Bimetallic Particles Research Articles

Noble-metal-free dual CuNi single-atom embedded in ultrathin ZnIn2S4 for efficient photocatalytic H2 evolution

Developing noble-metal-free dual-metal single-atom catalysts with rich active accessible sites and excellent catalytic activity is very meaningful and challenging, especially for photocatalytic hydrogen production reaction, which can significantly reduce the cost of photocatalytic technology application while reducing the use of noble metals. Herein, a novel noble-metal-free dual CuNi single-atom modified ZnIn2S4 (CuNiSA-ZIS) photocatalyst with high hydrogen production performance were successfully prepared by a hydrothermal method. The ZnIn2S4 with a spherical nanoflower structure is composed of ultrathin nanosheets, and ACHDDAF-STEM results shows that CuNi bimetallic particles are uniformly distributed on the surface of ZnIn2S4 nanosheets and exhibit atomic level dispersion, forming dual-metal single-atom structure. The optimized 1 wt% CuNiSA-ZIS photocatalyst with the Cu/Ni ratio of 1:1 shows the optimum H2 evolution performance with a rate of up to 7844.7 μmol·g−1·h−1 using triethanolamine as a sacrificial reagent, which is significantly improved compared to pristine ZIS, Cu-ZIS and Ni-ZIS samples under simulated sunlight. Electrochemical and spectroscopic characterization results demonstrated that the improved photocatalytic activity of CuNiSA-ZIS was mainly due to the addition of the dual CuNi single atoms with a synergistic effect served as a co-catalyst for ZnIn2S4 photocatalysts, providing efficient active sites for hydrogen evolution while preventing the fast recombination of photo-generated electrons and holes. This study provides a valuable source of ideas for the design of effective noble-metal-free dual-metal single-atom catalysts.

Antimicrobial activity of biogenic-synthesized novel bimetallic nanospinel LiCu-ferrite particles: Experimental and computational studies

An aqueous carob leaf extract was employed in the current study as a biogenic agent (reducing and capping agents) for the synthesis of novel bimetallic lithium and copper-based nanospinel ferrites (LiCu-F) with antibacterial activity. LiCu-F has a considerable number of surface -OH groups, a BET-specific surface area of 72.5 m2/g, a mean particle size of 59.8 nm, and a crystallinity index of 78.9%, according to the results of the physicochemical characterisation of the ferrite. Within the first 60 min, LiCu-F showed bacteriostatic and bactericidal effects on S. aureus and E. coli based on the time-kill assay. 0.4 mg of LiCu-F demonstrated 67.9% bacteriostatic effects on E. coli while exhibiting 100% inactivation of S. aureus strains, demonstrating that the gram-positive bacteria are more susceptible to LiCu-F. The computational molecular docking analysis demonstrated that LiCu-F has a higher binding affinity for S. aureus (-38.89 kcal/mol) than E. coli (-29.16 kcal/mol), which is consistent with the experimental findings. With an LD50 of 1000 mg per kg of body weight based on a computational prediction tool, LiCu-F is cytotoxic to bacteria and can cause DNA damage and cell death in bacterial strains.

Chitosan bimetallic particles with in-situ ROS driven self-cleaning performance for tetracycline elimination

Adsorption enrichment coupled with oxidative degradation is a promising technique for eliminating tetracycline (TC) from an aqueous environment. However, the high cost associated with this technique limits its applicability. Thus, in this study, we synthesized Cu2O and CuFe2O4 bimetallic-modified chitosan particles (Cu(I)–CuFe2O4@CS) with high adsorption efficiency and self-cleaning performance. The self-cleaning performance was driven by the in-situ generated reactive oxygen species (ROS). Batch experiments and characterization methods indicated that 97.39% of TC was rapidly adsorbed on the particles surface and subsequently degraded by in-situ generated ROS, to achieve a self-cleaning process. The Cu(I)–CuFe2O4@CS/TC system exhibited maximum O2•- and H2O2 concentration of 12.95 μmol/L and 42.05 μmol/L, respectively. Cu2O was the main source of the ROS generation, while CuFe2O4 effectively adsorbed TC and contributed to the synergistic accumulation of ROS. Moreover, the adsorbed TC with reductive functional properties facilitated the reduction of Fe(III)/Fe(II) and Cu(II)/Cu(I) cycles, thereby improving TC elimination efficiency.

