Steering surface reconstruction of hybrid metal oxides for efficient oxygen evolution reaction in water splitting and zinc-air batteries

Surface reconstruction yields real active species in electrochemical oxygen evolution reaction(OER)conditions;however,rationally regulating reconstruction in a targeted manner for constructing highly active OER electrocatalysts remains a formidable challenge.Here,an electrochemical activation strategy with selective etching was utilized to guide the reconstruction process of a hybrid cobalt-molybdenum oxide(CoMoO_(4)/Co_(3)O_(4)@CC)in a favorable direction to improve the OER performance.Both in-situ Raman and multiple ex-situ characterization tools demonstrate that controlled surface reconstruction can be easily achieved through Mo etching,with the formation of a dynamically stable amorphous-crystalline heterostructure.Theoretical calculations together with experimental results reveal that the synergistic effects between amorphous CoOOH and crystalline Co_(3)O_(4) are crucial in enhancing the catalytic performance.Consequently,the reconstructed CoMoO_(4)/Co_(3)O_(4)@CC exhibits a low overpotential of 250 mV to achieve a current density of 10 mA cm^(-2) in 1 M KOH,and more importantly it can be practiced in electrolytic water splitting and rechargeable zinc-air batteries devices,achieving ultra-long stability for over 500 and 1200 h,respectively.This work provides a promising route for the construction of high-performance electrocatalysts.

Covalency competition induced selective bond breakage and surface reconstruction in manganese cobaltite towards enhanced electrochemical charge storage

Manganese cobaltite(MnCo_(2)_(4))is a promising electrode material because of its attractive redox chemistry and excellent charge storage capability.Our previous work demonstrated that the octahedrally-coordinated Mn are prone to react with the hydroxyl ions in alkaline electrolyte upon electrochemical cycling and separates on the surface of spinel to reconstruct into d-MnO_(2) nanosheets irreversibly,thus results in a change of the reaction mechanism with Kþion intercalation.However,the low capacity has greatly limited its practical application.Herein,we found that the tetrahedrally-coordinated Co_(2) þions were leached when MnCo_(2)_(4) was equilibrated in 1 mol L^(-1) HCl solution,leading to the formation of layered CoOOH on MnCo_(2)_(4) surface which is originated from the covalency competition induced selective breakage of the CoT–O bond in CoT–O–CoO and subsequent rearrangement of free Co_(6) octahedra.The as-formed CoOOH is stable upon cycling in alkaline electrolyte,exhibits conversion reaction mechanism with facile proton diffusion and is free of massive structural evolution,thus enables utilization of the bulk electrode material and realizes enhanced specific capacity as well as facilitated charge transfer and ion diffusion.In general,our work not only offers a feasible approach to deliberate modification of MnCo_(2)_(4)'s surface structure,but also provides an in-depth understanding of its charge storage mechanism,which enables rational design of the spinel oxides with promising charge storage properties.

Medical and surgical approach to ocular surface reconstruction

Ocular surface disease(OSD)can have a severe impact on patients as it can lead to visual impairment and persistent discomfort.Ocular surface reconstruction(OSR)is an approach to the management of ocular diseases that cause structural damage to the ocular surface.OSR encompasses both medical and surgical treatment options.In this review,we discuss the medical and surgical strategies used in OSR.Medical management often aims to treat tear insufficiency,inflammation,and keratinization.Surgical treatments may be employed for a variety of reasons,including failure of medical management.This may include improving the oculo-palpebral structures in order to improve lid positioning and tear film.Additional therapies focus on improving tear production,such as through salivary gland transplantation.In situations where the ocular surface is so severely damaged that there is loss of limbal stem cells,limbal stem cell transplant(LSCT)may be indicated.Other surgeries such as amniotic membrane transplant(AMT)and conjunctival flaps(CFs)can help promote corneal healing.Finally,in severe situations where the cornea is beyond salvage,corneal transplantation,such as a penetrating keratoplasty(PKP),can be considered.OSR often requires a combination of medical and surgical approaches targeted to each specific patient’s presentation in order to achieve optimal outcomes.

