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.

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.

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.

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.

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.

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.

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.

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.

Regulation of TiO_(2) nanoarrays on titanium implants for enhanced osteogenic activity and immunomodulation

The surface topography of implants plays a major role in osteogenesis and immunomodulation.In this study,three types of TiO_(2) nanoarrays including nanorod arrays with a diameter of 45 nm(TiO_(2)-N),nanorod arrays with a diameter of 60 nm(TiO_(2)-N N),and nanocone arrays(TiO_(2)-NW)are prepared on titanium and the behavior of bone marrow stromal cells(BMSCs)and polarization of macrophages are studied.Compared to the planar titanium control,TiO_(2) nanoarrays facilitate osteogenesis of BMSCs and stimulate the pro-healing M2 phenotype.However,adhesion,spreading,proliferation,and osteogenic differentiation of BMSCs are more pronounced on TiO_(2)-N N than both TiO_(2)-N and TiO_(2)-NW.TiO_(2)-NN also produces the best immune microenvironment,while TiO_(2)-NW is more favorable than TiO_(2)-NN from the viewpoint of cell adhesion and spreading of osteoblasts.

CC@BCN@PANI core-shell nanoarrays as ultra-high cycle stability cathode for Zn-ion hybrid supercapacitors

Exploring cathode materials that combine excellent cycling stability and high energy density poses a challenge to aqueous Zn-ion hybrid supercapacitors(ZHSCs).Herein,polyaniline(PANI)coated boron-carbon-nitrogen(BCN)nanoarray on carbon cloth surface is prepared as advanced cathode materials via simple high-temperature calcination and electrochemical deposition methods.Because of the excellent specific capacity and conductivity of PANI,the CC@BCN@PANI core-shell nanoarrays cathode shows an excellent ion storage capability.Moreover,the 3D nanoarray structure can provide enough space for the volume expansion and contraction of PANI in the charging/discharging cycles,which effectively avoids the collapse of the microstructure and greatly improves the electrochemical stability of PANI.Therefore,the CC@BCN@PANI-based ZHSCs exhibit superior electrochemical performances showing a specific capacity of 145.8 mAh/g,a high energy density of 116.78 Wh/kg,an excellent power density of 12 kW/kg,and a capacity retention rate of 86.2%after 8000 charge/discharge cycles at a current density of 2 A/g.In addition,the flexible ZHSCs(FZHSCs)also show a capacity retention rate of 87.7%at the current density of 2 A/g after 450 cycles.

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.

Enhancing electrocatalytic N_(2)-to-NH_(3) fixation by suppressing hydrogen evolution with alkylthiols modified Fe_(3)P nanoarrays

Electrocatalytic N_(2) reduction provides an attractive alternative to Haber-Bosch process for artificial NH_(3) synthesis.The difficulty of suppressing competing proton reduction,however,largely impedes its practical use.Herein,we design a hydrophobic octadecanethiol-modified Fe_(3)P nanoarrays supported on carbon paper(C18@Fe_(3)P/CP)to effectively repel water,concentrate N_(2),and enhance N_(2)-to-NH_(3) conversion.Such catalyst achieves an NH_(3) yield of 1.80×10^(-10) mol s^(-1)·cm^(-2) and a high Faradaic efficiency of 11.22%in 0.1 M Na_(2)SO_(4),outperforming the non-modified Fe_(3)P/CP(2.16×10^(-11) mol s^(-1)·cm^(-2),0.9%)counterpart.Significantly,C18@Fe_(3)P/CP renders steady Nrfixing activlty/selectivity in cycling test and exhibits durability for at least 25 h.First-principles calculations suggest that the surface electronic structure and chemical activity of Fe_(3)P can be well tuned by the thiol modification,which facilitates N_(2) electroreduction activity and catalytic formation of NH_(3).

Phosphorous-doped bimetallic sulfides embedded in heteroatom-doped carbon nanoarrays for flexible all-solid-state supercapacitors