Conductive polyacrylate coatings filled with bimetal Cu–Ni, Zn–Cu, or Zn–Ni powders and graphene nanoplatelets

AbstractConductive coatings on a glass substrate are widely used in electronics and automotive, ship, aircraft, and optical industries. The method for obtaining electroconductive polyacrylate coatings filled with bimetal Cu–Ni, Zn–Cu, or Zn–Ni particles and graphene nanoplatelets (GNPs) is developed in this work. At the ratio GNPs:bimetal powder:polymer of (33–35):(17–35):(30–50) (wt%) and the coating thickness 50 μm specific volume resistance is 0.12–0.26 Ω·cm owing to the percolation effect. Bimetal particles are synthesized by nickel or copper ions reduction from aqueous solutions on copper or zinc particles. Their composition is regulated by the duration of metal ions reduction. Bimetal particles have a structure of copper or zinc core with a loose shell of nickel or copper nanoparticles, they ensure the contact between GNPs forming a continuous network in polymer matrix. GNPs are obtained by thermal exfoliation of natural flake graphite treated in liquid ammonia containing metal sodium. Polymer composite is prepared using the solution of methyl‐ and n‐butylmethacrylate copolymer. Coatings have adequate adhesion to the glass, and owing to their high conductivity, absence of noble metals, simplicity and cheapness of fabrication can be used for production of conductive elements on glass and other substrates.Highlights Cu–Ni, Zn–Cu, or Zn–Ni powder and GNPs filled conductive polyacrylate coatings Bimetal core‐shell particles are obtained by Ni(II) or Cu(II) reduction in solutions Bimetal particles and GNPs form a network in polymer with percolation effect Specific volume resistance of coatings 50 μm thick on glass is 0.12–0.26 Ω·cm Coatings conductivity and adhesion to glass open great prospects for application

Exsolution-enhanced reverse water-gas shift chemical looping activity of Sr2FeMo0.6Ni0.4O6-δ double perovskite

This study investigates the structural evolution and redox characteristics of the double perovskite Sr2FeMo0.6Ni0.4O6-δ (SFMN) during hydrogen (H2) and carbon dioxide (CO2) redox cycles and explores the material performance in the Reverse Water-Gas Shift Chemical Looping (RWGS-CL) reaction. In-situ and ex-situ X-Ray Diffraction (XRD) and High-Resolution Transmission Electron Microscopy (HRTEM) studies reveal that H2 reduction at temperatures above 800 °C leads to the exsolution of bimetallic Ni-Fe alloy particles and the formation of a Ruddlesden-Popper (RP) phase. A core–shell structure with Ni-Fe core and a perovskite oxide shell is formed with subsequent redox cycles, and the resulting material exhibits better performance and high stability in the RWGS-CL process. Thermogravimetric (TGA) and Temperature Programmed Reduction (TPR) and Oxidation (TPO) analyses show that the optimal reduction and oxidation temperatures for maximizing the CO yield are around 850 °C and 750 °C respectively, and that the cycled material is able to work steadily under isothermal conditions at 850 °C.

Stabilization and anchoring of palladium‐copper alloy on murexide modified carbon nanotube as a superb nanocatalyst: Excellent performance in coupling and synthetic reactions

Sketching a proper catalytic system with supplementary attributes, containing easy separation, wide surface area, supreme loading capacity, and fantastical electronic attributes, proposes an encouraging direction for efficiently using nanostructures for various applications. However, the capability to adjust the nano‐measure bimetallic particles is an adjustment for attaining superb performance in the catalytic field. Herein, an environmentally benign approach was developed for immobilizing and anchoring Pd‐Cu alloy nanoparticles on murexide (MX)‐functionalized carbon nanotubes (CNTs). Afterward, the catalytic activity of Pd2‐Cu3@MX/CNT was studied in synthesizing 2,3‐dihydro quinazoline‐4(1H)‐ones and carbon–carbon coupling reactions at sustainable reaction conditions under ultrasound irradiation. The results demonstrated that high‐affinity MX ligand and porous CNT structures than the adsorption of Pd–Cu had a unique designation in the high‐range constancy of the alloy nanoparticles and following catalytic activity. In addition, ultrasound irradiation got electrons of Pd–Cu alloy nanoparticles agitated, constructing a synergic efficacy between Cu and Pd metals for synthesis and coupling reactions. Our study represents that the designed catalyst is green, recyclable, and most suitable, providing new intuition into in high‐range constancy of bimetallic nanoparticles for broad applications.

