High Density 3D Carbon Tube Nanoarray Electrode Boosting the Capacitance of Filter Capacitor

Electric double-layer capacitors(EDLCs)with fast frequency response are regarded as small-scale alternatives to the commercial bulky aluminum electrolytic capacitors.Creating carbon-based nanoarray electrodes with precise alignment and smooth ion channels is crucial for enhancing EDLCs’performance.However,controlling the density of macropore-dominated nanoarray electrodes poses challenges in boosting the capacitance of line-filtering EDLCs.Herein,a simple technique to finely adjust the vertical-pore diameter and inter-spacing in three-dimensional nanoporous anodic aluminum oxide(3D-AAO)template is achieved,and 3D compactly arranged carbon tube(3D-CACT)nanoarrays are created as electrodes for symmetrical EDLCs using nanoporous 3D-AAO template-assisted chemical vapor deposition of carbon.The 3D-CACT electrodes demonstrate a high surface area of 253.0 m^(2) g^(−1),a D/G band intensity ratio of 0.94,and a C/O atomic ratio of 8.As a result,the high-density 3D-CT nanoarray-based sandwich-type EDLCs demonstrate a record high specific areal capacitance of 3.23 mF cm^(-2) at 120 Hz and exceptional fast frequency response due to the vertically aligned and highly ordered nanoarray of closely packed CT units.The 3D-CT nanoarray electrode-based EDLCs could serve as line filters in integrated circuits,aiding power system miniaturization.

Self-Powered Piezo-Supercapacitors Based on ZnO@Mo-Fe-MnO_(2)Nanoarrays

The development of self-charging supercapacitor power cells(SCSPCs)has profound implications for smart electronic devices used in different fields.Here,we epitaxially electrodeposited Mo-and Fe-codoped MnO_(2)films on piezoelectric ZnO nanoarrays(NAs)grown on the flexible carbon cloth(denoted ZnO@Mo-Fe-MnO_(2)NAs).A self-charging supercapacitor power cell device was assembled with the Mo-and Fe-codoped MnO_(2)nanoarray electrode and poly(vinylidenefluoride-co-trifluoroethylene)(PVDF-Trfe)piezoelectric film doped with BaTiO_(3)(BTO)and carbon nanotubes(CNTs)(denoted PVDF-Trfe/CNTs/BTO).The self-charging supercapacitor power cell device exhibited an energy density of 30μWh cm^(-2)with a high power density of 40 mW cm^(-2)and delivered an excellent self-charging performance of 363 mV(10 N)driven by both the piezoelectric ZnO nanoarrays and the poly(vinylidenefluoride-co-trifluoroethylene)piezoelectric film doped with BaTiO_(3)and carbon nanotubes.More intriguingly,the device could also be self-charged by 184 mV due to residual stress alone and showed excellent energy conversion efficiency and low self-discharge rate.This work illustrates for the first time the self-charging mechanism involving electrolyte ion migration driven by both electrodes and films.A comprehensive analysis strongly confirmed the important contribution of the piezoelectric ZnO nanoarrays in the self-charging process of the self-charging supercapacitor power cell device.This work provides novel directions and insights for the development of selfcharging supercapacitor power cells.

ZnO@MOF@PANI core-shell nanoarrays on carbon cloth for high-performance supercapacitor electrodes

Hierarchical ZnO@metal-organic framework @polyaniline(ZnO@MOF@PANI) core-shell nanorod arrays on carbon cloth has been fabricated by combining electrodeposition and hydrothermal method. Well-ordered Zn O nanorods not only act as a scaffold for growth of MOF/PANI shell but also as Zn source for the formation of MOF. The morphology of ZnO@MOF@PANI composite is greatly influenced by the number of PANI electrodeposition cycles. Their structural and electrochemical properties were characterized with different techniques. The results indicate that the Zn O@MOF@PANI with 13 CV cycles of PANI deposition demonstrates the maximum specific capacitance of 340.7 F g-1 at 1.0 A g-1, good rate capability with84.3% capacitance retention from 1.0 to 10 A g-1 and excellent cycling life of 82.5% capacitance retention after 5000 cycles at high current density of 2.0 A g-1. This optimized core-shell nanoarchitecture endows the composite electrode with short ion diffusion pathway, rapid ion/electron transfer and high utilization of active materials, which thus result in excellent electrochemical performance of the ternary composite.

