing material assembled by nanorods was reported and investigated their potential application in HCHO sensing. It was found that the size of nanorod which was acted as the basic unit of the bamboo leaf-like architecture could be controlled via changing the synthesis temperature. The sensing results demonstrated that the bamboo leaf-like architectures with smaller nanorods in diameter exhibited better HCHO gas response which might be attributed to the smaller size and could offer more surface adsorption sites for HCHO and oxygen molecules.

Chemically Coupled Multiwall Carbon Nanotubes with Leaf-Like Nanostructures of NiO for Sensitive and Selective Determination of Uric Acid

The chemical coupling of NiO nanostructures with thermally treated multiwall carbon nanotubes (MWCNTs) is not reported as it provides an enhanced dispersion of composite material in water. The dispersion of MWCNTs has been considered a big challenge. For this purpose, we first thermally treated MWCNTs at 1000°C in air for 30 min. Then, thermally treated MWCNTs were chemically coupled with NiO nanostructures by a hydrothermal method. The material characterization in terms of structure, morphology, and composition is well studied by different analytical techniques. The NiO composite (sample 2) with highest weight of MWCNTs had a leaf-like morphology and it exhibits a cubic phase of NiO. Cyclic voltammetry (CV) was used to study the electrochemical activity of prepared composite material towards the oxidation of uric acid in the phosphate buffer solution of pH 7.0. Sample 2 showed a well-behaved anodic peak with enhanced peak current and exhibited a linear range from 0.01 mM to 2.5 mM for uric acid with a low limit of detection 0.001mM. Sample 2 was found to be very selective under the environment of competing interferents such as urea, glucose, lactic acid and ethanol. This sample exhibits significant stability, thus it is a potential protocol for the monitoring of uric acid from real samples. This study provides a low-cost platform for the fabrication of efficient materials for various applications such as batteries, fuel cells and water splitting.

Study of solvent variation on controlled synthesis of different nanostructured NiCo2O4 thin films for supercapacitive application

The present investigation deals with controlled synthesis of nanostructured NiCo2O4 thin films directly on stainless steel substrates by facile and economical chemical bath deposition technique, without adding a surfactant or a binder. The consequences of different compositions of solvents on morphological and electrochemical properties have been studied systematically. We used different solvent composition as Double Distilled Water (DDW), DDW:Ethanol (1:1) and DDW: N, N dimethylformamide (1:1). The films have been named as NCO-W for DDW, NCO-WE for DDW: Ethanol (1:1) solvent and NCO-WD for DDW: N, N dimethylformamide (1:1) solvent. The morphologies of NiCo2O4 thin films modify substantially with change in a solvent. NCO-W exhibited the spikes of Crossandra infundibuliformis like nanostructures. The NCO-WE favored the formation of uniformly distributed leaf-like nanostructure whereas NCO-WD showed randomly oriented nanoplates all over the surface area. The Electrochemical performance of these NiCo2O4 thin films were studied using cyclic voltammetry, chronopotentiometry, and electrochemical impedance spectroscopy techniques. The NCO-W, NCO-WE and NCO-WD electrodes showed specific capacitance values of 271, 553 and 140 F/g respectively at the current density of 0.5 mA/cm2 and excellent capacitance retention of 90%, 91% and 80% after 2000 cycles for NCO-W, NCO-WE and NCO-WD samples respectively. This result reveals that NiCo2O4 is a prominent electrode material for supercapacitor application.

High-Performance Zwitterionic Nanofiltration Membranes Fabricated via Microwave-Assisted Grafting of Betaine.

The thin-film composite (TFC) nanofiltration (NF) membrane is a very important method in solving the water crisis. However, the fabrication and industrialization of high-performance NF membranes still remains challenging. In this work, zwitterionic NF membranes via microwave-assisted grafting of betaine was first proposed. The resulting polyamide layer showed leaflike nanostructures after modification. Because of the enlarged permeation area and enhanced hydrophilicity derived from the unique leaflike structure, the optimal membrane permeability reached 40.8 L m-1 h-1 bar-1. This water permeance was 2.2 times as high as the original polypiperazine-amide membrane, with a Na2SO4 rejection maintained at 97.0%. More importantly, the membrane demonstrated excellent selectivity to monovalent and divalent anions. This zwitterionic membrane fabricated by microwave-assisted grafting of betaine provides new insight for industrial scalable NF membranes with great potentials.

