Synergistic catalysis of the N-hydroxyphthalimide on flower-like bimetallic metal-organic frameworks for boosting oxidative desulfurization

Synergic catalytic effect between active sites and supports greatly determines the catalytic activity for the aerobic oxidative desulfurization of fuel oils.In this work,Ni-doped Co-based bimetallic metal-organic framework(CoNi-MOF)is fabricated to disperse N-hydroxyphthalimide(NHPI),in which the whole catalyst provides plentiful synergic catalytic effect to improve the performance of oxidative desulfurization(ODS).As a bimetallic MOF,the second metal Ni doping results in the flower-like morphology and the modification of electronic properties,which ensure the exposure of NHPI and strengthen the synergistic effect of the overall catalyst.Compared with the monometallic Co-MOF and naked NHPI,the NHPI@CoNi-MOF triggers the efficient activation of molecular oxygen and improves the ODS performance without an initiator.The sulfur removal of dibenzothiophene-based model oil reaches 96.4%over the NHPI@CoNi-MOF catalyst in 8 h of reaction.Furthermore,the catalytic product of this aerobic ODS reaction is sulfone,which is adsorbed on the catalyst surface due to the difference in polarity.This work provides new insight and strategy for the design of a strong synergic catalytic effect between NHPI and bimetallic supports toward high-activity aerobic ODS materials.

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.

Bimetallic Pt–Ru covalently bonded on carbon nanotubes for efficient methanol oxidation

Platinum-based nanocomposites have been considered as one of the most promising catalysts for methanol oxidation reactions(MORs), which yet still suffer from low electrochemical activity and electron-transfer properties. Apart from van-der-Waals heterostructures,herein, we report a novel nanocomposite with the structure of Pt–Ru bimetallic nanoparticles covalently-bonded onto multi-walled carbon nanotubes (MWCNTs)(Pt–Ru@MWCNT), which have been successfully fabricated via a facile and green synthesis method. It is demonstrated that the Pt–Ru@MWCNT nanocomposite possesses much enhanced electrocatalytic activity with the electrochemical active surface area(ECSA) of 110.4 m^(2)·g^(-1)for Pt towards MOR, which is 2.67 and 4.0 times higher than those of 20wt%commercial Pt@C and Pt-based nanocomposite prepared by other method, due to the improved electron-transfer properties originated from M–O–C covalent bonds. This work provides us a new strategy for the structural design of highly-efficient electrocatalysts in boosting MOR performance.

Metal–Oleate Complex?Derived Bimetallic Oxides Nanoparticles Encapsulated in 3D Graphene Networks as Anodes for Efficient Lithium Storage with Pseudocapacitance

In this manuscript, we have demonstrated the delicate design and synthesis of bimetallic oxides nanoparticles derived from metal–oleate complex embedded in 3D graphene networks(MnO/CoMn_2O_4  GN), as an anode material for lithium ion batteries. The novel synthesis of the MnO/CoMn_2O_4  GN consists of thermal decomposition of metal–oleate complex containing cobalt and manganese metals and oleate ligand, forming bimetallic oxides nanoparticles, followed by a selfassembly route with reduced graphene oxides. The MnO/CoMn_2O_4  GN composite, with a unique architecture of bimetallic oxides nanoparticles encapsulated in 3D graphene networks, rationally integrates several benefits including shortening the di usion path of Li^+ ions, improving electrical conductivity and mitigating volume variation during cycling. Studies show that the electrochemical reaction processes of MnO/Co Mn_2O_4  GN electrodes are dominated by the pseudocapacitive behavior, leading to fast Li^+ charge/discharge reactions. As a result, the MnO/CoMn_2O_4  GN manifests high initial specific capacity, stable cycling performance, and excellent rate capability.

Advances in Noble Metal-Decorated Metal Oxide Nanomaterials for Chemiresistive Gas Sensors:Overview

Highly sensitive gas sensors with remarkably low detection limits are attractive for diverse practical application fields including real-time environmental monitoring,exhaled breath diagnosis,and food freshness analysis.Among various chemiresistive sensing materials,noble metal-decorated semiconducting metal oxides(SMOs)have currently aroused extensive attention by virtue of the unique electronic and catalytic properties of noble metals.This review highlights the research progress on the designs and applications of different noble metal-decorated SMOs with diverse nanostructures(e.g.,nanoparticles,nanowires,nanorods,nanosheets,nanoflowers,and microspheres)for high-performance gas sensors with higher response,faster response/recovery speed,lower operating temperature,and ultra-low detection limits.The key topics include Pt,Pd,Au,other noble metals(e.g.,Ag,Ru,and Rh.),and bimetals-decorated SMOs containing ZnO,SnO_(2),WO_(3),other SMOs(e.g.,In_(2)O_(3),Fe_(2)O_(3),and CuO),and heterostructured SMOs.In addition to conventional devices,the innovative applications like photo-assisted room temperature gas sensors and mechanically flexible smart wearable devices are also discussed.Moreover,the relevant mechanisms for the sensing performance improvement caused by noble metal decoration,including the electronic sensitization effect and the chemical sensitization effect,have also been summarized in detail.Finally,major challenges and future perspectives towards noble metal-decorated SMOs-based chemiresistive gas sensors are proposed.

