Recent development of LiNi_xCo_yMn_zO_2:Impact of micro/nano structures for imparting improvements in lithium batteries

The recent advancement in the design,synthesis,and fabrication of micro/nano structured LiNixCoyMnzO2 with one-,two-,and three-dimensional morphologies was reviewed.The major goal is to highlight LiNixCoyMnzO2 materials,which have been utilized in lithium ion batteries with enhanced energy and power density,high energy efficiency,superior rate capability and excellent cycling stability resulting from the doping,surface coating,nanocomposites and nano-architecturing.

Synthesis of porous nano/micro structured LiFePO_4/C cathode materials for lithium-ion batteries by spray-drying method

In order to enhance electrochemical properties of LiFePO4 （LFP） cathode materials, spherical porous nano/micro structured LFP/C cathode materials were synthesized by spray drying, followed by calcination. The results show that the spherical precursors with the sizes of 0.5-5 μm can be completely converted to LFP/C when the calcination temperature is higher than 500 ℃. The LFP/C microspheres obtained at calcination temperature of 700 ℃ are composed of numerous particles with sizes of -20 nm, and have well-developed interconnected pore structure and large specific surface area of 28.77 mE/g. The specific discharge capacities of the LFP/C obtained at 700 ℃ are 162.43, 154.35 and 144.03 mA.h/g at 0.5C, 1C and 2C, respectively. Meanwhile, the capacity retentions can reach up to 100% after 50 cycles. The improved electrochemical properties of the materials are ascribed to a small Li＋ diffusion resistance and special structure of LFP/C microspheres.

Preparation of micro/nano-structured ceramic coatings on Ti6Al4V alloy by plasma electrolytic oxidation process

In order to improve the osseointegration and antibacterial activity of titanium alloys,micro/nano-structured ceramic coatings doped with antibacterial element F were prepared by plasma electrolytic oxidation(PEO)process on Ti6Al4V alloy in NaF electrolyte.The influence of NaF concentration(0.15-0.50 mol/L)on the PEO process,microstructure,phase composition,corrosion resistance and thickness of the coatings was investigated using scanning/transmission electron microscopy,energy dispersive spectroscopy,atomic force microscopy,X-ray diffractometer,and potentiodynamic polarization.The results demonstrated that Ti6Al4V alloy had low PEO voltage(less than 200 V)in NaF electrolyte,which decreased further as the NaF concentration increased.A micro/nano-structured coating with 10-15μm pits and 200-800 nm pores was formed in NaF electrolyte;the morphology was different from the typical pancake structure obtained with other electrolytes.The coating formed in NaF electrolyte had low surface roughness and was thin(<4μm).The NaF concentration had a small effect on the phase transition from metastable anatase phase to stable rutile phase,but greatly affected the corrosion resistance.In general,as the NaF concentration increased,the surface roughness,phase(anatase and rutile)contents,corrosion resistance,and thickness of the coating first increased and then decreased,reaching the maximum values at 0.25 mol/L NaF.

Dropwise condensation heat transfer enhancement on surfaces micro/nano structured by a two-step electrodeposition process

Condensation is an important regime of heat transfer which has wide applications in different industries such as power plants,heating,ventilating and air conditioning,and refrigeration.Condensation occurs in two different modes including filmwise (FWC) and dropwise (DWC) condensation.DWC occurring on hydrophobic and superhydrophobic surfaces has a much higher heat transfer capacity than FWC.Therefore,wide investigations have been done to produce DWC in recent years.Superhydrophobic surfaces have micro/nano structures with low surface energy.In this study,a two-step electrodeposition process is used to produce micro/nano structures on copper specimens.The surface energy of specimens is reduced by a self-assembled monolayer using ethanol and 1-octadecanethiol solution.The results show that there is an optimum condition for electrodeposition parameters.For example,a surface prepared by 2000 s step time has 5 times greater heat transfer than FWC while a surface with 4000 s step time has nearly the same heat transfer as FWC.The surfaces of the fabricated specimens are examined using XRD and SEM analyses.The SEM analyses of the surfaces show that there are some micro-structures on the surfaces and the surface porosities are reduced by increasing the second step electrodeposition time.

Superhydrophobic surfaces via controlling the morphology of ZnO micro/nano complex structure

ZnO micro/nano complex structure films, including reticulate papillary nodes, petal-like and flake-hole, have been self-assembled by a hydrothermal technique at different temperatures without metal catalysts. The wettability of the above film surfaces was modified with a simple coating of heptadecafluorodecyltrimethoxy-silane in toluene. After modifying, the surface of ZnO film grown at 50℃ was converted from superhydrophilic with a water contact angle lower than 5° to superhydrophobic with a water contact angle of 165° Additionally, the surface of reticulate papillary nodes ZnO film grown at 100 ℃ had excellent superhydrophobicity, with a water contact angle of 173° and a sliding angle lower than 2° Furthermore, the water contact angle on the surface of petal-like and flake-hole ZnO films grown at 150℃ and 200℃ were found to be 140° and 120°, respectively. The wettability for the samples was found to depend strongly on the surface morphology which results from the growth temperature.