Construction of hierarchical trimetallic organic framework leaf-like nanostructures derived from carbon nanotubes for gas-sensing applications

Unique trimetallic organic material (TMOM)-based nanostructures combined with the new architectures of metal–organic frameworks (MOFs) are promising candidates for gas-sensing applications. This work is the first to successfully convert MOF nanomaterials into nano-porous carbon through carbon nanotubes (CNT) catalytic reaction via a simple and facile hydrothermal method. The leaf-like nanostructures exhibit a high surface-to-volume ratio of 363 m2 g−1. The TMOM nanostructures were subsequently exposed to different types of target gases for a wide range of gas concentrations at different operating temperatures. The carbon nanotubes (TMOM-CNT) hybrid nanocomposites were characterized using X-ray powder diffraction, X-ray photoelectron spectroscopy, Brunauer–Emmett–Teller, scanning electron microscopy, energy dispersion spectrum analysis, thermo-gravimetric analysis, and transmission electron microscopy. The fabricated Zn-Co-Ni MOF@CNT sensors exhibit high selectivity and gas-sensing response toward H2S gas at an optimal temperature of 325 °C for 100 ppm. These superior gas-sensing performances reveal that the Zn-Co-Ni MOF@CNT sensors with a unique leaf shape exhibit potential applications for the environment applications in gas sensor industry.

Rational design of 2D super holey metal carboniride leaf-like nanostructure for efficient oxygen electrocatalysis

Highly porous and hollow non-noble metal carbonitride nanostructures featuring large surface area and active metal sites are ideal materials for energy conversion. Nevertheless, it remains challenge to synthesize such elegant architectures, since during the carbonization process, the metal clusters aggregation, shape fusion, and pore collapse normally restrict the formation of continuous yet hierarchical porosity, thereby limiting further electrochemical features. Here, we innovatively present a facial alternant two-dimensional (2D) metal-organic frameworks (MOFs) assembly strategy to rationally synthesize a super holey, hollow and shape well-defined Co-N-C nanoleaf (HP-CoNC-L). As a result, despite metal moiety doping, the hierarchal macro-/meso-/micropores interconnected hollow “nanoleaf” evolved both an extra high surface area (1380 m2 g−1) and total pore volume (1.68 cm3 g−1), over two-fold greater than currently reported Co-N-C species. In addition to the hollow structure and fascinating porous network, the intensive Co nanoparticles and abundant active sites jointly contributed to the extraordinary bifunctional catalytic reactivity towards oxygen, e.g. a small ORR/OER subtraction (ΔE = 0.64 V), hence validating the practicability of rechargeable all solid planar micro metal-air batteries.

Dimensional stability of lotus leaf-like nanostructure superhydrophobic bamboo by modification using xylan

Xylan extracted from corncobs was used to modify bamboo and to improve its dimensional stability. A lotus leaf-like surface was prepared on the modified bamboo using a fresh lotus leaf and polydimethylsiloxane (PDMS) as the template and seal via soft lithography. The dimensional stability of bamboo was tested via anti-shrinkage efficiency (ASE), moisture excluding efficiency (MEE), weight percent gain (WPG), and its superhydrophobic property. The microstructures of lotus-like bamboo surface were analyzed via water contact angle (WCA), scanning electron microscopy, and atomic force microscopy (AFM). The study found that with increasing mass fraction of xylan content, the anti-swelling property and WPG of modified bamboo increased accordingly. When the mass fraction of xylan was 10%, its WPG was the largest (2.21%), and xylan had a better compatibilization effect on bamboo. The dimensional stability of bamboo was improved to a certain extent by xylan. Moreover, the anisotropy and superhydrophobicity of the lotus leaf-like bamboo treated by xylan were noticeably improved after modification, such that the WCA of the transverse, radial, and tangential sections were 157.5º, 145.5º, and 137.5º, respectively. This research lays a foundation for studies of dimensional stability of bamboo and the mechanism of modification to achieve hydrophobic properties.