Highly surface electron-deficient Co_(9)S_(8) nanoarrays for enhanced oxygen evolution

Tailoring valence electron delocalization of transition metal center is of importance to achieve highly-active electrocatalysts for oxygen evolution reaction(OER).Herein,we demonstrate a“poor sulfur”route to synthesize surface electron-deficient Co_(9)S_(8) nanoarrays,where the binding energy(BE)of Co metal center is considerably higher than all reported Co_(9)S_(8)-based electrocatalysts.The resulting Co_(9)S_(8) electrocatalysts only require the overpotentials(h)of 265 and 326 mV at 10 and 100 mA cm^(-2) with a low Tafel slope of 56 mV dec^-(1) and a 60 hlasting stability in alkaline media.The OER kinetics are greatly expedited with a low reaction activation energy of 27.9 kJ mol^-(1) as well as abundant OOH*key intermediates(24%),thus exhibiting excellent catalytic performances.The surface electron-deficient engineering gives an available strategy to improve the catalytic activity of other advanced non-noble electrocatalysts.

Numerical modeling of condensate droplet on superhydrophobic nanoarrays using the lattice Boltzmann method

In the present study,the process of droplet condensation on superhydrophobic nanoarrays is simulated using a multicomponent multi-phase lattice Boltzmann model.The results indicate that three typical nucleation modes of condensate droplets are produced by changing the geometrical parameters of nanoarrays.Droplets nucleated at the top（top-nucleation mode）,or in the upside interpillar space of nanoarrays（side-nucleation mode）,generate the non-wetting Cassie state,whereas the ones nucleated at the bottom corners between the nanoarrays（bottom-nucleation mode） present the wetting Wenzel state.Time evolutions of droplet pressures at the upside and downside of the liquid phase are analyzed to understand the wetting behaviors of the droplets condensed from different nucleation modes.The phenomena of droplet condensation on nanoarrays patterned with different hydrophilic and hydrophobic regions are simulated,indicating that the nucleation mode of condensate droplets can also be manipulated by modifying the local intrinsic wettability of nanoarray surface.The simulation results are compared well with the experimental observations reported in the literature.

A 3D conducting scaffold with in-situ grown lithiophilic Ni_(2)P nanoarrays for high stability lithium metal anodes

Lithium(Li)metal is the most potential anode material for the next-generation high-energy rechargeable batteries.However,intrinsic surface unevenness and‘hostless’nature of Li metal induces infinite volume effect and uncontrollable dendrite growth.Herein,we design the in-situ grown lithiophilic Ni_(2)P nanoarrays inside nickel foam(PNF).Uniform Ni_(2)P nanoarrays coating presents a very low nucleation overpotential,which induces the homogeneous Li deposition in the entire spaces of three-dimensional(3D)metal framework.Specifically,the lithiophilic Ni_(2)P nanoarrays possess characteristics of electrical conductivity and structural stability,which have almost no expansion and damage during repeating Li plating/stripping.Therefore,they chronically inhibit the growth of Li dendrites.This results in an outstanding Coulombic efficiency(CE)of 98% at 3 mA cm^(-2) and an ultra long cycling life over 2000 cycles with a low overpotential.Consequently,the PNF-Li||LiFePO_(4) battery maintains a capacity retention of 95.3% with a stable CE of 99.9% over 500 cycles at 2 C.

Hybrid architecture design enhances the areal capacity and cycling life of low-overpotential nanoarray oxygen electrode for lithium–oxygen batteries

