Phase separation-hydrogen etching-derived Cu-decorated Cu-Mn bimetallic oxides with oxygen vacancies boosting superior sodium-ion storage kinetics

Understanding the crystal phase evolution of bimetallic oxide anodes is the main concern to profoundly reveal the conversion reaction kinetics and sodium-ion storage mechanisms.Herein,an integrated selfsupporting anode of the Cu-decorated Cu-Mn bimetallic oxides with oxygen vacancies(Ov-BMO-Cu)are in-situ generated by phase separation and hydrogen etching using nanoporous Cu-Mn alloy as selfsacrificial templates.On this basis,we have elucidated the relationship between the phase evolution,oxygen vacancies and sodium-ion storage mechanisms,further demonstrating the evolution of oxygen vacancies and the inhibition effect of manganese oxides as an“anchor”on grain aggregation of copper oxides.The kinetic analyses confirm that the expanded lattice space and increased oxygen vacancies of cycled Ov-BMO-Cu synergistically guarantee effective sodium-ion diffusion and storage mechanisms.Therefore,the Ov-BMO-Cu electrode exhibits higher reversible capacities of 4.04 mA h cm^(-2)at 0.2 mA cm^(-2)after 100 cycles and 2.20 m A h cm^(-2)at 1.0 mA cm^(-2)after 500 cycles.Besides,the presodiated Ov-BMO-Cu anode delivers a considerable reversible capacity of 0.79 m A h cm^(-2)at 1.0 mA cm^(-2)after 60 cycles in full cells with Na_(3)V_(2)(PO_(4))_(3)cathode,confirming its outstanding practicality.Thus,this work is expected to provide enlightenment for designing high-capacity bimetallic oxide anodes.

Heterogeneous bimetallic oxides/phosphides nanorod with upshifted d band center for efficient overall water splitting

Electrocatalytic water splitting is the most directly available route to generate renewable and sustainable hydrogen.Here,we report the design of a composite material in which arrays of square pillar-like NiMoO4nanorods coated with N,P-doped carbon layers are uniformly contained in numerous nested nanoparticle structures.The catalysts have superior catalytic activity,requiring only 59 mV and 187 mV for HER and OER to attain a current density of 10 mA/cm^(2),respectively.The assembled two-electrode electrolytic cell required a voltage of 1.48 V to reach 10 mA/cm^(2),along with excellent long-term stability.Theoretical calculations reveal that electrons aggregate and redistribute at the heterogeneous interface,with the d-band centers of the Ni and Fe atoms being positively shifted compared to the Fermi level,effectively optimizing the adsorption of intermediates and reducing the Gibbs free energy,thus accelerating the catalytic process.Meanwhile,an integrated solar-driven water-splitting system demonstrated a high and stable solar-to-hydrogen efficiency of 18.20%.This work provides new possibilities for developing non-precious metal-based bifunctional electrocatalysts for large-scale water splitting applications.

Enhanced activation of persulfate using mesoporous silica spheres augmented Cu–Al bimetallic oxide particles for bisphenol A degradation

Herein,Cu–Al bimetallic oxide was synthesized and mixed with mesoporous silica spheres via a simple hydrothermal method.The prepared sample was then analyzed and employed to activate potassium peroxydisulfate for bisphenol A removal.Based on the results of X-ray diffraction,scanning electron microscopy,and energy dispersion spectroscopy,Cu–Al bimetallic oxide was determined as CuO-Al2O3,and mesoporous silica spheres were found around the these particles.At 30 min,a bisphenol A degradation level of 90%was achieved,and it remained at over 60%after five consecutive cycles,indicating the catalyst’s superior capacity and stability.In terms of removal performance,the radical pathway(including■OH•,and■)and singlet oxygen(■)bisphenol A,potassium peroxydisulfate,and the catalyst played a dominant role.The introduction of Al2O3 promoted the formation of surface oxygen vacancies,which improved ligand complex formation between potassium peroxydisulfate and the catalyst,thereby facilitating electron migration.Furthermore,mesoporous silica spheres augment not only enhanced bisphenol A adsorption but also alleviated Cu leaching.Overall,this work is expected to provide significant support for the rational development of catalysts with high catalytic activity for persulfate activation via surface electron migration.