Preparation of calcium carbonate with microstructure and nanostructure from carbide slag for CO_(2) sequestration by using recyclable ammonium chloride

Based on the composition characteristics of carbide slag and the application of polyvinyl chloride,a method of preparing calcium carbonate with microstructure and nanostructure by using carbide slag as a raw material and ammonium chloride as a leaching agent was proposed.The factors for the preparation of calcium carbonate and the effects of different conditions on the crystal phase,grain size,and morphology of calcium carbonate were systematically studied.The results showed that the nanosized calcium carbonate was prepared at 60 mL/min,25°C,no additional ammonia,and 60 min.The product of spherical vaterite was in accordance with the relevant standards for the industrial precipitation of calcium carbonate.Moreover,the reuse of carbonation filtrate was realized.The crystal phase,grain size,and morphology of the carbonation product could be controlled by adjusting the reaction conditions.The manuscript provided a new idea for resource utilization of carbide slag and preparing nanocalcium carbonate.

Energy barrier for configurational transformation of graphene nanoribbon on nanotube

A graphene nanoribbon （GNR） has two basic configurations when winding on the outer surface of a carbon nanotube （CNT）： helix and scroll. Here the transformation between the two configurations is studied utilizing molecular dynamics simulations. The energy barrier during the transformation as well as its relationship with the interfacial energy and the radius of CNT are investigated. Our work offers further insights into the formation of desirable helix/scroll of GNR winding on nanotubes or nanowires, and thus can enable novel design of potential graphene-based electronics.

Hydrophobic Ti_xO_y-C_mH_n Nanoparticle Film Prepared by Plasma Enhanced Chemical Vapor Deposition

The hydrophobic films of TixOy-CmHn. deposited from mixture gases of titanium isopropoxide （TTIP） and oxygen by plasma enhanced chemical vapor deposition （PECVD） were investigated. The films were investigated by scanning electron microscope （ SEM ）, transmission electron microscope （ TEM ）, Fourier transform infrared spectrometer （ FTIR）, X-Ray diffraction （ XRD ）, element analysis （ EA ）, ultraviolet visible spectrometer （ UV-Vis）, and water contact angle （WCA）. The results reveal that the surface of the films is formed by mierosized papillaes aggregated by inorganic and organic phases of complex nanoparticles with size from 50 nm to 200 nm when the discharge power is increased from 40 W to 150 W. All fdms demonstrate the strong broad of Ti-O-Ti stretching vibration at 400 -800cm-1, -CH bending vibration at 1 388 cm -1, and broadening -OH stretching vibration at 3 000-3500 cm-1 With the increase of the discharge power, the asdeposited film changes from amorphous to crystallization. The WCA of the film can be as high as 160°, indicating the hydrophobicity. The films show a similar ultraviolet absorption property as the bulk TiO2 film. The composition of the composition of film deposited at 150 W can be formulated as Tio.302-C1.5H3. Therefore, the composition formula of this hydrophobic film could be expressed as TiO2-C5H10O4.7. It is believed that the complex micro/nano structures of TiO2 and C5H10O4.7 residues are responsible for the observed hydrophobicity and the ultraviolet absorption property of the film.

Laser-based bionic manufacturing

Over millions of years of natural evolution,organisms have developed nearly perfect structures and functions.The self-fabrication of organisms serves as a valuable source of inspiration for designing the next-generation of structural materials,and is driving the future paradigm shift of modern materials science and engineering.However,the complex structures and multifunctional integrated optimization of organisms far exceed the capability of artificial design and fabrication technology,and new manufacturing methods are urgently needed to achieve efficient reproduction of biological functions.As one of the most valuable advanced manufacturing technologies of the 21st century,laser processing technology provides an efficient solution to the critical challenges of bionic manufacturing.This review outlines the processing principles,manufacturing strategies,potential applications,challenges,and future development outlook of laser processing in bionic manufacturing domains.Three primary manufacturing strategies for laser-based bionic manufacturing are elucidated:subtractive manufacturing,equivalent manufacturing,and additive manufacturing.The progress and trends in bionic subtractive manufacturing applied to micro/nano structural surfaces,bionic equivalent manufacturing for surface strengthening,and bionic additive manufacturing aiming to achieve bionic spatial structures,are reported.Finally,the key problems faced by laser-based bionic manufacturing,its limitations,and the development trends of its existing technologies are discussed.