Transition metal oxide(TMO)nanoarrays are promising architecture designs for self-supporting oxygen electrodes to achieve high catalytic activities in lithium-oxygen(Li-O2)batteries.However,the poor conductive nature of TMOs and the confined growth of nanostructures on the limited surfaces of electrode substrates result in the low areal capacities of TMO nanoarray electrodes,which seriously deteriorates the intrinsically high energy densities of Li-O2 batteries.Herein,we propose a hybrid nanoarray architecture design that integrates the high electronic conductivity of carbon nanoflakes(CNFs)and the high catalytic activity of Co3 O4 nanosheets on carbon cloth(CC).Due to the synergistic effect of two differently featured components,the hybrid nanoarrays(Co3 O4-CNF@CC)achieve a high reversible capacity of3.14 mA h cm-2 that cannot be achieved by only single components.Further,CNFs grown on CC induce the three-dimensionally distributed growth of ultrafine Co3 O4 nanosheets to enable the efficient utilization of catalysts.Thus,with the high catalytic efficiency,hybrid Co3 O4-CNF@CC also achieves a more prolonged cycling life than pristine TMO nanoarrays.The present work provides a new strategy for improving the performance of nanoarray oxygen electrodes via the hybrid architecture design that integrates the intrinsic properties of each component and induces the three-dimensional distribution of catalysts.

Facile fabrication of hierarchical porous Co_3O_4 nanoarrays as a free-standing cathode for lithium–oxygen batteries

Two shapes of Co_3O_4 nanoarrays(i.e., nanosheets, nanowires) with different densities of exposed catalytic active sites were synthesized through a facile hydrothermal method on Ni foam substrates and tested as the binder/carbon free and free-standing cathodes for Li–O_2 batteries. Particularly, the single crystalline feature of Co_3O_4 nanosheets with a predominant high reactivity {112} exposed crystal plane and hierarchical porous nanostructure displayed better catalytic performance for both oxygen reduction reaction(during discharge process) and oxygen evolution reaction(during charge process). Li–O_2 battery with Co_3O_4 nanosheets cathode exhibited a higher discharge specific capacity(965 m Ah g^(-1)), lower discharge/charge over-potential and better cycling performance over 63 cycles at 100 mA g^(-1) with the specific capacity limited at 300 mAh g^(-1). The superior catalytic performance of Co_3O_4 nanosheets cathode is ascribed to the enlarging specific area and increasing the exposed Co^(3+) catalytic active sites within predominant {112} crystal plane which plays the key role in determining the adsorption energy for the reactants, enabling high round-trip efficiency and cyclic life.

In situ confined vertical growth of Co_(2.5)Ni_(0.5)Si_(2)O_(5)(OH)_(4)nanoarrays on rGO for an efficient oxygen evolution reaction

Rational design of oxygen evolution reaction(OER)catalysts at low cost would greatly benefit the economy.Taking advantage of earth-abundant elements Si,Co and Ni,we produce a unique-structure where cobalt-nickel silicate hydroxide[Co_(2.5)Ni_(0.5)Si_(2)O_(5)(OH)_(4)]is vertically grown on a reduced graphene oxide(rGO)support(CNS@rGO).This is developed as a low-cost and prospective OER catalyst.Compared to cobalt or nickel silicate hydroxide@rGO(CS@rGO and NS@rGO,respectively)nanoarrays,the bimetal CNS@rGO nanoarray exhibits impressive OER performance with an overpotential of 307 mV@10 mA cm^(-2).This value is higher than that of CS@rGO and NS@rGO.The CNS@rGO nanoarray has an overpotential of 446 mV@100 mA cm^(-2),about 1.4 times that of the commercial RuO_(2)electrocatalyst.The achieved OER activity is superior to the state-of-the-art metal oxides/hydroxides and their derivatives.The vertically grown nanostructure and optimized metal-support electronic interactions play an indispensable role for OER performance improvement,including a fast electron transfer pathway,short proton/electron diffusion distance,more active metal centers,as well as optimized dualatomic electron density.Taking advantage of interlay chemical regulation and the in-situ growth method,the advanced-structural CNS@rGO nanoarrays provide a new horizon to the rational and flexible design of efficient and promising OER electrocatalysts.