Graphene-loaded nickel−vanadium bimetal oxides as hydrogen pumps to boost solid-state hydrogen storage kinetic performance of magnesium hydride

To modify the thermodynamics and kinetic performance of magnesium hydride(MgH_(2))for solid-state hydrogen storage,Ni_(3)V_(2)O_(8)-rGO(rGO represents reduced graphene oxide)and Ni_(3)V_(2)O_(8)nanocomposites were prepared by hydrothermal and subsequent heat treatment.The beginning hydrogen desorption temperature of 7 wt.%Ni_(3)V_(2)O_(8)-rGO modified MgH_(2)was reduced to 208℃,while the additive-free MgH_(2)and 7 wt.%Ni_(3)V_(2)O_(8)doped MgH_(2)appeared to discharge hydrogen at 340 and 226℃,respectively.A charging capacity of about 4.7 wt.%H_(2)for MgH_(2)+7 wt.%Ni_(3)V_(2)O_(8)-rGO was achieved at 125℃ in 10 min,while the dehydrogenated MgH_(2)took 60 min to absorb only 4.6 wt.%H_(2)at 215℃.The microstructure analysis confirmed that the in-situ generated Mg_(2)Ni/Mg_(2)N_(i)H_(4) and metallic V contributed significantly to the enhanced performance of MgH_(2).In addition,the presence of rGO in the MgH_(2)+7 wt.%Ni_(3)V_(2)O_(8)-rGO composite reduced particle aggregation tendency of Mg/MgH_(2),leading to improving the cyclic stability of MgH_(2)during 20 cycles.

Bimetallic oxide coupled with B-doped graphene as highly efficient electrocatalyst for oxygen evolution reaction

Developing electrocatalysts with high performance and low cost for the oxygen evolution reaction(OER)is of great importance for fabricating renewable energy storage and conversion devices.Here,a series of boron-doped graphene(BG)-supported bimetallic oxides of Co and Ni were obtained and served as OER electrocatalysts.Surprisingly,the annealed Co-Ni-Ox/BG with a Co/Ni ratio of 1:1 exhibits high performance toward oxygen evolution in alkaline electrolyte.The overpotential is only 310 mV at the current density of 10 mA cm-2,superior to many mono-metallic oxides reported before,and even comparable to the commercial RuO2.The regulation of charge distribution in bimetallic oxides and the strong synergistic coupling effects together contribute to the superior electrocatalytic performance of the Co-Ni-Ox/BG toward OER.This study also offers several effective ways to design high-performance OER electrocatalysts for water splitting.

Base-free aerobic oxidation of glycerol on TiO_2-supported bimetallic Au–Pt catalysts

The aerobic oxidation of glycerol provides an economically viable route to glyceraldehyde, dihydroxyacetone and glyceric acid with versatile applications, for which monometallic Pt, Au and Pd and bimetallic Au-Pt, Au- Pd and Pt-Pd catalysts on TiO2 were examined under base-free conditions. Pt exhibited a superior activity relative to Pd, and Au-Pd and Pt-Pd while Au was essentially inactive. The presence of Au on the Au-Pt/TiO2 catalysts led to their higher activities （normalized per Pt atom） in a wide range of Au/Pt atomic ratios （i.e. 1/3-7/1 ）, and the one with the Au/Pt ratio of 3/1 exhibited the highest activity. Such promoting effect is ascribed to the increased electron density on Pt via the electron transfer from Au to Pt, as characterized by the temperature-programmed desorption of CO and infra-red spectroscopy for CO adsorption. Meanwhile, the presence of Au on Au-Pt/TiO2, most like due to the observed electron transfer, changed the product selectivity, and facilitated the oxidation of the secondary hydroxyl groups in glycerol, leading to the favorable formation of dihydroxyacetone over glyceraldehyde and glyceric acid that were derived from the oxidation of the primary hydroxyl groups. The synergetic effect between Au and Pt demonstrates the feasibility in the efficient oxidation of glycerol to the targeted products, for example, by rational tuning of the electronic properties of metal catalysts.

