Nanowall Arrays Research Articles

Interlayer Space Engineering-Induced Pseudocapacitive Zinc-Ion Storage in Holey Graphene Oxide-Bearing Vertically Oriented MoS2 Nano-Wall Array Cathode for Aqueous Rechargeable Zn Metal Batteries.

Transition metal dichalcogenides, particularly MoS2, are acknowledged as a promising cathode material for aqueous rechargeable zinc metal batteries (ARZMBs). Nevertheless, its lack of hydrophilicity, poor electrical conductivity, significant restacking, and restricted interlayer spacing translate into inadequate capacity and rate performance. Herein, the unique porous structure and additional functional groups present in holey graphene oxide (hGO) are taken advantage of to dictate the vertical growth pattern of oxygen-doped MoS2 nanowalls (O-MoS2/NW) over the hGO surface. Compared to conventional graphene oxide (GO), the presence of nano-pores in hGO facilitates the homogeneous dispersion of Mo precursors and provides stronger interaction sites, promoting the uniform vertical alignment of O-MoS2/NW. The synergistic interaction between O-MoS2-NW and hGO translates to enhanced electron conductivity, efficient electrolyte penetration, enhanced interlayer spacing, reduced restacking, and enhanced surface area. As a consequence of precise control of various factors that decide the overall battery performance, a high discharge capacity (227mAhg-1 at 100mAg-1) cathode material with significantly lower charge transfer resistance (66Ω) compared to pristine O-MoS2 (153Ω) is developed. These findings underscore the potential of hGO as a multifunctional platform for nanoengineering high-performance cathode materials for the next generation of efficient and durable ARZMBs.

Rational Construction of 3D Self-Supported MOF-Derived Cobalt Phosphide-Based Hollow Nanowall Arrays for Efficient Overall Water Splitting At large Current Density.

Developing efficient nonprecious bifunctional electrocatalysts for hydrogen and oxygen evolution reactions (HER and OER) in the same electrolyte with a low overpotential and large current density presents an appealing yet challenging goal for large-scale water electrolysis. Herein, a unique 3D self-branched hierarchical nanostructure composed of ultra-small cobalt phosphide (CoP) nanoparticles embedded into N, P-codoped carbon nanotubes knitted hollow nanowall arrays (CoPʘNPCNTs HNWAs) on carbon textiles (CTs) through a carbonization-phosphatization process is presented. Benefiting from the uniform protrusion distributions of CoP nanoparticles, the optimum CoPʘNPCNTs HNWAs composites with high abundant porosity exhibit superior electrocatalytic activity and excellent stability for OER in alkaline conditions, as well as for HER in both acidic and alkaline electrolytes, even under large current densities. Furthermore, the assembled CoPʘNPCNTs/CTs||CoPʘNPCNTs/CTs electrolyzer demonstrates exceptional performance, requiring an ultralow cell voltage of 1.50V to deliver the current density of 10mAcm-2 for overall water splitting (OWS) with favorable stability, even achieving a large current density of 200mAcm-2 at a low cell voltage of 1.78V. Density functional theory (DFT) calculation further reveals that all the C atoms between N and P atoms in CoPʘNPCNTs/CTs act as the most efficient active sites, significantly enhancing the electrocatalytic properties. This strategy, utilizing 2D MOF arrays as a structural and compositional material to create multifunctional composites/hybrids, opens new avenues for the exploration of highly efficient and robust non-noble-metal catalysts for energy-conversion reactions.

Design of graphene-like nanowall arrays and their optical absorption properties

Design of graphene-like nanowall arrays and their optical absorption properties

Unique hierarchical architecture of SnO2 hexagonal interconnected nanolayered arrays as negative electrode for high performance asymmetric supercapacitors