Facet Regulation of Fe_(2)O_(3) via Nanoarray Architecture to Enable High Faradic Efficiency for Electrocatalytic Nitrogen Fixation

We propose a facile facet regulation enabled by nanoarray architecture to achieve a high faradic efficiency of Fe_(2)O_(3) catalyst for NRR. The a-Fe_(2)O_(3) nanorod arrays (NAs) were directly grown on carbon cloth (CC) with specific (104) facet exposure. The highly exposed (104) facets provide abundant unsaturated Fe atoms with dangling bonds as nitrogen reduction reaction catalytically active sites. In addition, the NAs architecture enables the enhanced electrochemical surface area (ECSA) to fully manifest the active sites and maintain the mass diffusion. Thus, the selectively exposed (104) facets coupled with the high ECSA of NAs architecture achieve a high FE of 14.89% and a high yield rate of 17.28 μg h^(-1) cm^(-2). This work presents an effective strategy to develop highly efficient catalytic electrodes for electrochemical NRR via facet regulation and nanoarray architecture.

Quantum plasmons in the hybrid nanostructures of double vacancy defected graphene and metallic nanoarrays

We study the plasmonic properties of hybrid nanostructures consisting of double vacancy defected graphene(DVDGr)and metallic nanoarrays using the time-dependent density functional theory. It is found that DVDGr with pure and mixed noble/transition-metal nanoarrays can produce a stronger light absorption due to the coherent resonance of plasmons than graphene nanostructures. Comparing with the mixed Au/Pd nanoarrays, pure Au nanoarrays have stronger plasmonic enhancement. Furthermore, harmonics from the hybrid nanostructures exposed to the combination of lasers ranged from ultraviolet to infrared and a controlling pulse are investigated theoretically. The harmonic plateau can be broadened significantly and the energy of harmonic spectra is dramatically extended by the controlling pulse. Thus, it is possible to tune the width and intensity of harmonic spectrum to achieve broadband absorption of radiation. The methodology described here not only improves the understanding of the surface plasmon effect used in a DVDGr-metal optoelectronic device but also may be applicable to different optical technologies.

Trifunctional Cu-Mesh/Cu_(2)O@FeO Nanoarrays for Highly Efficient Degradation of Antibiotic, Inactivation of Antibiotic-Resistant Bacteria, and Damage of Antibiotics Resistance Genes

Trifunctional Cu-mesh/Cu_(2)O@FeO nanoarrays heterostructure is designed and fabricated by integrating CuCu_(2)O@FeO nanoarrays onto Cu-mesh(CM)via an in situ growth and phase transformation process.It is successfully applied to efficiently mitigate the antibiotic pollution,including degradation of antibiotics,inactivation of antibiotic-resistant bacteria(ARB),and damage of antibiotics resistance genes(ARGs).Under visible-light irradiation,CM/CuCu_(2)O@FeO nanoarrays exhibit a superior degradation efficiency on antibiotics(e.g.,up to 99%in 25 min for tetracycline hydrochloride,TC),due to the generated reactive oxygen species(ROS),especially the dominant·O^(2−).It can fully inactivate E.coli(HB101)with initial number of~108 CFU mL^(−1) in 10 min,which is mainly attributed to the synergistic effects of 1D nanostructure,dissolved metal ions,and generated ROS.Meanwhile,it is able to damage ARGs after 180 min of photodegradation,including tetA(vs TC)of 3.3 log 10,aphA(vs kanamycin sulfate,KAN)of 3.4 log 10,and tnpA(vs ampicillin,AMP)of 4.4 log 10,respectively.This work explores a green way for treating antibiotic pollution under visible light.

Electronic modulation of sprout-shaped NiCoP nanoarrays by N and Ce doping for efficient overall water splitting

Bifunctional catalysts for hydrogen/oxygen evolution reactions(HER/OER)are urgently needed given the bright future of water splitting hydrogen production technology.Here,the self-supporting N and Ce dual-doped NiCoP nanoarrays(denoted N,Ce-NiCoP/NF)grown on Ni foam are successfully constructed.When the N,Ce-NiCoP/NF simultaneously acts as the HER and OER electrodes,the voltages of 1.54 and 2.14 V are obtained for driving 10 and 500 mA·cm^(-2)with a robust durability,and demonstrate its significant potential for practical water electrolysis.According to both experiments and calculations,the electronic structure of NiCoP may be significantly altered by strategically incorporating N and Ce into the lattice,which in turn optimizes the Gibbs free energy of HER/OER intermediates and speeds up the water splitting kinetics.Moreover,the sprout-shaped morphology significantly increases the exposure of active sites and facilitates charge/mass transfer,thereby augmenting catalyst performance.This study offers a potentially effective approach involving the regulation of anion and cation double doping,as well as architectural engineering,for the purpose of designing and optimizing innovative electrocatalysts.

