Trimetallic Metal-Organic Framework Nanoframe Superstructures: A Stress-Buffering Architecture Engineering of Anode Material toward Boosted Lithium Storage Performance

Metal-organic frameworks(MOFs)can serve as prevailing anodes for lithium-ion batteries,due to their multiple redox-active sites and prominent structural compatibility.However,the poor electronic conductivity and inferior cyclability hinder their further implementation.Herein,a synthetic methodology for trimetallic Fe-Co-Ni MOFs with nanoframe superstructures architecture(Fe-Co-Ni NFSs)via structural evolution is proposed for versatile anode materials for lithium storage.Ascribed to optimal compositional and structural optimization,the Fe-Co-Ni NFSs achieve exceptional electrochemical performance with superior specific capacity(1030 mAh g^(−1) at 0.1 A g^(−1)),outstanding rate capacity(414 mAh g^(−1) at 2 A g^(−1)),and prolonged cyclability(489 mAh g^(−1) upon 1000 cycles at 1 A g^(−1)).Both experimental and theoretical investigations reveal that the multi-component metal centers could boost electronic conductivity,confer multiple active sites,and energetically favor Li adsorption capability.Additionally,the nanoframe superstructures of Fe-Co-Ni NFSs could facilitate stress-buffering effect on volumetric expansion and prevent electrode pulverization,further improving the lithium storage capability.This work envisions a meticulous protocol for high-performance MOF anode materials for lithium-ion batteries.

Reduced graphene oxide supported Pd-Cu-Co trimetallic catalyst:synthesis,characterization and methanol electrooxidation properties

Trimetallic palladium-copper-cobalt nanoparticles supported on reduced graphene oxide(PdCuCo/RGO)with different molar ratios of Pd,Cu and Co can be synthesized by facile chemical reduction with NaBH_4 as reductant and cetrimonium bromide as stabilizer.The morphology,structure and composition of the as-synthesized catalysts are characterized by transmission electron microscopy,X-ray diffraction and Xray photoelectron spectroscopy.The cyclic voltammetry and chronoamperometry are utilized to investigate the electrochemical activities and stabilities of the as-obtained catalysts.The results demonstrate that the PdCuCo/RGO catalyst shows superior catalytic activity and stability for methanol electrooxidation in alkaline media compared with PdCu/RGO,PdCo/RGO,and Pd/RGO catalysts.These findings suggest that the PdCuCo/RGO catalyst possesses a great potential as a promising anode catalyst for direct methanol fuel cells.

Synergistic Effects in CNTs-PdAu/Pt Trimetallic Nanoparticles with High Electrocatalytic Activity and Stability

We present a straightforward physical approach for synthesizing multiwalled carbon nanotubes(CNTs)-Pd Au/Pt trimetallic nanoparticles(NPs), which allows predesign and control of the metal compositional ratio by simply adjusting the sputtering targets and conditions. The small-sized CNTs-Pd Au/Pt NPs(~3 nm, Pd/Au/Pt ratio of 3:1:2) act as nanocatalysts for the methanol oxidationreaction(MOR), showing excellent performance with electrocatalytic peak current of 4.4 A mg^(-1) Pt and high stability over 7000 s. The electrocatalytic activity and stability of the Pd Au/Pt trimetallic NPs are much superior to those of the corresponding Pd/Pt and Au/Pt bimetallic NPs,as well as a commercial Pt/C catalyst. Systematic investigation of the microscopic, crystalline, and electronic structure of the Pd Au/Pt NPs reveals alloying and charge redistribution in the Pd Au/Pt NPs, which are responsible for the promotion of the electrocatalytic performance.

Hydrogen evolution-assisted one-pot aqueous synthesis of hierarchical trimetallic PdNiRu nanochains for hydrazine oxidation reaction

A hydrogen evolution-assisted one-pot aqueous approach was developed for facile synthesis of trimetallic Pd Ni Ru alloy nanochain-like networks（Pd Ni Ru NCNs） by only using KBHas the reductant, without any specific additive（e.g. surfactant, polymer, template or seed）. The products were mainly investigated by transmission electron microscopy（TEM）, X-ray diffraction（XRD） and X-ray photoelectron spectroscopy（XPS）. The hierarchical architectures were formed by the oriented assembly growth and the diffusioncontrolled deposition in the presence of many in-situ generated hydrogen bubbles. The architectures had the largest electrochemically active surface area（ECSA） of 84.32 mgPdthan Pd Ni nanoparticles(NPs,65.23 mgPd), Pd Ru NPs(23.12 mgPd), Ni Ru NPs（nearly zero）, and commercial Pd black(6.01 mgPd), outperforming the referenced catalysts regarding the catalytic characters for hydrazine oxygen reaction（HOR）. The synthetic route provides new insight into the preparation of other trimetallic nanocatalysts in fuel cells.