TiO2 supported non-noble Ni-Fe catalysts for the high yield production of 2,5-dimethylfuran biofuel

The establishment of the future biorefinery schemes requires the sustainable conversion and valorisation of renewable bioresources into eco-friendly fuels and chemicals. To this end, 2,5-dimethylfuran (DMF) is a promising biofuel competitive to benchmarks like ethanol due to high-value intrinsic properties. It can be produced by the catalytic hydrogenation of the 5-hydroxymethylfurfural (HMF) platform molecule, one of the biobased intermediate chemicals derived from the abundant lignocellulosic biomass. We evidenced that bimetallic NiFe alloys supported on TiO2 are earth-abundant non-noble metal-based catalysts allowing the high yield production of DMF to be achieved. We showed that the preparation method and the reduction temperature of the catalyst are of prime importance, and are directly influencing the structure of the supported NiFe bimetallic particles and in consequence the catalyst behaviour. The highest yield to DMF is obtained on a catalyst prepared by co-impregnation and reduced at 500 °C, that features an unperfect core/shell structure of the NiFe alloy, with a partial Fe shell surrounding an Fe-enriched Ni core. The key-feature necessary for achieving high performance lies on the surface structure of the NiFe alloy that allows for an optimum availability of highly active Ni domains. The Ni atoms were maintained highly dispersed by the presence of Fe-containing surface phases. The specific surface structure is proposed to promote the HMF adsorption through the carbonyl group, while preventing from the hydrogenation of the aromatic furan ring to maintain high selectivity.

Preparation of Fe/Cu bimetals by ball milling iron powder and copper sulfate for trichloroethylene degradation: Combined effect of FeSx and Fe/Cu alloy

The addition of a secondary metal (such as Cu, Co, Ni and Pd) to form iron-based bimetallic particles could enhance the reactivity of zero valent iron (ZVI). This study proposed a new synthesis method for preparing Cu-Fe bimetals (Cu-Febm (CuSO4)) by ball milling mZVI and CuSO4. During ball-milling process, 40% of Cu2+ can be reduced to Cu0, which formed galvanic couple with Fe0 in a way of Fe/Cu alloy structure. Part Cu2+ was only reduced to Cu+ (corresponding to Cu2O), while 29% of SO42- was reduced to Sx2- (corresponding to FeSx). The appearance of Cu2O was not conducive to the activity of Cu-Febm (CuSO4) particles, the formation of Fe0/FeSx structure compensated for the partial loss of Fe/Cu alloy. H•abs was identified as the main active species for TCE degradation by Cu-Febm (CuSO4) bimetals. The Cu-Febm (CuSO4) bimetals has great potential for the removal of chlorinated hydrocarbons in water.

Biochar as an electron shuttle loaded with Fe/Ni bimetallic nanoparticles for efficient removal of 2,4-dichlorophenols: Performance, degradation pathway and mechanism