Etching‑Induced Surface Reconstruction of NiMoO_(4) for Oxygen Evolution Reaction

Rational reconstruction of oxygen evolution reaction(OER)precatalysts and performance index of OER catalysts are crucial but still challenging for universal water electrolysis.Herein,we develop a double-cation etching strategy to tailor the electronic structure of NiMoO_(4),where the prepared NiMoO_(4) nanorods etched by H_(2)O_(2) reconstruct their surface with abundant cation deficiencies and lattice distortion.Calculation results reveal that the double cation deficiencies can make the upshift of d-band center for Ni atoms and the active sites with better oxygen adsorption capacity.As a result,the optimized sample(NMO-30M)possesses an overpotential of 260 mV at 10 mA cm−2 and excellent long-term durability of 162 h.Importantly,in situ Raman test reveals the rapid formation of high-oxidation-state transition metal hydroxide species,which can further help to improve the catalytic activity of NiMoO_(4) in OER.This work highlights the influence of surface remodification and shed some light on activating catalysts.

Surface reconstruction of Se-doped NiS_(2) enables high-efficiency oxygen evolution reaction

Surface reconstruction of electrocatalysts has been widely witnessed during the electrochemical processes.Here,NiS_(2),NiSe_(2), and Se doped NiS_(2)(Se-NiS_(2)) are fabricated for oxygen evolution reaction(OER) through a mild sulfuration and/or selenylation process of Ni(OH)_(2) supported on carbon cloth(CC).Through careful in-situ Raman spectroscopy and ex-situ X-ray photoelectron spectroscopy,surface reconstruction of NiS_(2),NiSe_(2),and Se-NiS_(2) during the OER process has been revealed.A potentialdependent study shows that Se-NiS_(2) undergoes surface evolution at lower potentials and requires the lowest potential for conversion to NiOOH as a highly OER-active species,accompanied by the leaching of SO_(4)^(2-) and SeO_(4)^(2-) that can again be adsorbed on the catalyst surface to enhance the catalytic activity.Density functional theory(DFT) calculations confirm that Se-NiS_(2) is more susceptible to surface oxidation through the OER process.Therefore,Se-NiS_(2) exhibits outstanding OER activity and stability in alkaline conditions,requiring an overpotential of 343 mV at a current density of 50 mA cm^(-2).A novel insight is provided by our work in understanding the surface reconstruction and electrocatalytic mechanism of Ni-based chalcogenides.

Unveiling the parasitic-reaction-driven surface reconstruction in Ni-rich cathode and the electrochemical role of Li_(2)CO_(3)

Nickel-rich transition-metal oxides are widely regarded as promising cathode materials for high-energydensity lithium-ion batteries for emerging electric vehicles. However, achieving high energy density in Ni-rich cathodes is accompanied by substantial safety and cycle-life obstacles. The major issues of Ni-rich cathodes at high working potentials are originated from the unstable cathode-electrolyte interface, while the underlying mechanism of parasitic reactions towards surface reconstructions of cathode materials is not well understood. In this work, we controlled the Li_(2)CO_(3) impurity content on LiNi_(0.83)Mn_(0.1)Co_(0.07)O_(2) cathodes using air, tank-air, and O_(2) synthesis environments. Home-built high-precision leakage current and on-line electrochemical mass spectroscopy experiments verify that Li_(2)CO_(3) impurity is a significant promoter of parasitic reactions on Ni-rich cathodes. The rate of parasitic reactions is strongly correlated to Li_(2)CO_(3) content and severe performance deterioration of Ni83 cathodes.The post-mortem characterizations via high-resolution transition electron microscope and X-ray photoelectron spectroscopy depth profiles reveal that parasitic reactions promote more Ni reduction and O deficiency and even rock-salt phase transformation at the surface of cathode materials. Our observation suggests that surface reconstructions have a strong affiliation to parasitic reactions that create chemically acidic environment to etch away the lattice oxygen and offer the electrical charge to reduce the valence state of transition metal. Thus, this study advances our understanding on surface reconstructions of Nirich cathodes and prepares us for searching for rational strategies.

COMPLEX SURFACE RECONSTRUCTION BASED ON OBJECT-ORIENTED DEVELOPING TOOL VBA

Taking AutoCAD2000 as platform, an algorithm for the reconstruction ofsurface from scattered data points based on VBA is presented. With this core technology customerscan be free from traditional AutoCAD as an electronic board and begin to create actual presentationof real-world objects. VBA is not only a very powerful tool of development, but with very simplesyntax. Associating with those solids, objects and commands of AutoCAD 2000, VBA notably simplifiesprevious complex algorithms, graphical presentations and processing, etc. Meanwhile, it can avoidappearance of complex data structure and data format in reverse design with other modeling software.Applying VBA to reverse engineering can greatly improve modeling efficiency and facilitate surfacereconstruction.