A hierarchically structured tin-cobalt composite with an enhanced electronic effect for high-performance CO_(2) electroreduction in a wide potential range

Earth-abundant and nontoxic Sn-based materials have been regarded as promising catalysts for the electrochemical conversion of CO_(2)to C1 products,e.g.,CO and formate.However,it is still difficult for Snbased materials to obtain satisfactory performance at low-to-moderate overpotentials.Herein,a simple and facile electrospinning technique is utilized to prepare a composite of a bimetallic Sn-Co oxide/carbon matrix with a hollow nanotube structure(Sn Co-HNT).Sn Co-HNT can maintain>90%faradaic efficiencies for C1 products within a wide potential range from-0.6 VRHE to-1.2 VRHE,and a highest 94.1%selectivity towards CO in an H-type cell.Moreover,a 91.2%faradaic efficiency with a 241.3 m A cm^(-2)partial current density for C1 products could be achieved using a flow cell.According to theoretical calculations,the fusing of Sn/Co oxides on the carbon matrix accelerates electron transfer at the atomic level,causing electron deficiency of Sn centers and reversible variation between Co^(2+)and Co^(3+)centers.The synergistic effect of the Sn/Co composition improves the electron affinity of the catalyst surface,which is conducive to the adsorption and stabilization of key intermediates and eventually increases the catalytic activity in CO_(2)electroreduction.This study could provide a new strategy for the construction of oxide-derived catalysts for CO_(2)electroreduction.

Heterogeneously-catalyzed aerobic oxidation of furfural to furancarboxylic acid with CuO-Promoted MnO_(2)

A cost-effective and sustainable noble-metal free catalyst system based on ubiquitously available Mn-Cu bimetallic oxides was served as efficient catalysts for furfural selective oxidation to furancarboxylic acid(FA). Interestingly, Mn_(2)Cu_(1)O_(x)exhibited an excellent furfural conversion of 99% with quantitative selectivity toward FA. Especially, we demonstrate the significant weakening of the Mn-O bonds with the incorporation of CuO into the Mn-Cu oxides, resulting in an improved OLreactivity of Mn_(2)Cu_(1)O_(x), which brings about a higher catalytic activity for furfural oxidation. More importantly, Mn_(2)Cu_(1)O_(x)could exhibit YFA>90% over 5 cycles of reusability test. Through this study, the relationship between the morphology, surface chemistry, and catalytic activity of Mn-Cu bimetallic oxides are elucidated, providing a simple and environmentally friendly catalytic strategy and scientific basis for the development of Mn-Cu bimetallic oxides bioderived molecular aerobic oxidation materials.

Hydrothermal Synthesis and Structure of a Mixed-valence Polyoxotungstate Decorated by Copper(I) Coordination Group, [Cu(en)_2H_2O]_2[{Cu(en)_2}HPW_(12)O_(40)]·2H_2O

A complex [Cu(en)2H2O]2[{Cu(en)2}HPW12O40]?2H2O (C12H57Cu3N12O44PW12, Mr = 3501.49) has been synthesized under hydrothermal conditions and its crystal structure was determined by X-ray diffraction. It crystallizes in the orthorhombic system, space group Pbca with a = 21.680(4), b = 20.680(4), c = 26.120(5) ?, V = 11711(4) ?3, Dc = 3.972 g/cm3, Z = 8, μ(MoKa) = 24.661 mm?1, F(000) = 12440, the final R = 0.0527 and wR = 0.1416 for 11527 observed reflec- tions with I > 2σ(I). The crystal structure is composed of [{Cu(en)2}HPW12O40]2? anions, discrete [Cu(en)2H2O]+ complex cations and crystal water molecules, which are held together into a three- dimensional network through hydrogen-bonding interactions. The anionic [{Cu(en)2}HPW12O40]2? is formed by the mixed valance {HPWVI11WVO40}3? Keggin unit covalently linked by a {Cu(en)2}+ group.