Biochar can be served as a substrate for immobilizing bimetallic particles and applied in the pollutant removal, however, its specific role and mediated electron shuttle mechanism against 2,4-dichlorophenol (2,4-DCP) have not been elucidated. In this study, biochar loaded with Fe/Ni bimetallic nanoparticles (BC@Fe/Ni) was optimally synthesized, and its dechlorination performance, pathway and mechanism towards 2,4-DCP were investigated. The results showed that BC@Fe/Ni was more effective compared to Fe/Ni nanoparticles in the 2,4-DCP removal due to its well-dispersed Fe/Ni nanoparticles and increased electron-shuttling capability. The optimal parameters for 2,4-DCP removal by BC@Fe/Ni were assessed, the highest removal efficiency equivalent to 50 mg L−1 of 2,4-DCP was achieved at pH 4.0 with a dosage of 2 g L−1. The 2,4-DCP removal was an adsorption-dechlorination-adsorption pathway, primarily through para-Cl elimination, ortho-Cl elimination and finally phenol adsorption. The removal mechanism of 2,4-DCP by BC@Fe/Ni may involve the 2,4-DCP reductive dechlorination by nZVI, atomic hydrogen and biochar-mediated electron transfer, and final adsorption by biochar. In summary, this study demonstrates that biochar is a promising electron shuttle for immobilizing bimetallic particles and serves as a reference for the dechlorination mechanism of chlorinated organic pollutants by biochar-based bimetallic nanomaterials.

Electron synergy effect in the PtCo/CNTs bimetallic catalysts for promoting highly selective and stable hydrogenation of crotonaldehyde

Herein, we synthesized PtCo/CNTs, Pt/CNTs, and Co/CNTs nanocatalysts at room temperature by chemical reduction method. The synergistic effect in PtCo/CNTs for crotonaldehyde (CAL) hydrogenation is investigated. The nanostructures, morphologies, electronic property, Pt–Co interaction, surface characteristic and composition of the catalysts are examined by XRD, BET, SEM, XPS, HRTEM, STEM, STEM-EDX elemental maps and line profiles and H2-TPD. It is found that Pt and Co forms PtCo bimetallic nanoparticles in the PtCo/CNTs catalyst and the PtCo bimetallic nanoparticles are coated on multi-walled carbon nanotubes. And PtCo/CNTs achieves 83.5% CAL conversion, 91.3% crotyl alcohol (COL) selectivity, and 647.4 h−1 turnover frequency (TOF) at 60 °C within 2 h under 3 MPa hydrogen, and its catalytic performance remains basically unchanged after five recycles. According to the analysis, the presence of PtCo bimetallic particles lead to electron transferring from Co to Pt (synergy effect), which improves their activation ability of hydrogen and desorption of CC in COL and thus enhances its selectivity to COL.

Preparation and Electrocatalytic Activity of Bimetallic Ni-Cu Micro- and Nanoparticles

Bimetallic Ni/Cu core–shell and Cu-Ni heterostructural micro- and nanoparticles were prepared using two simple successive reduction procedures. Monometallic Ni and Cu particles were synthesized for comparison. The phase constitutions and morphological features of the particles were studied by means of X-ray diffraction, energy-dispersive X-ray spectroscopy, and scanning electron microscopy methods. All the prepared mono- and bimetallic particles were applied as electrocatalysts in the electrohydrogenation of p-nitrophenol (p-NPh). An additional electrochemical reduction of copper cations during the hydrogen saturation of Cu-containing particles was established. The prepared Ni/Cu particles exhibited the highest electrocatalytic activity with an increase in the hydrogenation rate of p-NPh by more than three times compared to its electrochemical reduction on the nonactivated cathode, and p-NPh conversion yielded the maximum values. The main product of p-NPh electrocatalytic hydrogenation over Ni-Cu particles is p-aminophenol, which is an intermediate in the synthesis of many drugs. p-Aminophenol formation is confirmed by UV-Vis spectra.

Towards Low Temperature Operation of Catalytic Gas Sensors: Mesoporous Co3O4-Supported Au-Pd Nanoparticles as Functional Material.

It is shown that the operating temperature of pellistors for the detection of methane can be reduced to 300 °C by using Au-Pd nanoparticles on mesoporous cobalt oxide (Au-Pd@meso-Co3O4). The aim is to reduce possible catalyst poisoning that occurs during the high-temperature operation of conventional Pd-based pellistors, which are usually operated at 450 °C or higher. The individual role of Au-Pd as well as Co3O4 in terms of their catalytic activity has been investigated. Above 300 °C, Au-Pd bimetallic particles are mainly responsible for the catalytic combustion of methane. However, below 300 °C, only the Co3O4 has a catalytic effect. In contrast to methane, the sensor response and the temperature increase of the sensor under propane exposure is much larger than for methane due to the larger heat of combustion of propane. Due to its lower activation energy requirement, propane exhibits a higher propensity for oxidation compared to methane. As a result, the detection of propane can be achieved at even lower temperatures due to its enhanced reactivity.