3D surface reconstruction based on binocular vision using structured light

A 3D surface reconstruction method using a binocular stereo vision technology and a coded structured light,which combines a gray code with phase-shift has been studied.The accuracy of the 3 D surface reconstruction mainly depends on the decoding of gray code views and phase-shift views.In order to find the boundary accurately,gray code patterns and their inverses are projected onto a human eye plaster model.The period dislocation between the gray code views and the phase-shift views in the course of decoding has been analyzed and a new method has been proposed to solve it.The splicing method is based on feature points.The result of the 3D surface reconstruction shows the accuracy and reliability of our method.

Surface Reconstruction of 3D Scattered Data with Radial Basis Functions

We use Radial Basis Functions （RBFs） to reconstruct smooth surfaces from 3D scattered data. An object＇s surface is defined implicitly as the zero set of an RBF fitted to the given surface data. We propose improvements on the methods of surface reconstruction with radial basis functions. A sparse approximation set of scattered data is constructed by reducing the number of interpolating points on the surface. We present an adaptive method for finding the off-surface normal points. The order of the equation decreases greatly as the number of the off-surface constraints reduces gradually. Experimental results are provided to illustrate that the proposed method is robust and may draw beautiful graphics.

Common (π,π) Band Folding and Surface Reconstruction in Fe As-Based Superconductors

High resolution angle-resolved photoemission spectroscopy(ARPES)measurements are carried out on CaKFe_4 As_4,KCa_2 Fe_4 As_4 F_2 and(Ba_(0.6)K_(0.4))Fe_2 As_2 superconductors.Clear evidence of band folding between the Brillouin zone center and corners with a(π,π)wave vector has been found from the measured Fermi surface and band structures in all the three kinds of superconductors.A dominant √2×√2 surface reconstruction is observed on the cleaved surface of CaKFe_4As_4 by scanning tunneling microscopy(STM)measurements.We propose that the commonly observed √2×√2 reconstruction in the FeAs-based superconductors provides a general scenario to understand the origin of the(π,π)band folding.Our observations provide new insights in understanding the electronic structure and superconductivity mechanism in iron-based superconductors.

PHYSICS-BASED ILLUMINATION MODEL FOR METAL SURFACE RECONSTRUCTION IN RE

Representation of roughness is introduced and the rationality of applying thephysics-based model in RE is analyzed at first. Then the scattering theory of electromagnetic waveis simplified and deduced to a physics-based model according to the characteristics of the surfaceto be reconstructed in RE. At last, the intensity diagrams of reflected field distribution areprovided to prove the feasibility of the presented model and some spheres are rendered with thismodel.

Surface reconstruction on stishovite SiO_2,HfO_2 and rutile TiO_2 (001)

This paper systematically investigates the surface reconstruction processes and patterns on stishovite SiO2, HfO2 and rutile TiO2 （001） by using classical molecular dynamics. It is found that these three surfaces relax instead of reconstruction at 0 K, and have little possibility to reconstruct below 40 K. Above 40 K, surface reconstructions take place as collective atomic motion which can be speeded by higher temperature or compressed strain. Several reconstruction patterns with approximate surface energies are found, and electrostatic potentials on them are also provided in comparison with possible microscopic results.

Scanning tunneling microscopy study of surface reconstruction induced by N adsorption on Cu(100) surface

The reconstructed structure of Cu （100） surface induced by atomic N adsorption is studied by using scanning tunneling microscopy （STM）. The 2D structure of copper boundary between neighbouring N covered islands is found to be sensitive to the growth conditions, e.g. N＋ bombardment time and annealing temperature. The copper boundary experiences a transition from nano-scale stripe to nano-particle when the substrate is continuously annealed at 623~K for a longer time. A well-defined copper-stripe network can be achieved by precisely controlling the growth conditions, which highlights the possibility of producing new templates for nanofabrication.