In this research, we report unique hierarchical structures of SnO2 hexagonal interconnected nanolayered arrays (HINLA) fabricated on the carbon cloth (SnO2 HINLA@CC) by a facile electrochemical deposition technique. The structural, morphological evolution and electrochemical properties of as prepared SnO2 HINLA@CC are explored as negative electrode of SCs. SnO2 HINLA@CC has been tested in negative potential widow of −1.0-0 V and demonstrated the high specific capacitance of 325 F g−1 at 1 A g−1, much superior when compared to the previously reported data for SnO2. The EIS analysis confirmed the charge transfer kinetics of SnO2 HINLA@CC, with significant stability due to favorable morphology for swift response. Capacitance retention plot confirmed no structural degradation or pulverization for negative electrode even after 5000 galvanostatic charge with 88.6% capacitance retention. Such high performances of SnO2 HINLA@CC as negative electrode make it an ideal candidate to be useful in ASCs. Moreover, a 2.2 V aqueous ASC has been constructed by employing Na0·5MnO2 nanowall arrays (NWAs) as cathode and SnO2 HINLA@CC as anode. In particular, the 2.2 V Na0·5MnO2 NWAs@CC//SnO2 HINLA@CC ASC has demonstrated the superior energy density of ∼73 Wh kg−1, significant rate capability and excellent cycling ability, outperforming the previously reported SnO2-based ASCs. Present work provides new opportunities for developing promising high-voltage aqueous ASCs with excellent energy density.

Nanoflowers-like LiTi2(PO4)3 on carbon nanotube fibers as novel binder-free anodes for high-performance fiber-shaped aqueous rechargeable lithium-ion batteries

NASICON-type LiTi2(PO4)3 (LTP) shows tremendous potential for applications in aqueous rechargeable lithium-ion batteries (ARLIBs) due to its three-dimensional open-framework and flat voltage platform. Unfortunately, conventional solid-phase reactions and high-temperature calcination methods are unable to meet the demand for self-standing electrodes for flexible wearable ARLIBs. Herein, we develop a simple and effective one-step solvothermal method to grow nanoflowers (NFs)-like LTP directly on carbon nanotube fibers (CNTFs) as binder-free anodes for fiber-shaped ARLIBs (FARLIBs) without additional high-temperature treatment. Benefitting from the robust adhesion of the active material to the substrate and binder-free feature, the prepared LTP NFs/CNTF anode provides a high reversible volume capacity of 85.2 mAh cm−3 at a current density of 0.4 A cm−3. The quasi-solid-state FARLIB is successfully assembled by binder-free cathode coupling with LiMn2O4 nanowall arrays directly grown on CNTF, achieving a high capacity of 58.3 mAh cm−3 at a current density of 0.4 A cm−3 and exhibiting an encouraging 92.3 mWh cm−3 maximum energy density. This work provides an effective strategy for the design of novel binder-free electrodes for next-generation wearable FARLIBs.

Boosting Li‐Ion Storage Capability of Self‐Standing Ni‐Doped LiMn2O4 Nanowall Arrays as Superior Cathodes for High‐Performance Flexible Aqueous Rechargeable Li‐Ions Batteries

AbstractTo meet the increasing desire for a means of powering wearable and portable devices, the development of high‐performance flexible aqueous rechargeable lithium‐ion batteries (FARLIBs) would be greatly desirable. The design of binder‐free cathode materials with 3D architectures is the key to develop FARLIBs. Herein, self‐standing 3D Ni‐doped LiMn2O4 (NLMO) nanosheets are successfully prepared assembled by nanowall arrays (NWAs) directly grown on carbon cloth (CC) as the cathode for LIBs, which is performed to slow down the dissolution of Mn and the Jahn–Teller effect of LiMn2O4 during the reaction process. The as‐prepared NLMO NWAs/CC electrode delivers a high capacity of 113.27 mAh g−1 at a current density of 1 A g−1, and can also have a capacity retention rate of 81% after 500 cycles at 10 A g−1, both higher than that of pure LiMn2O4. The results of density functional theory simulation demonstrate that the Ni‐doped LiMn2O4 can significantly decrease the bandgap and Li ions diffusion barriers. A quasi‐solid‐state FARLIB is successfully constructed by using NLMO NWAs/CC as the positive electrode and rugby‐shaped NaTi2(PO4)3/CC as the negative electrode, exhibiting remarkable electrochemical performance and flexibility. These results offer a new opportunity for developing high‐performance FARLIB.