Current progress in developing metal oxide nanoarrays-based photoanodes for photoelectrochemical water splitting

Solar energy driven photoelectrochemical(PEC) water splitting is a clean and powerful approach for renewable hydrogen production. The design and construction of metal oxide based nanoarray photoanodes is one of the promising strategies to make the continuous breakthroughs in solar to hydrogen conversion efficiency of PEC cells owing to their owned several advantages including enhanced reactive surface at the electrode/electrolyte interface, improved light absorption capability, increased charge separation efficiency and direct electron transport pathways. In this Review, we first introduce the structure,work principle and their relevant efficiency calculations of a PEC cell. We then give a summary of the state-of the-art research in the preparation strategies and growth mechanism for the metal oxide based nanoarrays, and some details about the performances of metal oxide based nanoarray photoanodes for PEC water splitting. Finally, we discuss key aspects which should be addressed in continued work on realizing high-efficiency metal oxide based nanoarray photoanodes for PEC solar water splitting systems.

Ambient ammonia production via electrocatalytic nitrite reduction catalyzed by a CoP nanoarray

Industrial-scale ammonia(NH_(3))production mainly relies on the energy-intensive and environmentally unfriendly Haber-Bosch process.Such issue can be avoided by electrocatalytic N_(2) reduction which however suffers from limited current efficiency and NH3 yield.Herein,we demonstrate ambient NH_(3) production via electrochemical nitrite(NO_(2)^(-))reduction catalyzed by a CoP nanoarray on titanium mesh(CoP NA/TM).When tested in 0.1 M PBS(pH=7)containing 500 ppm N0_(2)^(-),such CoP NA/TM is capable of affording a large NH_(3) yield of 2,260.7±51.5μg·h^(-1)·cm^(-2) and a high Faradaic efficiency of 90.0±2.3%at-0.2 V vs.a reversible hydrogen electrode.Density functional theory calculations reveal that the potential-determining step for NO_(2)^(-)reduction over CoP(112)is*NO2→*NO_(2)H.

Puffing quaternary FexCoyNi1-x-yP nanoarray via kinetically controlled alkaline etching for robust overall water splitting

Designing and constructing bifunctional electrocatalysts with high efficiency,high stability and low cost for overall water splitting to produce clean hydrogen fuel is attractive but highly challenging.Here we constructed puffed quaternary FexCoyNi1-x-yP nanoarrays as bifunctional electrodes for robust overall water splitting.The iron was used as the modulator to manipulate the electron density of NiCoP nanoarray,which could increase the positive charges of metal(Ni and Co)and P sites.The resultant electronic structure of FexCoyNi1-x-yP was supposed to balance the adsorption and desorption of H and accelerate the oxygen evolution reaction(OER)kinetics.Moreover,the morphological structure of FexCoyNi1-x-yP was modulated through the kinetically controlled alkaline etching by using the amphoteric features of initial FeCoNi hydroxide nanowires.The resultant puffed structure has rich porosity,cavity and defects,which benefit the exposure of more active sites and the transport of mass/charge.As a result,the cell integrated with the puffed quaternary FexCoyNi1-x-yP nanoarrays as both the cathode and anode only requires the overpotentials of 25 and 230 mV for hydrogen evolution reaction(HER)and OER at the current density of 10 mA cm^-2 in alkaline media and a cell voltage of 1.48 V to drive the overall water splitting.Moreover,the puffed FexCoyNi1-x-yP demonstrates remarkable durability for continuous electrolysis even at a large current density of 240 mA cm^-2.