Trimetallic nanostructures and their applications in electrocatalytic energy conversions

The advancement and growth of nanotechnology lead to realizing new and novel multi-metallic nanostructures with well-defined sizes and morphology,resulting in an improvement in their performance in various catalytic applications.The trimetallic nanostructured materials are synthesized and designed in different architectures for energy conversion electrocatalysis.The as-synthesized trimetallic nanostructures have found unique physiochemical properties due to the synergistic combination of the three different metals in their structures.A vast array of approaches such as hydrothermal,solvothermal,seedgrowth,galvanic replacement reaction,biological,and other methods are employed to synthesize the trimetallic nanostructures.Noteworthy,the trimetallic nanostructures showed better performance and durability in the electrocatalytic fuel cells.In the present review,we provide a comprehensive overview of the recent strategies employed for synthesizing trimetallic nanostructures and their energy-related applications.With a particular focus on hydrogen evolution,alcohol oxidations,oxygen evolution,and others,we highlight the latest achievements in the field.

Precious trimetallic single-cluster catalysts for oxygen and hydrogen electrocatalytic reactions:Theoretical considerations

Single cluster catalysts(SCCs),which exhibit remarkable catalytic performance due to their high metal loading and synergy effect between metal atoms,have attracted great attention in research.Herein,by means of density functional theory calculations,the oxygen reduction reaction(ORR),oxygen evolution reaction(OER),hydrogen evolution reaction(HER)performances of precious metal(Pt,Pd,Rh,Ir)trimetallic single-cluster electrocatalyst(U_(x)V_(y)W_(z)-NG)are investigated.The calculation results show that Pt,Pd,Ir have significant effect on ORR,OER,HER,respectively,all the calculated U_(x)V_(y)W_(z)-NG structures are thermodynamically stable due to the negative formation energies and binding energies.The Pt_(3)-NG,Pd_(3)-NG,Ir_(3)-NG show the lowest ORR,OER,HER overpotentials of 0.63,0.77,−0.02 V,respectively,among all combinations of U_(x)V_(y)W_(z)-NG.These overpotentials are lower than that of precious metal single atom catalysts(SACs),which indicate better activities of precious trimetallic SCCs than those of SACs.The electronic structure reveals that the O-2p orbital shows strong hybridization strength with Pt-3d orbitals in the system of OH adsorbed Pt_(3)-NG and thus facilitates the electrocatalytic reactions.The results are helpful for the rational design of high-performance triatomic catalysts.

Trimetallic PtRhNi alloy nanoassemblies as highly active electrocatalyst for ethanol electrooxidation

Although nanostructures based on noble metal alloys are widely utilized in （electro）catalysis, their low-temperature synthesis remains an enormous challenge due to the different Nernst equilibrium potentials of metal precursors. Herein, we describe the successful synthesis of trimetallic PtRhNi alloy nanoassemblies （PtRhNi-ANAs） with tunable Pt/Rh ratios using a simple mixed cyanogel reduction method and provide a detailed characterization of their chemical composition, morphology, and structure. Additionally, the electrochemical properties of PtRhNi-ANAs are examined by cyclic voltammetry, revealing composition- dependent electrocatalytic activity in the ethanol oxidation reaction （EOR）. Compared to a commercial Pt black electrocatalyst, optimized Pt3Rh1Ni2-ANAs display remarkably enhanced EOR electrocatalytic performance in alkaline media.

Trimetallic Au@PdPb nanowires for oxygen reduction reaction

The development of highly efficient and stable Pd-based catalysts is crucial to improve their sluggish oxygen reduction reaction(ORR)kinetics in acid media.To improve ORR activity and utilization efficiency of Pd,an ideal catalyst should have ORR-favorable chemical environment,optimized geometric structure,and long periods of operation.In this work,we first synthesize a novel trimetallic Au@PdPb core–shell catalyst consisting of PdPb alloy nano-layers grown on the surface of ultrathin Au nanowires(NWs)by a two-step water-bath method.The Au@PdPb NWs have the merits of anisotropic one-dimensional nanostructure,high utilization efficiency of Pd atoms and doping of Pb atoms.Because of the structural and multiple compositional advantages,Au@PdPb NWs exhibit remarkably enhanced ORR activity with a high haIf-wave potential(0.827 V),much better than those of commercial Pd black(0.788 V)and bimetallic Au@Pd NWs(0.803 V).Moreover,Au@PdPb NWs display better electrocatalytic stability for the ORR than those of Pd black and Au@Pd NWs.This study demonstrates the validity of our approach for deriving highly ORR-active Pd-based catalysts by modifying their structure and composition.

Simultaneous formation of trimetallic Pt-Ni-Cu excavated rhombic dodecahedrons with enhanced catalytic performance for the methanol oxidation reaction

Multimetallic Pt-based alloys with excavated structures have attracted great interest owing to their compositional and morphological tunability, high specific surface areas, and impressive electro-catalytic activities. Herein, we report the first facile one-pot synthesis of trimetallic Pt-Ni-Cu highly excavated rhombic dodecahedrons （ERDs） with a yield approaching 100%. More importantly, these highly uniform nanocrystals have three-dimensionally accessible excavated surfaces, where abundant stepped atoms are observed. Benefiting from the highly excavated rhombic dodecahedral structures, electronic and synergistic effects within the trimetallic allo3~ and abundant stepped atoms, the as-prepared trimetallic Pt-Ni-Cu ERDs exhibit an enhanced electro-catalytic performance for the electro-oxidation of methanol compared to commercial Pt/C and bimetallic Pt-Cu ERDs and Pt-Ni-Cu solid rhombic dodecahedrons solid rhombic dodecahedrons （SRDs）.