Rational Design of Porous Nanowall Arrays of Ultrafine Co4N Nanoparticles Confined in a La2O2CN2 Matrix on Carbon Cloth for a High-Performing Supercapacitor Electrode.

Transition metal nitrides (TMNs) have received special concern as important energy storage materials, owing to their high conductibility, good mechanical strength, and superior corrosion resistance. However, their insufficient capacitance and poor cycling stability limit their practical applications for supercapacitors. Here, a novel three-dimensional (3D) self-supported integrated electrode consisted of porous nanowall arrays of ultrafine cobalt nitride (Co4N) nanoparticles encapsulated in a lanthanum oxycyanamide (LOC) matrix on carbon cloth (Co4N@LOC/CC) for outstanding electrochemical energy storage is rationally designed and fabricated. The 3D monolithic configuration of porous nanowall arrays facilitates the mass/charge transfer, the exposure of electroactive sites, and the enhancement of electrical conductivity. Meanwhile, the unique core-shell structure of Co4N@LOC can prevent ultrafine Co4N nanoparticles from sintering, agglomeration, and oxidation and promotes electron transfer dynamics during the redox reaction, meanwhile enhancing the stability of the electrode. Additionally, the synergy of Co4N and LOC can result in an efficient electron/ion transport in the process of the charge-discharge. Because of these features, the Co4N@LOC/CC electrode displays superior specific capacitance (895.6 mF cm-2 or 613.4 F g-1 at 1 mA cm-2) and admirable cycling durability (87.9% capacitance reservation after 10 000 cycles), surpassing the majority of nitride-based electrodes reported thus far. Furthermore, after being assembled into an asymmetric supercapacitor using active carbon (AC) as an anode, the obtained Co4N@LOC/CC//AC/CC device displays a high energy density of 41.7 Wh kg-1 at the power density of 875.8 W kg-1 with a high capacitance reservation of 87.6% after 5000 cycles at 2 mA cm-2. This work offers an efficient approach of combining TMNs with rare earth compounds to enhance the capacitance and stability of TMNs for supercapacitor electrodes.

Homogeneously distributed heterostructured interfaces in rice panicle-like SbBi-Bi2Se3-Sb2Se3 nanowalls for robust sodium storage

Antimony-based materials offer great potential for sodium-ion battery application owing to their high capacity and suitable Na alloying potential. However, their practical application is hampered by the rapid capacity decay resulting from serious volume change during cycling. Herein, we report a template-free electrodeposition method to grow SbBi-Bi2Se3-Sb2Se3 (SbBi-Se) self-supported nanowall array with a rice-panicle-like top surface directly on Cu substrates. During the electrodeposition, Bi, Sb, and Se have been simultaneously incorporated into the nanowalls, giving rise to an array structure with uniformly dispersed phases of SbBi alloy, and metal selenides Bi2Se3 and Sb2Se3. As a result, the heterostructured interfaces amongst these phases are also homogeneously distributed throughout the entire structure. The density functional theory calculation results indicate that these interfaces facilitate Na+ diffusion and promote electronic conduction, and the sample also demonstrates enhanced high-rate performance and superior cyclic retention with almost no capacity decay after 100 cycles at 0.7 A/g. More importantly, in-situ temperature sensing suggests that such a unique heterostructured material exhibits high thermal stability during charge/discharge, while ex-situ analysis confirms that this electrode material induces the formation of a highly stable SEI film, and verifies the high durability of these alloy and selenide phases allowing the interfaces to keep functioning during charge/discharge process.

High-Performance flexible Quasi-Solid-State aqueous Nickel-Iron battery enabled by MOF-Derived N-Doped carbon hollow nanowall arrays

