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

Characterisation of synthesised trimetallic nanoparticles and its influence on anaerobic digestion of palm oil mill effluent

The augmentation of biogas production can be achieved by incorporating metallic nanoparticles as additives within anaerobic digestion. The objective of this current study is to examine the synthesis of Fe-Ni-Zn and Fe-Co-Zn trimetallic nanoparticles using the co-precipitation technique and assess its impact on anaerobic digestion using palm oil mill effluent (POME) as carbon source. The structural morphology and size of the synthesised trimetallic nanoparticles were analysed using a range of characterization techniques, such as X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), and Energy-dispersive X-ray spectroscopy (EDX) . The average size of Fe-Ni-Zn and Fe-Co-Zn were 19-25.5 nm and 19.1-30.5 nm respectively. Further, investigation focused on examining the diverse concentrations of trimetallic nanoparticles, ranging from 0 to 50 mgL-1. The biogas production increased by 55.55% and 60.11% with Fe-Ni-Zn and Fe-Co-Zn trimetallic nanoparticles at 40 mgL-1 and 20 mgL-1, respectively. Moreover, the lowest biogas of 11.11% and 38.11% were found with 10 mgL-1 of Fe-Ni-Zn and Fe-Co-Zn trimetallic nanoparticles. The findings of this study indicated that the trimetallic nanoparticles exhibited interactions with anaerobes, thereby enhancing the degradation process of palm oil mill effluent (POME) and biogas production. The study underscores the potential efficacy of trimetallic nanoparticles as a viable supplement for the promotion of sustainable biogas generation.

PEDOT-embellished Ti3C2Tx nanosheet supported Pt-Pd bimetallic nanoparticles as efficient and stable methanol oxidation electrocatalysts

Exploiting high-efficiency and durable electrocatalysts toward the methanol oxidation reaction (MOR) is crucial for the advancement of direct methanol fuel cells (DMFCs). Herein, we demonstrate the loading of platinum-palladium bimetallic nanoparticles (Pt-Pd NPs) onto poly(3,4-ethylenedioxythiophene) (PEDOT)-embellished titanium carbide (Ti3C2Tx) nanosheets as the electrocatalyst (Ti3C2Tx/PEDOT/Pt-Pd) via a facile and rapid chemical reduction-assisted one-pot hydrothermal process. The structural and morphological analyses of Ti3C2Tx/PEDOT/Pt-Pd indicate that the three-dimensional (3D) hybrid structure formed between PEDOT and Ti3C2Tx provides a sizable active surface and more active sites, which enhances the homogeneous dispersion of the Pt-Pd NPs and facilitates mass transfer. The Schottky junctions formed between PEDOT and Pt-Pd NPs contribute to charge transfer. The electronic effects and synergistic interactions between the support and catalyst favor the electrocatalytic activity of the catalyst. The electrochemical test results reveal that the Ti3C2Tx/PEDOT/Pt-Pd catalyst has prominent electrocatalytic capability for the MOR. Compared with Ti3C2Tx/Pt-Pd and commercial Pt/C catalysts, the Ti3C2Tx/PEDOT/Pt-Pd catalyst has a larger electrochemical activity surface area (ECSA = 122 m2 g-1) and higher mass activity (MA = 1445.4 mA mg-1), as well as better CO tolerance and more reliable long-term durability (a peak current density retention of 71% after 5200 s).

Immobilizing ultrasmall Pt nanocrystals on 3D interweaving BCN nanosheet-graphene networks enables efficient methanol oxidation reaction