Mo Doped Amorphous CoSx Porous Leaf-Like Nanostructure on Ti Mesh as Electrocatalyst for Alkaline Hydrogen Production

Reducing water dissociation barrier and then expediting its kinetics are of great significance to enhance alkaline water splitting for hydrogen evolution. Herein, Mo doped CoSx on Ti mesh (defined as Mo doped CoSx/TM) was synthesized by multistep pathways using Co-MOF as precursor. The characterization results confirmed the amorphous structure and porous leaf-like morphology of Mo doped CoSx. The alkaline HER measurement indicated Mo doped CoSx/TM exhibited the enhanced HER performance with overpotential (η) of 230 mV at −10 mA cm−2, lower than that of Co3S4/TM (265 mV) and other samples (>350 mV), and reduced Tafel slope (98.3 mV dec−1), as well as decent stability. The lowest Tafel slope meant the highest water dissociation kinetics and the reaction followed Volmer-Heyrovsky mechanism over Mo doped CoSx/TM. The excellent alkaline HER performance of Mo doped CoSx/TM was due to the increased intrinsic activity caused by cooperative effect between Mo and CoSx, and the porous leaf-like structure, which was in favor of exposing much more accessible active sites and facilitating mass transfer. This work demonstrates the validity of Mo doping in promoting HER performance of cobalt sulfide, which offers a strategy to design highly efficient transition metal chalcogenides for catalysis and energy conversion.

Boosting ion dynamics through superwettable leaf-like film based on porous g-C3N4 nanosheets for ionogel supercapacitors

Ionic liquid (IL) electrolytes have enormous potential for the development of high energy density supercapacitors (SCs) owing to their wide potential windows, but ILs are plagued by sluggish ionic diffusion due to their high viscosity and large ion size. Exploiting superwettable electrodes possessing high compatibility with IL electrolytes remains challenging. Inspired by the biological characteristics observed in nature, a unique film electrode with a Monstera leaf-like nanostructure is synthesized and used to overcome the aforementioned bottleneck. Similar to the pores in Monstera leaves that allow the permeation of air and water vapor, the film electrode is based on porous g-C3N4 nanosheets (~1 nm thick) as ion-accessible “highway” channels, allowing ultrafast diffusion of IL ions. The film exhibits a high diffusion coefficient (3.68 × 10−10 m2 s−1), low activation energy (0.078 mJ mol−1) and extraordinary wettability in the IL electrolyte, indicating its superior IL ion dynamics. As a proof of concept, flexible ionogel SCs (FISCs) with tailorability and editability are fabricated, which exhibit a high energy density (10.5 mWh cm−3), high-power density, remarkable rate capability, and long-term durability, outperforming previously reported FISCs. Importantly, these FISCs can be effectively charged by harvesting sustainable power sources, particularly the rarely studied wind power, for practical applications.

Highly Cation Permselective Metal-Organic Framework Membranes with Leaf-Like Morphology.

Highly cation permselective metal-organic framework (MOF) membranes are desirable for the extraction of valuable metal cations. However, fabrication of defect-free and stable permselective MOF membranes is technically challenging, owing to their arduous self-assembly and poor water resistance, respectively. A simple and readily scalable method has been developed for the controlled in situ smart growth of UiO-66-NH2 into leaf-like nanostructures with tunable density of the leaves and the surface layer thickness. The self-assembly approach reproducibly fabricates seamless, ultrathin (<500 nm) UiO-66-NH2 membranes at the surface of anodic aluminum oxide. The membranes contain nanosized interstices among the MOF leaves, which enable maximum admission of ions within the membrane, and angstrom-sized inherent pores in every single UiO-66-NH2 crystal, which efficiently regulate the cation permselectivity. Consequently, the highest ever reported cation separations (Na+ /Mg2+ >200 and Li+ /Mg2+ >60) and excellent membrane stability during five sequential electrodialysis cycles are achieved. These characteristics position the fabricated MOF membranes as potential candidates for efficient extraction of pure lithium and sodium ions from salt lakes and seawater, respectively.