Localized in‑situ deposition:a new dimension to control in fabricating surface micro/nano structures via ultrafast laser ablation

Controllable fabrication of surface micro/nano structures is the key to realizing surface functionalization for various applications.As a versatile approach,ultrafast laser ablation has been widely studied for surface micro/nano structuring.Increasing research eforts in this feld have been devoted to gaining more control over the fabrication processes to meet the increasing need for creation of complex structures.In this paper,we focus on the in-situ deposition process following the plasma formation under ultrafast laser ablation.From an overview perspective,we frstly summarize the diferent roles that plasma plumes,from pulsed laser ablation of solids,play in diferent laser processing approaches.Then,the distinctive in-situ deposition process within surface micro/nano structuring is highlighted.Our experimental work demonstrated that the in-situ deposition during ultrafast laser surface structuring can be controlled as a localized micro-additive process to pile up secondary ordered structures,through which a unique kind of hierarchical structure with fort-like bodies sitting on top of micro cone arrays were fabricated as a showcase.The revealed laser-matter interaction mechanism can be inspiring for the development of new ultrafast laser fabrication approaches,adding a new dimension and more fexibility in controlling the fabrication of functional surface micro/nano structures.

Controlled Synthesis of SnO_2 with Hierarchical Micro/Nano Structure

Preparing SnO2 with hierarchical micro/nano structures by hydrothermal, coordination, templating and electrochemical deposition methods and their mechanisms are investigated. The result shows that the echinus-like SnO2 prepared by Method 1 is a typical Ostwald mechanism that develops from internally to externally. The cabbage-like SnO2 by Method 2 is produced with oxalic acid as complexing agent to set-up precursor of SnO2, and then precursors are bocked around the body that is around the body being bocked. The nest-like SnO2 by Method 3 is controlled by citric acid as coordinator for the nucleation as well as the grow rate and setup process. Spongy-like SnO2 by Method 4 is produced using PST as template, PST is be infiltered into SnO2 precursor by gravity and capillary and treated thermally to form a multiporous structure. The petal-like SnO2 by Method 5 is formed with crystal deposition emergence due to oxidation-reduction reactions of two electrodes in an electric field. XRD analyses shows that the five results are all pure phase SnO2. It provides basic data for SnOE industrial application.

Construction of Zn-incorporated Micro/Nano Hierarchical Structure Coatings on Tantalum

Tantalum(Ta)alloys have been widely used as bone repair materials duc to their excellent biocompatibility.In present work,zinc(Zn)incorporated ceramic coatings with micro/nano hierarchical structure were successfully fabricated on Ta by micro-arc oxidation and hydrothermal treatment.The content of Zn ions is about(1.35士0.3)wt%.Cortex-like rough morphology(Ra:1.504μm)with irregular vermiform slots can be clearly observed on the surface of Ta.More importantly,the coatings resembling the structure of natural bone can release Zn,Ca,and P ions in a controlled and sustained manner.The corrosion resistance ofTa is greatly improved after functionalized with ceramic coatings,confirming by potentiodynamic polarization tests.The bonding strength between the coatings and substrates can be up to 18.9 N.Furthermore,the surface of MAOs-HT@Ta is covered by bonelike apatite after immersed in Simulated Body Fluid(SBF)for three weeks,showing excellently bioactivity.These results suggest that the innovative Zn-incorporated micro/nano hierarchical coatings on Ta may be used as promising candidates for orthopedic implants.

Multiple-dimensional micro/nano structural models for hydrophobicity of butterfly wing surfaces and coupling mechanism

The microstructure, wettability and chemical composition of the butterfly wing surfaces were investigated by a scanning electron microscope, a contact angle meter and a Fourier transform infrared spectrometer. The micro/nano structural models for hydrophobicity of the butterfly wing surfaces were established on the basis of the Cassie equation. The hydrophobicity mechanisms were discussed from the perspective of biological coupling. The butterfly wing surfaces are composed of naturally hydrophobic material and possess micro/nano hierarchical structures, including primary structure （micrometric scales）, secondary structure （nano longitudinal ridges and lateral bridges） and tertiary structure （nano stripes）. The wing surfaces exhibit high hydrophobicity （contact angle 138°-157°） and low adhesion （sliding angle 1°-3°）. The micromorphology and self-cleaning performance of the wing surfaces demonstrate remarkable anisotropism. The special complex wettability ascribes to a coupling effect of the material element and the structure element. In microdimension, the smaller the width and the bigger the spacing of the scale, the stronger the hydrophobicity of the wing surfaces. In nano-dimension, the smaller the height and the smaller the width and the bigger the spacing of the longitudinal ridge, the stronger the hydrophobicity of the wing surfaces. This work promotes our understanding of the hydrophobicity mechanism of bio-surfaces and may bring inspiration for biomimetic design and preparation of smart interfacial materials.