The development of portable, flexible and wearable electronic devices has accelerated ever-growing demand for high-performance power sources with high specific energy/power density, high-level safety, low cost, and highly flexible features. Herein, a flexible quasi-solid-state aqueous nickel–iron (QSSA Ni-Fe) battery with high energy and power densities is rationally developed using ultrathin Ni(OH)2 nanoflakes and porous ɑ-Fe2O3 nanorods conformally deposited on vertically aligned MOF-derived N-doped carbon hollow nanowalls supported by carbon textiles (NC/CTs) as the cathode (Ni(OH)2@NC/CTs) and anode (ɑ-Fe2O3@NC/CTs), respectively. The obtained flexible QSSA Ni-Fe battery delivers optimal electrochemical performance, including high energy density (155.4 Wh Kg−1), high power density (14.0 KW Kg−1) and excellent cycling stability (∼86.1 % retention after 10,000 cycles). Impressively, the flexible QSSA Ni-Fe battery delivers stable electrochemical performance even under different bending conditions. The excellent electrochemical properties may be attributed to the following reasons: (i) The ultrathin Ni(OH)2 nanoflakes and porous ɑ-Fe2O3 nanorods deposited on 2D hollow NC arrays possess a high porosity and large specific surface area; (ii) The 2D hollow NC arrays on flexible CTs not only increase the electrical conductivity, but also function as a scaffold to hold the active materials (such as Ni(OH)2 or ɑ-Fe2O3) and thus maintain the structural integrity of the composites. This work provides a novel approach to design and develop QSSA batteries with satisfactory electrochemical properties and excellent flexibility, and have greater potential for future flexible and wearable electronic devices.

Preparation of self-healing Ni-Al layered double hydroxide superhydrophobic coating with nanowall arrays on aluminum alloy

The existence of self-healing performance can effectively improve the service life of superhydrophobic coating. Due to its unique chemical composition and microstructure, layered double hydroxide (LDH) material is an ideal material for preparing self-healing superhydrophobic coatings. In this research, a Ni-Al LDH superhydrophobic coating with self-healing performance was prepared on aluminum alloy 6061 by hydrothermal reaction and low energy modification. The effects of hydrothermal parameters on the microstructure and wettability of the coating were investigated. The prepared coating with nanowall arrays showed excellent superhydrophobicity with contact angle of 162.1 ± 0.4° and rolling angle of 1.9 ± 0.3°. The superhydrophobic coating exhibited excellent low adhesion and self-cleaning properties, and could effectively improve the corrosion resistance of aluminum alloy. In addition, the coating showed good stability in different harsh environments, and could self-heal quickly under the thermal stimulation after losing superhydrophobicity.

Pitch‐black surface stemming from self‐standing ZnFe2O4 nanowalls

AbstractCombinations of surface nanostructures with the intrinsic photo‐interactivity of constituent materials could enhance photoabsorption properties. Although the intrinsic photoabsorption properties of ZnFe2O4 in a broad wavelength range have been reported, the photoabsorption properties of ZnFe2O4 with surface nanostructures have not been investigated yet. In this study, a pitch‐black surface, which is covered with a ZnFe2O4 nanowall array, is generated via a facile synthesis method, that is, heating a pre‐electrodeposited surface layer comprising Zn and Fe in air. The key factors for generating the nanowall array are the Zn content in the pre‐electrodeposited ZnFe layer and the heating temperature. The generation mechanism of the nanowall array is proposed based on the thermodynamics of oxides and the dynamics of crystal growth. The black surface absorbs greater than 94% and 97% of the incident light over wavelength ranges of 200–2500 nm and 200–1100 nm, respectively. Surfaces with the ZnFe2O4 nanowall array are promising for various optical, environmental and energy applications owing to their unique nanostructure and the intrinsic functional properties of ZnFe2O4.

High-Performance Flexible Quasi-Solid-State Aqueous Nickel-Iron Battery Enabled by Mof-Derived N-Doped Carbon Hollow Nanowall Arrays

High-Performance Flexible Quasi-Solid-State Aqueous Nickel-Iron Battery Enabled by Mof-Derived N-Doped Carbon Hollow Nanowall Arrays

Template-free formation of oriented oxide nanowalls via topotactic-like pseudomorphic transformation: [110]-MgO(111) nanowall arrays

The template-free formation of oriented MgO nanowall arrays is successfully achieved by a two-step synthesis route of (i) electrodeposition of vertically aligned hydroxide and (ii) its topotactic-like pseudomorphic transformation to oxide.