Hydrothermal growth of hydroxyapatite and ZnO bilayered nanoarrays on magnesium alloy surface with antibacterial activities

Magnesium alloy(MgA)has been extensively used as orthopedic and cardiovascular scaffolds in virtue of its good biocompatibility,unique biodegradability and excellent mechanical properties.However,poor corrosion resistance and easy infection after implantation seriously limit the potential applications of MgA in the biomedical field.Herein,we fabricated bilayered nanoarrays of hydroxyapatite nanorods(HANRs)and ZnO nanorods(ZnONRs)onto the surface of MgA(MgA-MgO-HANRs-ZnONRs)via micro-arc oxidation(MAO)treatment,microwave-assisted hydrothermal and hydrothermal methods.The morphology and chemical composition of MgA-MgO-HANRs-ZnONRs was characterized by FE-SEM,XRD and EDS,indicating that HANRs-ZnONRs bilayered nanoarrays were fabricated on the surface of MgA-MgO.The surface of MgA-MgO-HANRs-ZnONRs exhibited excellent hydrophilicity as evidenced by the low water contact angle of 3°.Compared with the original MgA,the corrosion resistance of MgA-MgO-HANRs-ZnONRs was obviously improved with decreasing the corrosive current density(icorr)of 2 orders of magnitude.The MgA-MgO-HANRs-ZnONRs performed excellent antibacterial properties with the bactericidal rate of 96.5%against S.aureus and 94.3%against E.coli.

Highly efficient and stable solar-powered desalination by tungsten carbide nanoarray film with sandwich wettability

Solar-powered desalination is a promising way to resolve the worldwide water crisis for its low con- sumption and simple facility. Considering the fragility and aggregations of traditional materials, which may decrease efficiency, we herein introduce a robust tungsten carbide (WC) nanoarray film as a stable and efficient photothermal material, whose absorption is over 97.5% throughout almost the whole solar spectrum range (220–2200 nm) due to nanoarray structure and thus enhanced localized surface plasmon resonance. Besides, for the first time, we modified the film with sandwich wettability. It accelerates evap- oration by reducing water’s reflection of light, enlarging hydrophobic-hydrophilic boundaries, and depressing heat dissipation. Combining high absorption with unique wettability, the WC nanoarray film offers high solar-to-vapor efficiency of 90.8% and produces drinking water at the rate of (1.06 ± 0.10) kg m^(-2)h^(-1)from man-made seawater and (0.98 ± 0.18) kg m^(-2)h^(-1)from heavy metal sewage under one sun (AM 1.5) while 98% performance remains after 1 h×100 times’ reutilization.

Layered double hydroxide-based core-shell nanoarrays for efficient electrochemical water splitting

Electrochemical water splitting is an efficient and clean strategy to produce sustainable energy produc- tions （especially hydrogen） from earth-abundant water. Recently, layered double hydroxide （LDH）-based materi- als have gained increasing attentions as promising electrocatalysts for water splitting. Designing LDHs into hierarchical architectures （e.g., core-shell nanoarrays） is one of the most promising strategies to improve their electrocatalytic performances, owing to the abundant exposure of active sites. This review mainly focuses on recent progress on the synthesis of hierarchical LDH-based core-shell nanoarrays as high performance electrocatalysts for electrochemical water splitting. By classifying different nanostructured materials combined with LDHs, a number of LDH-based core-shell nanoarrays have been developed and their synthesis strategies, structural characters and electrochemical performances are rationally described. Moreover, further developments and challenges in devel- oping promising electrocatalysts based on hierarchical nanostructured LDHs are covered from the viewpoint of fundamental research and practical applications.

Recent advances in TiO_2 nanoarrays/graphene for water treatment and energy conversion/storage

Although TiO2-based nanostructures with unique chemical and physical properties exhibit great promise in water treatment and energy conversion/storage,there still exist some limitations.In order to further improve the photochemical properties,one-dimension TiO2 nanoarrays on the substrate are primarily combined with graphene by various preparation technologies.The composite coating has exhibited extraordinary photocatalytic abilities in the degradation of organic pollutants into less toxic compounds,antimicrobial activity and adsorption capacity in water treatment.Especially,it is easy to recycle after photocatalytic reaction.Additionally,TiO2 nanoarrays/graphene on the substrate(especially flexible substrate)could provide potential opportunities for flexible-device fabrication with excellent photovoltaic conversion efficiency and electrochemical performance in energy conversion/storage devices.As far as we know,the relevant reviews have rarely been reported.Here,we present a comprehensive review on the preparation of TiO2 nanoarrays or TiO2 nanoarrays/graphene,and their application and mechanism in water treatment and energy conversion/storage.