Currently, the state-of-the-art anode catalysts employed in direct methanol fuel cells (DMFCs) consist of nanosize Pt dispersed on a carbonaceous support; however, the relatively weak Pt-carbon interfacial interactions severely affect their overall electrocatalytic activity and service life. Herein, we demonstrate a convenient and robust stereo-assembly strategy for the efficient immobilization of ultrasmall Pt nanocrystals on 3D interweaving porous B-doped g-C3N4 nanosheet-graphene networks (Pt/BCN-G) by combining thermal annealing and solvothermal processes. This delicate configuration endowed the resulting hybrid nanoarchitecture with unusual textural merits, including 3D crosslinked porous skeletons, well-separated ultrathin nanosheets, rich B and N species, homogeneous Pt dispersion, stable heterointerface, and high electrical conductivity. Consequently, the 3D Pt/BCN-G nanoarchitecture with an optimized composition exhibited a large electrochemically active surface area of up to 121.2 m2 g-1, high mass activity of 1782.2 mA mg-1, superior poison tolerance, and excellent cycling stability towards the electrooxidation of methanol, all of which exceeded that of the reference Pt/graphene, Pt/BCN, Pt/carbon nanotube, Pt/carbon black, and Pt/g-C3N4 catalysts.

Electrochemically Grown Ultrathin Platinum Nanosheet Electrodes with Ultralow Loadings for Energy-Saving and Industrial-Level Hydrogen Evolution

Nanostructured catalyst-integrated electrodes with remarkably reduced catalyst loadings, high catalyst utilization and facile fabrication are urgently needed to enable cost-effective, green hydrogen production via proton exchange membrane electrolyzer cells (PEMECs). Herein, benefitting from a thin seeding layer, bottom-up grown ultrathin Pt nanosheets (Pt-NSs) were first deposited on thin Ti substrates for PEMECs via a fast, template- and surfactant-free electrochemical growth process at room temperature, showing highly uniform Pt surface coverage with ultralow loadings and vertically well-aligned nanosheet morphologies. Combined with an anode-only Nafion 117 catalyst-coated membrane (CCM), the Pt-NS electrode with an ultralow loading of 0.015 mgPt cm-2 demonstrates superior cell performance to the commercial CCM (3.0 mgPt cm-2), achieving 99.5% catalyst savings and more than 237-fold higher catalyst utilization. The remarkable performance with high catalyst utilization is mainly due to the vertically well-aligned ultrathin nanosheets with good surface coverage exposing abundant active sites for the electrochemical reaction. Overall, this study not only paves a new way for optimizing the catalyst uniformity and surface coverage with ultralow loadings but also provides new insights into nanostructured electrode design and facile fabrication for highly efficient and low-cost PEMECs and other energy storage/conversion devices.

Bio-Fabrication of Trimetallic Nanoparticles and Their Applications

Nanoparticles are materials whose size is less than 100 nm. Because of their distinctive physical and chemical characteristics, nanoparticles have drawn considerable interest in a variety of fields. Biosynthesis of nanoparticles is a green and environmentally friendly technology, which requires fewer chemical reagents, precursors, and catalysts. There are various types of nanomaterials, out of which trimetallic nanoparticles are receiving considerable interest in recent years. Trimetallic nanoparticles possess unique catalytic, biomedical, antimicrobial, active food packaging, and sensing applications as compared to monometallic or bimetallic nanoparticles. Trimetallic nanoparticles are currently synthesized by various methods such as chemical reduction, microwave-assisted, thermal, precipitation, and so on. However, most of these chemical and physical methods are expensive and toxic to the environment. Biological synthesis is one of the promising methods, which includes the use of bacteria, plants, fungi, algae, waste biomass, etc., as reducing agents. Secondary metabolites present in the biological agents act as capping and reducing agents. Green trimetallic nanoparticles can be used for different applications such as anticancer, antibacterial, antifungal, catalytic activity, etc. This review provides an overview of the synthesis of trimetallic nanoparticles using biological agents, and their applications in different areas such as anticancer, antimicrobial activity, drug delivery, catalytic activity, etc. Finally, current challenges, future prospects, and conclusions are highlighted.