Heterobimetallic CoCeO_(x) derived from cobalt partially-substituted Ce-UiO-66 for chlorobenzene efficient catalytic destruction

Here,a metal-organic framework(MOF)-templated strategy was applied to synthesize the CoCeO_(x) bimetallic catalysts by calcining Co partially-substituted Ce-UiO-66.It is indicated that the substituted Co limited Ce cations in Ce-UiO-66 framework,which affects its growth and structure crystallinity to some extent.After pyrolysis treatment,the derived bimetallic oxide(CoCeO_(x)-M)can basically keep the octahedral structure and the surface area is much higher than the bulk metal composite oxide(CoCeO_(x)-B)prepared by traditional coprecipitation.Results reveal that CoCeO_(x)-M performs the best chlorobenzene degradation capacity,superior stability and vapor tolerance compared with those of CeO_(2)-M(derived from Ce-UiO-66)and CoCeO_(x)-B.At the same time,it is favorable to inhibit the formation of CO during the oxidation reaction.The superior catalytic performance of CoCeO_(x)-M is attributed to a good dispersion of metal cations,high surface area and active oxygen concentration,and good redox property.Moreover,the formation of organic byproducts especially chlorinated organics can be obviously prohibited over CoCeO_(x)-M compared with that of CeO_(2)-M.Mechanism study reveals that chlorobenzene dissociates on the surface of CoCeO_(x)-M to form carboxylates such as acetate species,maleate and phenolate before finally oxidized into CO_(2),H_(2)O,and HCl.The present work poses new insights into the fabrication of efficient catalysts for industrial CVOC purification.

Rare earth metal as a dopant element:Cerium ion as an articulator in hexavalent chromium removal by magnetic iron oxides

This study highlights introducing the rare earth metal cerium(Ce(Ⅳ))into the structure of magnetite(Fe_(3)O_(4))to achieve enhanced adsorptive properties for the removal of chromium(Cr(VI))from an aqueous medium.Different ratios of Ce(Ⅳ)were introduced into the iron oxide matrix,termed FeCe-5,FeCe-10,and FeCe-20.Their numerical values correspond to the nominal content of the dopant element added to the synthesis medium.The solid materials were characterized for morphology and chemical structure,and N_(2)physical adsorption/desorption measurements were performed.The solid materials doped with Ce(IV)have a high surface area compared to Fe_(3)O_(4),and the solid material with the highest content of the dopant ion(Ce(IV))has a 4-fold greater surface area.This increase in the dopant content in the iron oxide structure leads to a total chromium removal of 93.3%.Isotherms studies on the solid materials show that chromium adsorption follows the Langmuir model.The adsorption capacity to Fe_(3)O_(4)is 12.59 mg/g and FeCe-10 is 22.49 mg/g at 35℃.By fitting the kinetic and isothermal models,it is found that for the Fe_(3)O_(4)and FeCe-10 materials Cr(VI)removal occurs in very different ways,attributed to the different surface areas and compositions of the oxide,with the formation of the goethite(α-FeOOH)phase.The FeCe-10reuse process was performed and the removal capacity the Cr(VI)is reduced after the first cycle.This result is attributed to a strong and irreversible adsorption of Cr(VI)on the FeCe-10.

Core-shell structured Ru-Ni@SiO_2: Active for partial oxidation of methane with tunable H_2/CO ratio

This study demonstrated that a Ru-Ni bimetallic core-shell catalyst（0.6%Ru-Ni）@Si O2with a proper surface Ru concentration is superior in achieving better catalytic activity and tunable H2/CO ratio at a comparatively lower reaction temperature（700℃）.Compared to the impregnation method,the hydrothermal approach leads to a highly uniform Ru distribution throughout the core particles.Uniform Ru distribution would result in a proper surface Ru concentration as well as more direct Ru-Ni interaction,accounting for better catalyst performance.Enriched surface Ru species hinders surface carbon deposition,but also declines overall activity and H2/CO ratio,meanwhile likely enhances Ni oxidation to certain degree under the applied reaction conditions.Over the current（m%Ru-Ni）@Si O2catalyst,the formation of fibrous carbon species is suppressed,which accounts for good stability of catalyst within a TOS of 10 h.