Surface reconstruction and structural transformation of twodimensional Ni-Fe MOFs for oxygen evolution in seawater media

As a four-electron transfer reaction,oxygen evolution reaction(OER)is limited by large overpotential and slow kinetics.Here,we in-situ synthesized two-dimensional(2D)Ni-Fe metal-organic framework nanosheets on nickel foam(NixFe-TPA/NF,TPA=terephthalic acid)for oxygen evolution in alkaline and alkaline seawater electrolytes.In 1 M KOH,Ni3Fe-TPA/NF shows a low overpotential(η10)of 189 mV at 10 mA·cm^(-2) and an ultra-low overpotential of only 260 mV at 500 mA·cm^(-2).In alkaline seawater,Ni3Fe-TPA/NF still provides impressive OER performance,with anη10 of 265 mV.In-situ Raman characterization results show that the phase transition occurs during the OER,and Ni3FeOOH with more oxygen vacancies is in-situ formed,reducing the OER energy barrier.Density functional theory(DFT)reveals that the synergy between Ni and Fe reduces the energy barrier and accelerates the rate-determining step.In addition,the ultra-thin 2D sheet structure and the close combination of Ni3FeOOH and highly conductive NF support ensure the high catalytic OER activity.Therefore,the surface reconstruction and structural modification strategy can be used to design and prepare high-performance OER electrocatalysts for energy-related applications.

Controllable surface reconstruction of copper foam for electrooxidation of benzyl alcohol integrated with pure hydrogen production

Electrocatalytic water splitting that is coupled with electrocatalytic chemical oxidation is considered as one of the promising methods for efficiently obtaining hydrogen energy and fine chemicals.Herein,we focus on an electrochemical redox activation strategy to rationally manipulate the microstructure and surface valence states of copper foam(CF)and boost the corresponding performance towards electrocatalytic benzyl alcohol oxidation(EBA),accompanied by the efficient hydrogen production.Correspondingly,the Cu(II)‐dominated species are gradually formed on the CF surface with the dissolution and redeposition of copper in the suitable potential range.The new species containing Cu2O,CuO,and Cu(OH)2 during surface reconstruction process of the CF were confirmed by multiple characterization techniques.After 220‐cycled activation(CF‐220),the activated CF achieves an increase of current density for EBA in anode from 9.5 for the original CF to 29.3 mmol/cm2,while the pure hydrogen yield increases threefold than that of the original CF at 1.5 VRHE.The produced new species can endow the CF‐220 with abundant acidity sites,which can enhance the adsorption toward Lewis‐basicity benzyl alcohol,confirmed by NH3‐temperature‐programmed desorption.In situ Raman result further reveals that the as‐produced CuO,Cu(OH)2,and Cu(OH)42−are the main active species toward the EBA process.

Cu_(2−x)S derived copper nanoparticles:A platform for unraveling the role of surface reconstruction in efficient electrocatalytic CO_(2)-to-C_(2)H_(4)conversion

Cu-based electrocatalysts have provoked much attention for their high activity and selectivity in carbon dioxide(CO_(2))conversion into multi-carbon hydrocarbons.However,during the electrochemical reaction,Cu catalysts inevitably undergo surface reconstruction whose impact on CO_(2)conversion performance remains contentious.Here we report that polycrystalline Cu nanoparticles(denoted as Cu-s)with rich high-index facets,derived from Cu_(2−x)S through desulphurization and surface reconstruction,offer an excellent platform for investigating the role of surface reconstruction in electrocatalytic CO_(2)conversion.During the formation of Cu-s catalyst,the two stages of desulphurization and surface reconstruction can be clearly resolved by in situ X-ray absorption spectroscopy and OH−adsorption characterizations,which are well correlated with the changes in electrocatalytic performance.It turns out that the high CO_(2)conversion performance,achieved by the Cu-s catalyst(Faradic efficiency of 68.6%and partial current density of 40.8 mA/cm^(2)in H-cell toward C_(2)H_(4)production),is attributed to the increased percentage of high-index facets in Cu-s during the surface reconstruction.Furthermore,the operando electrochemical Raman spectroscopy further reveals that the conversion of the CO_(2)into the C_(2)H_(4)on Cu-s is intermediated by the production of*COCHO.Our findings manifest that the surface reconstruction is an effective method for tuning the reaction intermediate of the CO_(2)conversion toward high-value multicarbon(C2+)chemicals,and highlight the significance of in situ characterizations in enhancing the understanding of the surface structure and its role in electrocatalysis.