Microfluidic Fabrication of Hierarchical‐Ordered ZIF‐L(Zn)@Ti3C2Tx Core–Sheath Fibers for High‐Performance Asymmetric Supercapacitors

AbstractWe report hierarchical‐ordered ZIF−L(Zn)@Ti3C2Tx MXene core–sheath fibers, in which a ZIF−L(Zn) nanowall array sheath is grown vertically on an anisotropic Ti3C2Tx core by Ti−O−Zn/Ti−F−Zn chemical bonds. Through highly efficient microfluidic assembly and microchannel reactions, ZIF−L(Zn)@Ti3C2Tx exhibits well‐developed micro‐/mesoporosity, ordered ionic pathways, fast interfacial electron conduction and large‐scale fabrication, significantly boosting charges dynamic transport and intercalation. The resultant ZIF−L(Zn)@Ti3C2Tx fiber presents large capacitance (1700 F cm−3) and outstanding rate performance in a 1 M H2SO4 electrolyte. Additionally, ZIF−L(Zn)@Ti3C2Tx fiber‐based solid‐state asymmetric supercapacitors deliver high energy density (19.0 mWh cm−3), excellent capacitance (854 F cm−3), large deformable/wearable capabilities and long‐time cyclic stability (20 000 cycles), which realize natural sunlight‐induced self‐powered applications to drive water level/earthquake alarm devices.

Microfluidic Fabrication of Hierarchical-Ordered ZIF-L(Zn)@Ti3 C2 Tx Core-Sheath Fibers for High-Performance Asymmetric Supercapacitors.

We report hierarchical-ordered ZIF-L(Zn)@Ti3 C2 Tx MXene core-sheath fibers, in which a ZIF-L(Zn) nanowall array sheath is grown vertically on an anisotropic Ti3 C2 Tx core by Ti-O-Zn/Ti-F-Zn chemical bonds. Through highly efficient microfluidic assembly and microchannel reactions, ZIF-L(Zn)@Ti3 C2 Tx exhibits well-developed micro-/mesoporosity, ordered ionic pathways, fast interfacial electron conduction and large-scale fabrication, significantly boosting charges dynamic transport and intercalation. The resultant ZIF-L(Zn)@Ti3 C2 Tx fiber presents large capacitance (1700 F cm-3 ) and outstanding rate performance in a 1 M H2 SO4 electrolyte. Additionally, ZIF-L(Zn)@Ti3 C2 Tx fiber-based solid-state asymmetric supercapacitors deliver high energy density (19.0 mWh cm-3 ), excellent capacitance (854 F cm-3 ), large deformable/wearable capabilities and long-time cyclic stability (20 000 cycles), which realize natural sunlight-induced self-powered applications to drive water level/earthquake alarm devices.

Hierarchical Mg-Birnessite Nanowall Arrays with Enriched (010) Planes for High Performance Aqueous Mg-Ion Batteries

Birnessite MnO2 is a promising cathode material for aqueous Mg-ion batteries due to its layered structure with large interlayer distance. However, the two-dimensional growth mode of birnessite induces nanosheet morphology with preferred growth of inactive (001) planes with sluggish ion transport kinetics. In this work, a high Mg content birnessite with hierarchical nanowall arrays morphology is prepared by in situ electro-conversion using spinel Mn3O4 nanowall arrays. The electro-conversion Mg-birnessite (ECMB) nanowall arrays are assembled by ultrasmall nanosheets with reduced (001) planes but increased active (010) planes, affording enriched open intercalation channels and shortened Mg2+ diffusion length. Consequently, the ECMB cathode exhibits a large specific reversible capacity of about 255.1 mAh g−1 at a current density of 200 mA g−1, and outstanding cycling stability with 73.6% capacity retention after 3000 cycles. Finally, a 2.2 V aqueous full cell is constructed by using ECMB as positive electrode and polyimide as negative electrode, which achieves a high energy density of 65.2 Wh kg−1 at a power density of 96 W kg−1. This work demonstrates effective crystal plane modulation for Mg-birnessite to achieve superior Mg2+ storage in aqueous batteries.