Construction of a highly efficient near-IR solid emitter based on naphthalene diimide with AIE-active tetraphenylethene periphery

AIE-active TTPEcNDI shows distinct near-IR optical properties and self-assembles into hollow spheres, fibrils and leaf-like nanostructures via solvophobic control.

Novel BiVO4/InVO4 heterojunctions: Facile synthesis and efficient visible-light photocatalytic performance for the degradation of rhodamine B

In this work, novel visible-light-driven BiVO4/InVO4 composite photocatalysts were fabricated by a facile hydrothermal method. The XRD results indicated that the prepared photocatalyst is a two-phase composite of BiVO4 and InVO4. SEM results illustrated that with the increase of BiVO4 content the morphology of BiVO4/InVO4 composites changed from hierarchical microsphere to leaf-like nanostructure. The photocatalytic activities of the as-synthesized samples were evaluated towards the degradation of rhodamine B (Rh B) aqueous solution. The results showed that the as-fabricated BiVO4/InVO4 photocatalysts displayed much higher photocatalytic activities in comparison with pure InVO4. The BiVO4/InVO4 composite with a BiVO4 content of 80wt% exhibited the highest photocatalytic performance. The enhanced photocatalytic activity of the BiVO4/InVO4 composite photocatalyst was attributed predominantly to the efficient separation of photoinduced electrons and holes because of the heterojunction formed between BiVO4 and InVO4. The possible photocatalytic mechanism of BiVO4/InVO4 composite was also discussed in detail. Superoxide radicals were the major active species.

On the thermal growth and properties of doped TiO2 and In2O3 elongated nanostructures and nanoplates

In this work, the driving forces behind the growth mechanisms of In2O3 and TiO2 micro- and nano-structures grown by an evaporation–solidification method are discussed. Effective or limited doping incorporation and its influence on the growth and morphology of the low dimensional structures are also assessed. A dislocation driven growth mechanism is proposed for indium oxide, indium tin oxide (ITO) and zinc doped indium oxide (IZO) nanowires. This growth mechanism is extended to the growth of IZO nano-plates. On the other hand, different low dimensional TiO2 morphologies, mainly nanowires, needles, and bidimensional leaf-like nanostructures, have been obtained by an anisotropic induced growth. By introducing Cr in the precursor mixture, needles are formed showing stepped lateral faces related to oxygen defect stoichiometry areas as observed by EDS mapping.

Surfactant Assisted Synthesis of Copper Oxide (CuO) Leaf-like Nanostructures for Electrochemical Applications

Three different copper oxide (CuO) leaf-like nanostructures have been synthesised by micelles micro emulsion method using a surfactant of copper dodecyl sulphate (Cu(DS)2) by varying the concentration of sodium hydroxide (NaOH). This study was carried out to investigate the effect of NaOH concentration on the stability, crystalline domain and pseudocapacitance behaviour of the leaf-like nanostructures. The samples were characterized by X-ray diffraction (XRD), thermogravimetry analysis (TGA), Raman spectroscopy, Fourier-Transform Infrared (FTIR), scanning electron microscopy (SEM) and Transmission electron microscopy (TEM). It was observed that the crystalline domain size (12 nm-18 nm) and size distribution of the as-synthesized nanocrystals decreases with increasing concentration of NaOH. The interactions mechanism and formation of the leaf-like structure have been elucidated and correlated with various analytical techniques. The domain size and NaOH concentration tend to influence the charge transfer resistance.

Synthesis and Characterization of Leaf-Like CuO Nanostructures

Synthesis and Characterization of Leaf-Like CuO Nanostructures