Surface reconstruction,doping and vacancy engineering to improve the overall water splitting of CoP nanoarrays

Development of a general regulatory strategy for efficient overall water splitting remains a challenging task.Herein,a simple,costfairness,and general fluorination strategy is developed to realize surface reconstruction,heteroatom doping,and vacancies engineering over cobalt phosphide(CoP)for acquiring high-performance bifunctional electrocatalysts.Specifically,the surface of CoP nanoarrays(NAs)becomes rougher,meanwhile F doped into CoP lattice and creating amounts of P vacancies by fluorination,which caused the increase of active sites and regulation of charge distribution,resulting the excellent electrocatalyst performance of F-CoP NAs/copper foam(CF).The optimized F-CoP NAs/CF delivers a lower overpotential of only 35 mV at 10 mA·cm^(−2)for hydrogen evolution reaction(HER)and 231 mV at 50 mA·cm^(−2)for oxygen evolution reaction(OER),and the corresponding overall water splitting requires only 1.48 V cell voltage at 10 mA·cm^(−2),which are superior to the most state-of-theart reported electrocatalysts.This work provides an innovative and feasible strategy to construct efficient electrocatalysts.

Lifting surface reconstruction of Au(100)by tellurium adsorption

The Au(100)surface has been a subject of intense studies due to excellent catalytic activities and its model character for surface science.However,the spontaneous surface reconstruction buries active Au(100)plane and limits practical applications,how to controllably eliminate the surface reconstruction over large scale remains challenging.Here,we experimentally and theoretically demonstrate that simple decoration of the Au(100)surface by tellurium(Te)atoms can uniquely lift its reconstruction over large scale.Scanning tunneling microscopy imaging reveals that the lifting of surface reconstruction preferentially starts from the boundaries of distinct domains and then extends progressively into the domains with the reconstruction rows perpendicular to the boundaries,leaving a Au(100)-(1×1)surface behind.The Au(100)-(1×1)is saturated at~84%±2%with respect to the whole surface at a Te coverage of 0.16 monolayer.With further increasing the Te coverage to 0.25 monolayer,the Au(100)-(1×1)surface becomes reduced and overlapped by a well-ordered(2×2)-Te superstructure.No similar behavior is found for Te-decorated Au(111),Cu(111),Cu(100)surfaces,nor for the decorated Au(100)with other elements.This result may pave the way to design Au-based catalysts and,as an intermediate step,even potentially open a new route to constructing complex transition metal dichalcogenides.

Reconstruction and stability of Fe_(3)O_(4)(001)surface:An investigation based on particle swarm optimization and machine learning

Magnetite nanoparticles show promising applications in drug delivery,catalysis,and spintronics.The surface of magnetite plays an important role in these applications.Therefore,it is critical to understand the surface structure of Fe_(3)O_(4)at atomic scale.Here,using a combination of first-principles calculations,particle swarm optimization(PSO)method and machine learning,we investigate the possible reconstruction and stability of Fe_(3)O_(4)(001)surface.The results show that besides the subsurface cation vacancy(SCV)reconstruction,an A layer with Fe vacancy(A-layer-V_(Fe))reconstruction of the(001)surface also shows very low surface energy especially at oxygen poor condition.Molecular dynamics simulation based on the iron–oxygen interaction potential function fitted by machine learning further confirms the thermodynamic stability of the A-layer-V_(Fe)reconstruction.Our results are also instructive for the study of surface reconstruction of other metal oxides.

Sea surface reconstruction from marine radar images using deep convolutional neural networks

The sea surface reconstructed from radar images provides valuable information for marine operations and maritime transport.The standard reconstruction method relies on the three-dimensional fast Fourier transform(3D-FFT),which introduces empirical parameters and modulation transfer function(MTF)to correct the modulation effects that may cause errors.In light of the convolutional neural networks’(CNN)success in computer vision tasks,this paper proposes a novel sea surface reconstruction method from marine radar images based on an end-to-end CNN model with the U-Net architecture.Synthetic radar images and sea surface elevation maps were used for training and testing.Compared to the standard reconstruction method,the CNN-based model achieved higher accuracy on the same data set,with an improved correlation coefficient between reconstructed and actual wave fields of up to 0.96-0.97,and a decreased non-dimensional root mean square error(NDRMSE)of around 0.06.The influence of training data on the deep learning model was also studied.Additionally,the impact of the significant wave height and peak period on the CNN model’s accuracy was investigated.It has been demonstrated that the accuracy will fluctuate as the wave steepness increases,but the correlation coefficient remains above 0.90,and the NDRMSE remains less than 0.11.