Triangle nanowall arrays of ultrathin MoS2 nanosheets vertically grown on Co-Fe bimetallic disulfide as highly efficient electrocatalysts for hydrogen evolution reaction

Hydrogen evolution reaction (HER) in water splitting normally requires efficient and durable electrocatalysts. Herein, we demonstrate Fe-CoS2@MoS2 triangle nanowall arrays grown on carbon cloth (CC) exhibiting superior electrocatalytic performance for HER. In this strategy, CC acts as conductive substrate to generate Co-MOF and Fe is introduced through ligand exchange of [Fe(CN)6]4−, and sulfidation treatment produces the Co-Fe bimetallic disulfide (noted as Fe-CoS2) nanowall arrays, on which vertically oriented MoS2 nanosheets grow via hydrothermal reaction. The as-obtained CC@Fe-CoS2@MoS2 catalyst shows an extremely low overpotential of 68 mV to deliver 10 mA cm−2 current density (η10 = 68 mV) and high stability (24 h) in acid media (0.5 M H2SO4). The vertically growing MoS2 ultrathin nanosheets expose more catalytic active sites. Meanwhile, electron transfer from Co to Mo may result in increased electron density of MoS2 thus enhancing the conductivity. The DFT calculations reveal that the hybridization of MoS2 and Fe-CoS2 dramatically reduces the Gibbs free energy of H adsorption and speeds up HER process. All the above merits contribute to the improved HER performance. This study will provide an inspiration for the design of novel electrocatalysts via interface engineering for scalable hydrogen generation.

Graphdiyne Hybrid Nanowall Arrays for High-capacity Aqueous Rechargeable Zinc Ion Battery

Graphdiyne Hybrid Nanowall Arrays for High-capacity Aqueous Rechargeable Zinc Ion Battery

Modelling the photoemission characteristics of parallel aligned (Al)GaN nanowall arrays assisted by built-in/external field

The photoemission and electron collection properties of nanostructure photoemitter based on parallel aligned (Al)GaN nanowall arrays are investigated. In general, the photoelectric conversion efficiency of intrinsic GaN NWAs exhibit a significant improvement compared with planar photoemitter. Assisted by the built-in field induced by gradient decreasing Al component along axial direction of the nanowall, the proportion of emitting photoelectrons on each surface of a nanowall is redistributed and the collected photocurrent is obviously enhanced yet with a negative effect against quantum efficiency and emitted photocurrent. External field incorporation can tune the electron emitting path and improve the collection efficiency, but accompanied with a further decline in emitting photocurrent and quantum efficiency. For a certain configuration with nanowall height of 1 µm and spacing length of 1 µm, the optimum field intensity for emitting and collected photocurrent are respectively 0.3 and 0.5 V/µm. The alteration of photocurrent varied with field intensity dominated by the photoelectrons from the top surface and irradiated side face of the nanowall.

Bimetallic-MOF-Derived Amorphous Zinc/Cobalt-Iron-Based Hollow Nanowall Arrays via Ion Exchange for Highly Efficient Oxygen Evolution.

Oxygen evolution reaction (OER) is critical for optimizing renewable energy systems, including metal-air batteries and water electrolysis. One major challenge for OER is to develop durable and cost-effective electrocatalysts with high catalytic performance. Herein, a controllable ion-exchange method to synthesize amorphous zinc/cobalt-iron hydroxide-based hollow nanowall arrays (A-Zn/Co-Fe HNAs) derived from bimetallic metal-organic frameworks (MOFs) on carbon cloth is reported. The amorphous characteristic enables the presented materials with more electrocatalytic sites and short diffusion paths for rapid access to the electrolyte, achieving efficient charge transfer for OER. The optimized nanostructure of A-Zn/Co-Fe HNAs via tuning the amount of iron sulfate in the reaction solution delivers a low overpotential of 226mV to reach a current density of 10mA cm-2 with a small Tafel slope of 37.81mV dec-1 while exhibiting high durability at varied current densities over 80 h. The remarkable electrochemical performance can be attributed to the synergistic effect from chemical elements of Zn, Co-Fe, and a robust hollow structure. This simple method of fabricating bimetallic-MOF-derived amorphous Zn/Co-Fe HNAs on carbon cloth can be applied as a practical platform for other OER electrocatalysts.