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.

Pt–Pd bimetallic nanoparticles anchored on uniform mesoporous MnO_(2) sphere as an advanced nanocatalyst for highly efficient toluene oxidation

Improving catalytic performance is a yet still challenge in thermal catalytic oxidation.Herein,uniform mesoporous MnO_(2) nanospheresupported bimetallic Pt–Pd nanoparticles were successfully fabricated via a SiO_(2) template strategy for the total catalytic degradation of volatile organic compounds at low temperature.The introduction of mesopores into the MnO_(2) support induces a large specific surface area and pore size,thus providing numerous accessible active sites and enhanced diffusion properties.Moreover,the addition of a secondary noble metal can adjust the O_(ads)/O_(latt) molar ratios,resulting in high catalytic activity.Among them,the catalyst having a Pt/Pd molar ratio of 7:3 exhibits optimized catalytic activity at a weight hourly space velocity of 36,000 mL g^(-1) h^(-1),reaching 100%toluene oxidation at 175℃ with a lower activation energy(57.0 kJ mol^(-1))than the corresponding monometallic Pt or non-Pt-based catalysts(93.8 kJ mol^(-1) and 214.2 kJ mol^(-1)).Our findings demonstrate that the uniform mesoporous MnO_(2) nanosphere-supported bimetallic Pt–Pd nanoparticles catalyst is an effective candidate for application in elimination of toluene.

Bimetallic water oxidation: One-site catalysis with two-sites oxidation

Water oxidation is the key half reaction to achieve full splitting of water to hydrogen and oxygen.Herein,a binuclear complex,[(L^(4-))Co_(2)~Ⅲ(OH)]ClO_(4),was reported as a stable and efficient homogenous catalyst for electrocatalytic water oxidation in 0.1 M phosphate buffer(pH 7.0).Cyclic voltammetry experiments indicated that the catalytic process proceed via "one-site catalysis with two-sites oxidation" mechanism in which both two metal sites store the required oxidation equivalents for water oxidation and O-O bond formation occurs by single-site water nucleophilic attack(WNA).

Pt-Re/rGO bimetallic catalyst for highly selective hydrogenation of cinnamaldehyde to cinnamylalcohol

In the present work, a series of Pt-based catalysts, alloyed with a second metal, i.e., Re, Sn, Er, La, and Y, and supported on activated carbon, ordered mesoporous carbon, N-doped mesoporous carbon or reduced graphene oxide(rGO), have been developed for selective hydrogenation of cinnamaldehyde to cinnamylalcohol. Re and rGO were proved to be the most favorable metal dopant and catalyst support, respectively. Pt_(50) Re_(50)/rGO showed the highest cinnamylalcohol selectivity of 89% with 94% conversion of cinnamaldehyde at the reaction conditions of 120 °C, 2.0 MPaH_2 and 4 h.

Synthesis and catalytic property of Cu-Mn-Ce/γ-Al_2O_3 complex oxide

A new type of catalytic material for purification of automobile exhaust, Cu Mn Ce O/ γ Al 2O 3, has been studied. The factors affecting its catalytic activity, such as calcination temperature and the period of calcinations and so on have been investigated. Its catalytic activity after SO 2 poisoning was determined in a fixed bed reactor by exposing the sample to the atmosphere of 160?mL/min SO 2/air. The study reveals that the catalyst has shown high catalytic activities for the conversion of NH 3 oxidation by NO after sulfate. The conversion of NO reduction over the sulfated catalyst is somewhat higher than that over the fresh catalyst except that the optimum temperature has increased about 100?℃. Also at the optimum process for the experiment, the selective catalytic oxidation of CO by NO is over 76% and the conversion of NO reduction is over 80% by NH 3.