In Situ Formation of Ru–Sn Bimetallic Particles for Non-Oxidative Coupling of Methane

In Situ Formation of Ru–Sn Bimetallic Particles for Non-Oxidative Coupling of Methane

Enriching Pt3 ensemble with isolated 3-fold hollow site by crystal-phase engineering of Pt3Fe single-nanoparticle for acetylene hydrogenation

Tuning the crystal-phase of bimetallic particles enables a precise control of catalytically active sites but is experimentally challenged by the averaging ensemble effects that are caused by the particle communications occurred during the crystal-phase transformation. Here, H2-treatment at 773–973 K of Pt3Fe single-nanoparticle, confined by a permeable silica shell, achieved crystal-phase transformation from the disordered A1 phase to the chemically ordered L12 phase. Detailed microscopic and spectroscopic characterizations have identified that the disordered A1 particle possessed contiguously connected large Pt domains while the ordered L12 particle afforded regularly populated Pt3 ensembles surrounded by Fe single-atoms. The isolated 3-fold hollow Pt site in the three-atom ensemble efficiently boosted the adsorption of acetylene, yielding a much higher hydrogenation activity. The reaction rate of the L12 particle was twice of that for the A1 particle. Moreover, the charge transfer from the neighboring Fe single-atoms to the Pt atoms on the L12 particle expedited the desorption of ethylene, promoting the selectivity as well. Overall, both geometric and electronic interactions in the ordered crystal-phase synergistically facilitated the selective hydrogenation of acetylene to ethylene.

Bimetallic Nanoalloy Catalysts for Green Energy Production: Advances in Synthesis Routes and Characterization Techniques.

Bimetallic Nanoalloy catalysts have diverse uses in clean energy, sensing, catalysis, biomedicine, and energy storage, with some supported and unsupported catalysts. Conventional synthetic methods for producing bimetallic alloy nanoparticles often produce unalloyed and bulky particles that do not exhibit desired characteristics. Alloys, when prepared with advanced nanoscale methods, give higher surface area, activity, and selectivity than individual metals due to changes in their electronic properties and reduced size. This review demonstrates the synthesis methods and principles to produce and characterize highly dispersed, well-alloyed bimetallic nanoalloy particles in relatively simple, effective, and generalized approaches and the overall existence of conventional synthetic methods with modifications to prepare bimetallic alloy catalysts. The basic concepts and mechanistic understanding are represented with purposely selected examples. Herein, the enthralling properties with widespread applications of nanoalloy catalysts in heterogeneous catalysis are also presented, especially for Hydrogen Evolution Reaction (HER), Oxidation Reduction Reaction (ORR), Oxygen Evolution Reaction (OER), and alcohol oxidation with a particular focus on Pt and Pd-based bimetallic nanoalloys and their numerous fields of applications. The high entropy alloy is described as a complicated subject with an emphasis on laser-based green synthesis of nanoparticles and, in conclusion, the forecasts and contemporary challenges for the controlled synthesis of nanoalloys are addressed.

Nano Architectonics of Fe–Cu Bimetallic Particles Confined in a Mesoporous Silica Network for the Synthesis of 5-Substituted 1H-tetrazoles

Nano Architectonics of Fe–Cu Bimetallic Particles Confined in a Mesoporous Silica Network for the Synthesis of 5-Substituted 1H-tetrazoles

Single step synthesis of amine functionalized graphene oxide/Cu-Ni bimetallic nanocomposite and tuning its electrical properties

A facile chemical method was adopted for the synthesis of bimetallic Cu-Ni particles supported on amine-functionalized graphene oxide (AGO). The amine functionalized graphene oxide (AGO) and different nanocomposites were characterized by X-ray photoelectron spectroscopy,which indicated that Cu and Ni nanoparticles were partially oxidized on the surface layer AGO.The optical direct bandgap of AGO and its nanocomposite were in the range of 5.1–5.6 eV. The PL emission spectra of these nanocomposites showed different defects related to PL emission peaks.The interaction between the metal oxide and GO was calculated from the Perdew-Becke-Ernzeroff density functional theory and from the results it is observed thatmetal oxides were adsorbed on the GO surface, and the cation-π interaction was responsible for the most stable orientation. Electrical conductivity and relaxation were significantly pronounced in low/mid-temperature zones. Moreover, AGO-Cu/Ni (1:0) showed the highest conductivity and excellent efficiency and may be used as potential candidate for smart electrical device fabrication.