Trimetallic FeCoNi disulfide nanosheets for CO_(2)-emission-free methanol conversion

The electrocatalytic methanol conversion is of importance in direct methanol fuel cell,biomass reform-ing,and hydrogen generation.To achieve a“carbon-neutral”target,CO_(2)byproducts derived from biofuels should be mitigated.In contrast to the complete oxidation of methanol to CO_(2),the selective oxidation of methanol to formate is a CO_(2)-emission-free route without the generation of toxic CO intermediates.Herein,we present a highly active catalyst based on transition-metal disulfide nanosheet arrays sup-ported on Ni foam for methanol conversion.Through composition screening,we find that the FeCoNi disulfide nanosheet exhibits a highly efficient and selective methanol-to-formate conversion.The surface reconstruction of this catalyst allows us to produce 0.66 mmol cm^(−2)h^(−1)of formate at low potential(1.40 V)with high faradaic efficiency of>98%.This work offers a substantial composition tuning strat-egy to construct noble-metal-free active multi-metal sites for CO_(2)-emission-free conversion of methanol to value-added formate.

A general bottom-up synthesis of CuO-based trimetallic oxide mesocrystal superstructures for efficient catalytic production of trichlorosilane

Mesocrystals, the non-classical crystals with highly ordered nanoparticle superstructures, have shown great potential in many applications because of their newly collective properties. However, there is still a lack of a facile and general synthesis strategy to organize and integrate distinct components into complex mesocrystals, and of reported application for them in industrial catalytic reactions. Herein we report a general bottom-up synthesis of CuO-based trimetallic oxide mesocrystals (denoted as CuO-M1Ox-M2Oy, where M1 and M2 = Zn, In, Fe, Ni, Mn, and Co) using a simple precipitation method followed by a hydrothermal treatment and a topotactic transformation via calcination. When these mesocrystals were used as the catalyst to produce trichlorosilane (TCS) via Si hydrochlorination reaction, they exhibited excellent catalytic performance with much increased Si conversion and TCS selectivity. In particular, the TCS yield was increased 19-fold than that of the catalyst-free process. The latter is the current industrial process. The efficiently catalytic property of these mesocrystals is attributed to the formation of well-defined nanoscale heterointerfaces that can effectively facilitate the charge transfer, and the generation of the compressive and tensile strain on CuO near the interfaces among different metal oxides. The synthetic approach developed here could be applicable to fabricate versatile complicated metal oxide mesocrystals as novel catalysts for various industrial chemical reactions.

Synthesis and Characterization of Sn-W Complexes and Crystal Structure of Ph3SnW（CO）3C5H4CH3

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PdPtBi networked nanowires derived from Pd nanosheets as efficient catalysts for ethanol oxidation

Direct ethanol fuel cells(DEFCs)have received increasing attention as one of the most promising energy conversion devices.However,developing catalysts with high activity,long durability and strong anti-poisoning ability for ethanol oxidation is still challenging.Here,using Pd nanosheets as sacrificial templates,we have successfully synthesized PdPtBi networked nanowires(NWs)to improve the activity and stability for ethanol oxidation reaction(EOR)due to the addition of Bi.Density functional theory(DFT)calculations demonstrated the downshift of d-band center of Pd,which is beneficial to suppress CO poisoning and boost reaction kinetics for EOR.Impressively,the PdPtBi networked NWs exhibited the highest activity(11.08 A·mg_(Pd+Pt)^(-1)and 92.52 mA·cm^(-2))with an enhancement of 4.4 and 17.5 times relative to those of Pd/C,respectively and best stability with a 47.2%left versus only a 5.8%left for Pd/C of mass activity after 3,600 s towards EOR.This work deepens the understanding of controllable preparation of networked NWs and provides an effective strategy to design advanced catalysts with high activity and stability.

Size effect of fullerene cages and encaged clusters in M_3N@C_(2n)

Based on the calculated findings that the sizes of encaged clusters determine the structures and the stability of C80-based trimetallic nitride fullerenes (TNFs), more extensive density functional theory calculations were performed on M3N@C68, M3N@C78 and M3N@C80 (M=Sc, Y and La). The calculated results demonstrated that the structures and stability undergo a transition with the increasing of the sizes of the cages and clusters. Sc3N is planar inside the three considered cages, Y3N is slightly pyramidal inside C68-6140 and C78-5 and planar inside I h C80-7, however, La3N is pyramidal inside all the three cages. Those cages with pyramidal clusters inside deformed considerably, compared with their parent cages. In these cases, the bonding of metallic atoms toward the cages does not play an impor-tant role, and the encaged cluster tends to be located inside the cages with the largest M-M and M-C distances so that the strain energy can be released mostly. These calculations revealed the size effect of fullerene cages and encaged clusters, and can explain the position priority of M3N inside fullerene cages and the differences in yield of M3N@C2n.