A mechanic insight into low-temperature catalytic combustion toward ethylene oxide over Pt-Ru/CuCeO_(x) bimetallic catalyst

The catalytic oxidation performance toward ethylene oxide(EO)and the consequent mechanism were investigated on the Pt-Ru/CuCeO_(x)bimetallic catalyst,which was prepared by a distinct method combining stepwise adsorption and subsequent impregnation.The catalytic tests show that the introduction of Ru into the Pt catalyst,so as to form Pt-Ru bimetallic active sites,can greatly increase the oxidation activity of the catalyst,as evidenced by the extremely lower full oxidation temperature(120℃)when compared with that of the Pt/CeO_(2) catalyst(160℃).The XPS spectra show that the Ru species(mainly RuO_(x))have strong interaction with the CuCeO_(x) support,which can therefore affect the electron transfer between the Pt species and the support.As a result,the oxygen activation on Pt species is obviously facilitated and catalytic activity is enhanced.Finally,in situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTs)was used to track the reaction mechanism.It is found that the catalytic oxidation process follows the MvK catalytic mechanism at low temperature and the L-H catalytic mechanism when the temperature moves to higher range.

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.

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.

Progress in niobium-based oxides as anode for fast-charging Li-ion batteries

With the increasing popularity of electric/hybrid vehicles and the rapid development of 3C electronics,there is a growing interest in high-rate energy storage systems.The rapid development and widespread adoption of lithiumion batteries(LIBs)can be attributed to their numerous advantages,including high energy density,high operating voltage,environmental friendliness,and lack of memory effect.However,the progress of LIBs is currently hindered by the limitations of energy storage materials,which serve as vital components.Therefore,there is an urgent need to address the development of a new generation of high-rate energy storage materials in order to overcome these limitations and further advance LIB technology.Niobium-based oxides have emerged as promising candidates for the fabrication of fast-charging Li-ion batteries due to their excellent rate capability and long lifespan.This review paper provides a comprehensive analysis of the fundamentals,methodologies,and electrochemistries of niobium-based oxides,with a specific focus on the evolution and creation of crystal phases of Nb_(2)O_(5),fundamental electrochemical behavior,and modification methods including morphology modulation,composite technology,and carbon coating.Furthermore,the review explores Nb_(2)O_(5)-derived compounds and related advanced characterization techniques.Finally,the challenges and issues in the development of niobiumbased oxides for high-rate energy storage batteries are discussed,along with future research perspectives.

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°C,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°C,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°C in 10 min,while the dehydrogenated MgH_(2)took 60 min to absorb only 4.6 wt.%H_(2)at 215°C.The microstructure analysis confirmed that the in-situ generated Mg_(2)Ni/Mg_(2)NiH4 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.

纳米球状LaAlO_(3)的制备及其在酸性条件下的除氟性能

为实现在较低的pH及煅烧温度下合成表面性能良好的LaAlO_(3)晶相,解决废水的深度除氟问题(<1.5mg/L),采用共沉-水热法制备了纳米球状钙钛矿LaAlO_(3),考察了影响LaAlO_(3)表面性能的制备因素,通过SEM(扫描电子显微镜)、XRD(X射线衍射)、ICP-MS(电感耦合等离子体质谱)、BET等分析发现形成碱式碳酸沉淀的水热前体可使Al^(3+)和La^(3+)均匀沉淀、结合紧密,得到LaAlO_(3)的最佳制备条件:共沉淀pH=6,水热温度=160℃,煅烧温度850℃。通过静态吸附实验系统分析了LaAlO_(3)吸附F-的行为,结果表明,LaAlO_(3)可以在酸性(pH<3)条件下实现深度除氟,在pH=2时,除氟效率达到93.22%。吸附过程符合Langmuir等温吸附模型和准二级动力学模型,属于化学单层吸附、放热反应。在初始氟浓度为200mg/L条件下,8min LaAlO_(3)吸附容量达到53.8mg/g,4h平衡吸附容量可达66.5mg/g。以明矾作为脱附剂,LaAlO_(3)能够在循环4次后仍保持原有90%以上的除氟性能,具有良好的再生性能及实际利用价值。

ZnO-CeO_(2)制备及催化性能研究

利用可再生能源产生的绿氢将CO_(2)催化转化为甲醇,是实现碳中和的一条很有前途的路径。CO_(2)加氢制甲醇技术所用到的催化剂是一种ZnO-CeO_(2)双金属氧化物,考察了浸渍法、共沉淀法、沉淀包覆法和物理混合法等制备方法,并采用X射线晶体衍射(XRD)、N_(2)吸附-脱附、二氧化碳程序升温脱附(CO_(2)-TPD)、氢气程序升温脱附(H_(2)-TPD)、扫描电子显微镜(SEM)及X射线光电子能谱(XPS)等表征手段,对ZnO-CeO_(2)双金属氧化物催化剂的物化性质和催化CO_(2)加氢制备甲醇的性能影响进行了分析。结果表明,制备方法对催化剂物化性质和催化性能具有较大的影响。采用共沉淀法制得的ZnO-CeO_(2)催化剂表现出优异的催化性能,在温度为300℃、压力为4 MPa、质量空速为19 600 mL/(g·h)的反应条件下,CO_(2)转化率为4.61%,甲醇选择性达到80.64%,甲醇时空产率达到244.96 mg/(h·g);同时发现拥有丰富的氧空位缺陷浓度、较强H_(2)活化能力、较大比表面积及孔容是该催化剂催化性能提升的关键。