Research progress in improving the performance of PEDOT:PSS/Microand Nano-textured Si heterojunction for hybrid solar cells

Silicon-based hybrid solar cells(HSCs),especially PEDOT:PSS/Si HSC,have attracted the interest of researchers because they combine the advantages of organic and inorganic materials.A high quality PEDOT:PSS/Si heterojunction is the key to the good performance of PEDOT:PSS/Si HSC.However,as generally requisite to enhance light absorption for HSCs,Si Micro/Nano structures will reduce the interface contact quality between PEDOT:PSS and Si surface.The inferior interface contact quality will limit the separation efficiency of the photogenerated carriers.In this paper,we summarize the research progress in improving the interface contact between Si Micro/Nano structures and PEDOT:PSS film from three aspects:the optimization of Si Micro/Nano structures aimed to improve the fluid properties of PEDOT:PSS solution,the material modification of PEDOT:PSS and interface modification with the purpose to enlarge the heterojunction area and improve the electrical contact,and the specific deposition process of PEDOT:PSS solution developed to achieve the high filling rate of PEDOT:PSS on Si Micro/Nano structures.The insight of this paper is helpful for the preparation of high-quality heterojunction,which is vitally important for the development of high efficiency PEDOT:PSS/Si HSCs.

Experimental Study of Static Contact-angle on Peak-like Microstructural Surfaces Produced by PIII Technology

Plasma immersion ion implantation(PIII) was used to fabricate micro/nano structures on monocrystalline Si surfaces with different ratios of mixed gases(SF_6/O_2). The micro/nano structures on the surfaces of the sample were characterized by scanning electron microscopy(SEM) and atomic force microscopy(AFM). The results showed that with increasing ratio of mixed gases(SF_6/O_2), the height of the micro/nano structures first increased and then decreased. Contact-angle measurements indicated that the surfaces' micro/nano structures have an obvious effect on the contact-angle, and could cause a change in surface wettability. The theoretical analysis of contact-angle showed that the Wenzel and Cassie theories cannot predict the contact-angle of a roughened surface accurately, and should be corrected for practical applications using an actual model. Moreover, the contact-angle first increased and then decreased with increasing ratio of mixed gases(SF_6/O_2), which is in accordance with the change of the height of micro/nano structures.

Effective strategy to achieve a metal surface with ultralow reflectivity by femtosecond laser fabrication

An effective and simple method is proposed for fabricating the micro/nano hybrid structures on metal surfaces by adjusting femtosecond laser fluence,scanning interval,and polarization.The evolution of surface morphology with the micro/nano structures is discussed in detail.Also,the mechanism of light absorption by the micro/nano hybrid structures is revealed.Compared with the typical periodic light-absorbing structures,this type of micro/nano hybrid structures has an ultralow average reflectivity of 2%in the 250–2300 nm spectral band and the minimum 1.5%reflectivity in UV band.By employing this method,large areas of the micro/nano hybrid structures with high consistency could be achieved.

Progress of passive daytime radiative cooling technologies towards commercial applications

Global warming has become one of the major environmental problems facing mankind in the 21st century,The existing refrigeration technology of buildings,like air conditioning,consumes a lot of energy.Passive daytime radiative cooling technology works without consuming energy.nor emitting carbon dioxide and other greenhouse gases.This review summarizes the development of daytime passive radiative cooling technologyfrom the basic principles,structure and materials of radiative coolers;analyses and evaluates the various existing radiative coolers.The core of radiative cooling lies in the combination of multi-scale micro/nano structures.The cooler reflects sunlight thus preventing the building from being heated up;while allows the building toradiate its own heat out thus being cooled down;meanwhile maintains the temperature difference by the heat insulation effect ofthe porous structure in theflm.The common challenges and potential solutions for the commercialization of radiative cooling technologies are analyzed,which may promote the applications of the technology in the near future.

Multishelled CuO/Cu_(2)O induced fast photo-vapour generation for drinking water

Solar thermal interfacial water evaporation is proposed as a promising route to address freshwater scarcity,which can reduce energy consumption and have unlimited application scenarios.The large semiconductor family with controllable bandgap and good chemo-physical stability are considered as good candidates for photo-evaporation.However,the evaporation rate is not satisfactory because the rational control of nano/micro structure and composition is still in its infancy stage.Herein,by systemically analyzing the photo-thermal evaporation processes,we applied the hollow multishelled structure(HoMS)into this application.Benefiting from the multishelled and hierarchical porous structure,the light absorption,thermal regulation,and water transport are simultaneously optimized,resulting in a water evaporation rate of 3.2 kg·m^(-2)·h^(-1),which is among the best performance in solar-vapour generation.The collected water from different water resources meets the World Health Organization standard for drinkable water.Interestingly,by using the CuO/Cu_(2)O system,reactive oxygen species were generated for water disinfection,showing a new route for efficient solar-vapour generation and a green way to obtain safe drinking water.