Mechanochemically Assisted Synthesis of Cu–Ag Microflakes

In this work, a simple, inexpensive, and eco-friendly synthesis method of Cu−Ag microflakes has been developed. Firstly, Cu nanoparticles were synthesized by the reduction of copper nitrate in ethylene glycol at 180 °C in the presence of NaOH. The as-synthesized Cu powder was then dispersed in a mixture of ethyl alcohol and a dispersant followed by the mechanochemical treatment of the dispersion in a ball mill resulting in the formation of Cu flakes of approximately 0.2 μm thick and 2.7 μm lateral size. Next, by adding AgNO3 dissolved in H2O into the Cu particle dispersion, the bimetallic Cu−Ag microflakes were prepared. The particles so prepared were investigated by X-ray phase analysis and electron microscopy. It was shown that the Cu−Ag bimetallic particles were also flake-like in shape and similar in size to the original Cu microflakes. The effect of synthesis conditions, including parameters of mechanochemical processing, on thickness, size, and uniformity of the bimetallic microflakes was studied. The results obtained in this study were compared with those obtained by wet chemical synthesis alone. The flake-like Cu–Ag particles are supposed to be used in the manufacture of conductive pastes, adhesives, and composites for printed electronics.

Fabrication of Metal Ion–BSA Chelation-Targeted Surface-Imprinted Particles for Protein Separation

The development of high-performance protein-imprinted materials for adsorption and separation to obtain high-purity, high-quality biomolecules is still one of the most important techniques to promote the rapid development of the protein drug industry. In this paper, a novel highly specific bovine serum albumin (BSA) cobalt–molybdenum double-hydroxides surface-imprinted composite particles (Co–Mo LDHs@MIPs) were constructed by the surface imprinting technique combined with metal chelation. ZIF-67 was etched by molybdate ions to obtain unique MOF-derived bimetallic hydroxide particles (Co–Mo LDHs), which were used as the carrier. The rough outer surface and bimetallic ion coordination of Co–Mo LDHs enable anchoring more template proteins. The adsorption capacity of Co–Mo LDHs@MIPs was up to 423.37 mg/g for BSA in 60 min with an imprinting factor of 2.65. In addition, Co–Mo LDHs@MIPs can selectively recognize and separate BSA from mixed proteins and fetal bovine serum and exhibit high reusability stability.

Fe-Ni/MWCNTs Nano-Composites for Hexavalent Chromium Reduction in Aqueous Environment.

A novel Cr (VI) removal material was designed and produced comprising multi-walled carbon nanotubes (MWCNTs) as a support with a high specific surface area and the loaded Fe-Ni bimetallic particles as catalytic reducing agents. Such a design permits the composite particle to perform the adsorption, reduction, and immobilisation of Cr (VI) quickly and efficiently. Due to MWCNTs' physical adsorption, Cr (VI) in solution aggregates in the vicinity of the composite, and Fe rapidly reduces Cr (VI) to Cr (III) catalysed by Ni. The results demonstrated that the Fe-Ni/MWCNTs exhibits an adsorption capacity of 207 mg/g at pH = 6.4 for Cr (VI) and 256 mg/g at pH 4.8, which is about twice those reported for other materials under similar conditions. The formed Cr (III) is solidified to the surface by MWCNTs and remains stable for several months without secondary contamination. The reusability of the composites was proven by retaining at least 90% of the adsorption capacity for five instances of reutilization. Considering the facile synthesis process, low cost of raw material, and reusability of the formed Fe-Ni/MWCNTs, this work shows great potential for industrialisation.