Cu-Ni@S-1催化剂的制备及其脱硝性能

采用溶解-再晶化法将金属Cu和Ni封装到不同粒径的中空Silicalite-1(S-1)分子筛空腔内部,制备了不同金属掺杂量的中空封装型催化剂。采用X射线粉末衍射(XRD)、扫描电子显微镜(SEM)、X射线光电子能谱分析(XPS)等手段对催化剂样品进行了表征,并采用固定床反应器模拟实际工况考察催化剂对催化裂化再生烟气(n(CO)/n(NO)=13/3)中氮氧化物(NO x)的脱除性能。结果表明:在催化剂用量0.15 g、压力0.1 MPa、温度680℃、混合气体积空速60000 mL/(g·h)的条件下,3%Cu@S-1-380的脱硝效率仅为63%,而2%Cu-0.5%Ni@S-1-380的脱硝效率为100%;Ni和Cu之间形成Cu_(x) Ni_(y) O共熔体,促进了Cu^(+)与Cu^(2+)之间快速循环,提高了氧化还原反应速率;催化剂的中空空腔结构有效防止了金属的流失和烧结,极大地提高了反应物的扩散性能和催化剂的催化活性。相同反应条件下,随着分子筛粒径的减小、金属含量的增加,催化剂的脱硝率提高,双金属共同封装对催化活性的提高非常显著。

纳米片状CuCo_(2)O_(4)的合成及析氧性能研究

调控催化剂形貌和结构,优化表面特性,是提高催化性能的重要策略.通过水热合成铜钴双氢氧化物(CuCo LDH)前驱体,再经高温热解制得交叉连接片状CuCo_(2)O_(4)催化剂.该催化剂的粗糙表面和片层间隙有利于电解质的充分扩散吸附;其表面O缺陷能调节相邻金属位点价态,并能提高导电性,适合用于电化学催化.优化元素组成所制备CuCo_(2)O_(4)-1具有良好碱性析氧反应(OER)催化活性,在1 mol·L^(-1)KOH电解质中,电流密度为100 mA·cm^(-2)时的过电位(η)为362 mV,OER塔菲尔斜率为112.2 mV·dec^(-1),经过50 h的计时电位测试,η保持稳定,也显示出良好催化稳定性。为碱性OER电催化剂的设计提供了可行方案.

Amorphous hybrid tungsten oxide–nickel hydroxide nanosheets used as a highly efficient electrocatalyst for hydrogen evolution reaction

There are more challenges for alkaline hydrogen evolution reaction(HER)via simultaneously expediting the electron-coupled water dissociation process(Volmer step)and the following electrochemical H_(2) desorption(Heyrovsky step).Hybrid amorphous electrocatalysts are highly desirable for efficient hydrogen evolution from water-alkali electrolyzers due to the bifunctionality for the different elementary steps of HER and optimal interactions with water molecules and the reactive hydrogen intermediates(Had).Herein,the synthesis of amorphous hybrid ultrathin(tungsten oxide/nickel hydroxide)hydrate(a-[WO_(3)/Ni(OH)_(2)]·0.2H_(2)O)nanosheets on nickel foam(NF)for efficient alkaline HER is described.The structural and composition features of a-[WO_(3)/Ni(OH)_(2)]·0.2H_(2)O are characterized in detailed.The resulting a-[WO_(3)/Ni(OH)_(2)]·0.2H_(2)O/NF electrocatalyst with the synergistic effect of both hybrid components for the HER elementary steps shows greatly improved the activity and durability for the HER with a low overpotential of-41 and-163 mV at-10 and-500 mA·cm^(-2),respectively,a Tafel slope as low as-72.9 mV·dec^(-1),and long-term stability of continuous electrolysis for at least 150 h accompanying by inappreciable overpotential change in 1 M KOH.In the hybrid a-[WO_(3)/Ni(OH)_(2)]·0.2H_(2)O,Ni(OH)_(2) and WO_(3) moieties are separately responsible for accelerating dissociative adsorption of water and weakening Had adsorption strength,which is beneficial to the improvement of the alkaline HER activity.