Density functional theory based computational investigations on the stability of highly active trimetallic PtPdCu nanoalloys for electrochemical oxygen reduction

Activity, cost, and durability are the trinity of catalysis research for the electrochemical oxygen reduction reaction (ORR). While studies towards increasing activity and reducing cost of ORR catalysts have been carried out extensively, much effort is needed in durability investigation of highly active ORR catalysts. In this work, we examined the stability of a trimetallic PtPdCu catalyst that has demonstrated high activity and incredible durability during ORR using density functional theory (DFT) based computations. Specifically, we studied the processes of dissolution/deposition and diffusion between the surface and inner layer of Cu species of Pt₂₀Pd₂₀Cu₆₀ catalysts at electrode potentials up to 1.2 V to understand their role towards stabilizing Pt₂₀Pd₂₀Cu₆₀ catalysts. The results show there is a dynamic Cu surface composition range that is dictated by the interplay of the four processes, dissolution, deposition, diffusion from the surface to inner layer, and diffusion from the inner layer to the surface of Cu species, in the stability and observed oscillation of lattice constants of Cu-rich PtPdCu nanoalloys.

Demystifying the Chemical Ordering of Multimetallic Nanoparticles

ConspectusMultimetallic nanoparticles (NPs) have highly tunable properties due to the synergy between the different metals and the wide variety of NP structural parameters such as size, shape, composition, and chemical ordering. The major problem with studying multimetallic NPs is that as the number of different metals increases, the number of possible chemical orderings (placements of different metals) for a NP of fixed size explodes. Thus, it becomes infeasible to explore NP energetic differences with highly accurate computational methods, such as density functional theory (DFT), which has a high computational cost and is typically applied to up to a couple of hundred metal atoms. Here, we demonstrate a methodology advancing NP simulations by effectively exploring the vast materials space of multimetallic NPs and accurately identifying the ones with the most thermodynamically preferred chemical orderings. With accuracies reaching that of DFT, our methodology is applicable to practically any NP size, shape, and metal composition. We achieve this by significantly advancing the bond-centric (BC) model, a physics-based model that has been previously shown to rapidly predict bimetallic NP cohesive energies (CEs). Specifically, the BC model is trained in a way to understand how the bimetallic bond strength changes under different coordination environments present on a NP and how the metal composition of every site affects the detailed coordination environment using fractional coordination numbers. This newly modified BC model leads to an improvement from 0.331 (original model) to 0.089 eV/atom in CE predictions when compared to DFT values on a robust data set of 90 different NPs consisting of PtPd, AuPt, and AuPd NPs with varying compositions and chemical orderings. By incorporating the modified BC model into an in-house-developed genetic algorithm (GA) we can effectively and accurately predict the most stable chemical orderings of large, realistic bimetallic NPs consisting of thousands of metal atoms. This is demonstrated on AuPd bimetallic NPs, a challenging system due to the similarity in the cohesion of the two metals. By training our BC model using a unique DFT calculation on a bimetallic NP (one calculation for two metals combining together), we expand to explore the chemical ordering of multimetallic NPs. We first demonstrate the application of our methodology on a AuPdPt NP and validate our stability predictions with literature data. Then, we effectively explore the vast materials space of multimetallic NPs consisting of combinations of Au, Pt, and Pd as a function of metal composition. Our thermodynamic stability trends are presented in a ternary diagram revealing detailed, and yet, unexpected chemical ordering trends. Our computational framework can aid both experimental and computational researchers toward effectively screening multimetallic NP stability. Moreover, we provide an outlook of how this framework can be applied to catalyst discovery, high-entropy alloys, and single-atom alloys.

Sputtering onto liquids: a critical review

Sputter deposition of atoms onto liquid substrates aims at producing colloidal dispersions of small monodisperse ultrapure nanoparticles (NPs). Since sputtering onto liquids combines the advantages of the physical vapor deposition technique and classical colloidal synthesis, the review contains chapters explaining the basics of (magnetron) sputter deposition and the formation of NPs in solution. This review article covers more than 132 papers published on this topic from 1996 to September 2021 and aims at providing a critical analysis of most of the reported data; we will address the influence of the sputtering parameters (sputter power, current, voltage, sputter time, working gas pressure, and the type of sputtering plasma) and host liquid properties (composition, temperature, viscosity, and surface tension) on the NP formation as well as a detailed overview of the properties and applications of the produced NPs.