Flexible supercapacitors(SCs)have become a popular research topic due to their extra-long service life,foldability,and wearability.Nevertheless,their low energy density restricts their applications.Here,we synthesized phosphorus-doped bimetallic sulfides embedded in heteroatom-doped(N,S,and P)carbon shells(P-ZCS/HC)using a simple approach to create high-performance flexible electrodes.The three-dimensional architecture made by interlaced nanosheets was preserved,and raised nanoparticles appeared on the rough surface during the annealing operation,increasing the specific surface area and potential exposure to the electrolyte.It is noteworthy that the optimal P-ZCS/HC electrode possessed a remarkable capacity of 1080 C g^(-1)at 1 A g^(-1)along with superb cycling stability.These extraordinary properties were primarily caused by plentiful redox reactions,enhanced conductivity,and synergic effects of the P-doped metal sulfides and heteroatom-doped carbon shells.Density functional theory simulations confirmed the good function of the P-doped electrodes and their ability to boost conductivity,improve reactive dynamics,and promote OH-adsorption.Notably,the assembled all-solid-state hybrid SC exhibited a maximum energy density of 62.9 W h kg^(-1)and a power density of 16 k W kg^(-1),while being able to maintain 92.0%of its initial capacity after 10,000 cycles.This systematic report provides new insight into the design and synthesis of electrodes with complex components and outstanding structures for the flexible energy field.

The enhanced performance of piezoelectric nanogenerator via suppressing screening effect with Au particles/ZnO nanoarrays Schottky junction

This paper describes a novel strategy to weaken the piezopotential screening effect by forming Schottky junctions on the ZnO surface through the introduction of Au particles onto the surface. With this approach, the piezoelectric-energyconversion performance was greatly enhanced. The output voltage and current density of the Au@ZnO nanoarray-based piezoelectric nanogenerator reached 2 V and 1 μA/cm^2, respectively, 10 times higher than the output of pristine ZnO nanoarray-based piezoelectric nanogenerators. We attribute this enhancement to dramatic suppression of the screening effect due to the decreased carrier concentration, as determined by scanning Kelvin probe microscope measurements and impedance analysis. The lowered capacitance of the Au@ZnO nanoarraybased piezoelectric nanogenerator also contributes to the improved output. This work provides a novel method to enhance the performance of piezoelectric nanogenerators and possibly extends to piezotronics and piezophototronics.

Helical copper-porphyrinic framework nanoarrays for highly efficient CO_(2) electroreduction

In recent years, metal-organic frameworks(MOFs) have been extensively investigated as electrocatalysts due to their highly efficient electroreduction of CO_(2). Herein,the electrocatalytic CO_(2)reduction reaction was investigated by growing helical Cu-porphyrinic MOF Cu meso-tetra(4-carboxyphenyl)porphyrin(TCPP) on Cu(OH)_(2) nanoarrays(HCu TCPP@Cu(OH)_(2)) using a sacrificial template method. The electrocatalytic results showed that the H-Cu TCPP@Cu(OH)_(2) nanoarrays exhibited a high acetic acid Faradaic efficiency(FE) of 26.1% at-1.6 V vs. Ag/Ag^(+), which is much higher than the value of 19.8% obtained for non-helical Cu TCPP@Cu(OH)_(2)(n H-Cu TCPP@Cu(OH)_(2)). The higher efficiency may be because space was more effectively utilized in the helical MOF nanoarrays, resulting in a greater number of active catalytic sites. Furthermore, in situ diffuse reflectance infrared Fourier transform spectra showed that the H-Cu TCPP@Cu(OH)_(2) nanoarrays have much stronger CO linear adsorption, indicating a better selectivity of acetic acid than that of n H-Cu TCPP@Cu(OH)_(2). In this study, we develop new helical nanomaterials and propose a new route to enhance the reduction of CO_(2).

Ni_(3)S_(2)@NiWO_(4)nanoarrays towards all-solid-state hybrid supercapacitor with record-high energy density

The rational design and synthesis of hybrid-type electrode nanomaterials are significant for their diverse applications,including their potential usage as high-efficiency nanoarchitectures for supercapacitors(SCs)as a class of promising energy-storage systems for powering next-generation electric vehicles and electronic devices.Here,we reported a facile and controllable synthesis of core-shell Ni_(3)S_(2)@NiWO_(4)nanoarrays to fabricate a freestanding electrode for hybrid SCs.Impressively,the as-prepared freestanding Ni_(3)S_(2)@NiWO_(4)electrode presents an ultrahigh areal capacity of 2032μA h cm^(-2)at 5 mA cm^(-2),and a capacity retention of 63.6%even when the current density increased up to 50 mA cm^(-2).Remarkably,the Ni_(3)S_(2)@NiWO_(4)nanoarraybased hybrid SC delivers a maximum energy density of 1.283 mW h cm^(-2)at 3.128 mW cm^(-2)and a maximum power density of 41.105 mW cm^(-2)at 0.753 mW h cm^(-2).Furthermore,the hybrid SC exhibits a capacity retention of 89.6%even after continuous 10,000 cycles,proving its superior stability.This study provides a facile pathway to rationally design a variety of core-shell metal nanostructures for high-performance energy storage devices.

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.

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.