Enhanced heterogeneous activation of peroxymonosulfate by boosting internal electron transfer in a bimetallic Fe_(3)O_(4)-MnO_(2) nanocomposite

Transition metal-based bimetallic oxides can effectively activate peroxymonosulfate(PMS) for the degradation of organic contaminants, which may be attributed to the enhanced electron transfer efficiency between transition metals. Here, we investigated the high-efficiency catalytic activation reaction of PMS on a well-defined bimetallic Fe-Mn nanocomposite(BFMN) catalyst. The surface topography and chemical information of BFMN were simultaneously mapped with nanoscale resolution. Rhodamine B(Rh B, as a model pollutant) was used to evaluate the oxidation activity of PMS activation system. The maximum absorption peak of Rh B obviously blue shifted from 554 nm to 501 nm, and decreased sharply to disappear completely within 60 min. The removal performance is better than most of the reported single transition metal oxide. X-ray photoelectron spectroscopy(XPS) imaging of the BFMN electronic structure after catalytic activation confirmed that the accelerated internal electron transfer is mainly caused by the synergy effect of Mn and Fe sites at the catalysis boundary. The outstanding ability of BFMN for PMS chemical adsorption and activation may attribute to the enhanced covalency and reactivity of Mn-O. These results of this study can advance understandings on the origins of bimetallic oxides activity for PMS activation and developing the efficient metal oxide catalysts in real practice.

Mixed matrix membrane containing metal oxide nanosheets for efficient CO_(2)separation

The two-dimensional(2D)nanosheet zinc cobaltate(ZnCo_(2)O_(4))was added into polyether block amide(Pebax)matrix to prepare mixing matrix membrane(MMM)for separating carbon dioxide(CO_(2))/methane(CH4)gas mixture.The 2D porous ZnCo_(2)O_(4)nanosheets were composed of chemically interconnected metal oxide nanoparticles.The ZnCo_(2)O_(4)nanoparticles in the nanosheets constructed large-quantity pores of 11.78 nm and provided abundant transfer channels for gas molecule.Moreover,the synergistic effect of bimetallic Zn^(2+)and Co^(2+)would promote the generation of oxygen vacancies(Oδ-),which could provide more CO_(2)(Cδ+)adsorption sites,thereby increased the selectivity of the membrane.The large aspect ratio of the ultra-thin ZnCo_(2)O_(4)nanosheets showed better dispersion in the membrane.The pure gas separation performance data showed the CO_(2)permeability and CO_(2)/CH4 selectivity of Pebax/ZnCo_(2)O_(4)membrane were 139.10 Barrer and 15.38,respectively,when the filling amount was 0.5 wt%.Compared with pure Pebax membrane,the separation performance(permeability and selectivity)were increased with 165.67%and 75.57%,respectively.

Co-Fe quantum dots coupled with ultrathin g-C_(3)N_(4) nanosheets as efficient and stable photo-Fenton catalysts

The Fenton reaction has been widely used in the environmental remediation.However,the sharp decline of photo-Fenton catalysts activity under neutral conditions is still an urgent problem to be solved.This study reports a Co/Fe bimetallic oxide quantum dots-coupled g-C_(3)N_(4)nanosheets(CoFeO QDs/g-C_(3)N_(4) NSs) composites with efficient degradation of organic pollutants under neutral conditions.Under the photo-Fenton condition,rhodamine B(RhB) degradation efficiency reached 98.32% within 90min for CoFeO QDs/g-C_(3)N_(4) NSs composites.The formed heterojunction between CoFeO QDs and g-C_(3)N_(4) NSs achieves enhanced charge transfer and efficient charge separation.Co-Fe bimetals make g-C_(3)N_(4) NSs easier to excite the production of·OH by H_(2)O_(2),achieving excellent degradation efficiency and cycle stability for organic pollutants in a wide pH range.Therefore,CoFeO QDs/g-C_(3)N_(4)NSs composites can be used as efficient and stable photoFenton catalysts to degrade organic contaminants in practical applications.

Rational construction of hollow nanoboxes for long cycle life alkali metal ion batteries

Hollow nanostructures are extremely attractive in energy storage and show broad application prospects.But the preparation method is accompanied by a complicated process.In this article,the CoZn-based hol-low nanoboxes with electrochemical synergy are prepared in a simple way.This structure can effectively shorten the transmission distance of ions and electrons,and alleviate the volume expansion during the cycle.In particular,bimetallic oxides are rich in oxygen vacancies,providing more active sites for electro-chemical reactions.In addition,the stepwise oxidation-reduction reaction can also improve the volume change of the electrode material.According to the kinetic analysis and density functional theory(DFT)calculation,it is confirmed that the synergistic effect of the bimetallic oxide can accelerate the reaction kinetics.Based on these characteristics,the electrode exhibits stable cycle performance and long cycle life in alkali metal ion batteries,and can provide reversible capacities of 302.1(LIBs,2000 cycles),172.5(SIBs,10000 cycles)and 109.6(PIBs,5000 cycles)mA h g^(-1)at a current density of 1.0 A g^(-1),respectively.In ad-dition,by assembling(LiCoO_(2)//CoZn-O_(2))and(Na_(3)V_(2)(PO_(4))_(3)//CoZn-O_(2))full-cells,the practical application value is demonstrated.The sharing of this work introduces a simple way to synthesize hollow nanoboxes,and shows excellent electrochemical performance,which can also be expanded in other areas.

Phase Engineering of CoMo0_(4)Anode Materials toward Improved Cycle Life for Li^(+)Storage

Anode materials based on conversion reactions usually possess high energy densities for lithium-ion batteries(LIBs).However,they suffer from poor rate performance and cycle life due to serious volume changes.Herein,α/β-CoMo04 heterogeneous nanorods are synthesized via a facile co-precipitation method,and further are phase-engineered through varying calcination temperature,accomplishing the obviously improved cycle life and rate performance as anodes for LIBs.When evaluated at a current density of 1.0 A·g^(-1)the optimal nanorods with anα/βphase ratio of 6.0 afford the reversible capacity of 1143.6 mAh·g^(-1)after 200 cycles,outperforming most of recently reported bimetal oxides.Li^(+)storage mechanism is further analyzed by using in-situ X-ray diffraction and ex-situ transition electronic microscopy.It's revealed thatβ-CoMoO_(4)follows a one-step conversion reaction;whileα-CoMo0_(4)proceeds an intercalation pathway before the conversion reaction.Grading storage of Li^(+)would alleviate the volume effect of heterostructuredα/β-CoMo0_(4),forming electronically conductive network evenly composed of Co and Mo nanograins to enable the reversible electrochemical conversion.This work is anticipated to give some hints for the rational design of high-performance energy materials.

Effect of Al22Si/ZL102 bimetal interface fabricated by extrusion at neareutectic temperature

The Al22Si/ZL102 bimetal was designed and prepared by extrusion at near-eutectic temperature.The properties and fracture behaviors of different surface treatments between oxide film and zinc coating were compared between the Al22 Si and ZL102 bimetal.The average bonding strength of bimetal with intermittent oxide film interface was about 89.3MPa,which is higher than that of the bimetal fabricated by zinc coating method（about 76.3MPa）.During the process of extrusion,the oxidation film was extruded to crush and the metal was extruded through the micro-cracks of the oxidation film,then the two surfaces were joined together.Altogether,the results showed that extrusion at near-eutectic temperature is favorable for achieving a high-quality metallurgical bonded interface.