Synthesis and potential applications of trimetallic nanostructures

The present review highlights the synthetic strategies and potential applications of TMNs for organic reactions, environmental remediation, and health-related activities.

Control of nanoparticles synthesized via vacuum sputter deposition onto liquids: a review

Sputter deposition onto a low volatile liquid matrix is a recently developed green synthesis method for metal/metal oxide nanoparticles (NPs). In this review, we introduce the synthesis method and highlight its unique features emerging from the combination of the sputter deposition and the ability of the liquid matrix to regulate particle growth. Then, manipulating the synthesis parameters to control the particle size, composition, morphology, and crystal structure of NPs is presented. Subsequently, we evaluate the key experimental factors governing the particle characteristics and the formation of monometallic and alloy NPs to provide overall directions and insights into the preparation of NPs with desired properties. Following that, the current understanding of the growth and formation mechanism of sputtered particles in liquid media, in particular, ionic liquids and liquid polymers, during and after sputtering is emphasized. Finally, we discuss the challenges that remain and share our perspectives on the future prospects of the synthesis method and the obtained NPs.

In situ electrochemical activation as a generic strategy for promoting the electrocatalytic hydrogen evolution reaction and alcohol electro-oxidation in alkaline medium

In situ electrochemical activation as a new pre-treatment method is extremely effective for enhanced electrocatalytic performances for different applications. With the help of this method, in situ surface modification of electrocatalyst is achieved without using pre-made seeds or complex synthesis procedure. Herein, with the purpose of finding an in situ and simple electrochemical activation protocol, the green synthesis of Au/Pd nanoparticles (AuPd) by means of polyoxometalate (POM) is reported. Structural analysis of the AuPd nanohybrid unveil the Au-core/Pd-shell structure which surrounded by POM. We propose a novel cathodic electrochemical activation in phosphate buffer solution which can greatly boost the electrocatalytic activity of the as-prepared AuPd and Pd electrocatalyst not only for hydrogen evolution reaction (HER) as a model of electro-reduction, but also for methanol and ethanol electro-oxidation reaction (MOR & EOR). For the HER in 1 M NaOH solution, after the electrochemical activation, the needed potential to drive a geometrical current density of 10 mA cm-2 significantly decreases from - 400 mV vs. the reversible hydrogen electrode (RHE) to -290 mV vs. RHE. For the EOR and MOR, electrochemically activated AuPd realized 3.4- and 2.9- fold increase in mass current density (mA mgPd -1) with respect to the pristine AuPd electrocatalyst, respectively.

Facile One-Pot Biogenic Synthesis of Cu-Co-Ni Trimetallic Nanoparticles for Enhanced Photocatalytic Dye Degradation

Biomolecules from plant extracts have gained significant interest in the synthesis of nanoparticles owing to their sustainable properties, cost efficiency, and environmental wellbeing. An eco-friendly and facile method has been developed to prepare Cu-Co-Ni trimetallic nanoparticles with simultaneous bio-reduction of Cu-Co-Ni metal precursors by aqueous extract of oregano (Origanum vulgare) leaves. Dramatic changes in physicochemical properties of trimetallic nanoparticles occur due to synergistic interactions between individual metal precursors, which in turn outclass the properties of corresponding monometallic nanoparticles in various aspects. The as biosynthesized Cu-Co-Ni trimetallic nanoparticles were initially analyzed using ultraviolet (UV)–visible spectroscopy. The morphology, structure, shape, and size of biosynthesized trimetallic nanoparticles were confirmed by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray diffraction (XRD) spectroscopy. The elemental analysis was carried out by energy-dispersive X-ray (EDX) spectroscopy. Fourier transform infrared (FTIR) microscopy was carried out to explain the critical role of the biomolecules in the Origanum vulgare leaf extract as capping and stabilizing agents in the nanoparticle formation. Additionally, simultaneous thermogravimetric analysis (TGA) and differential thermogravimetry (DTG) analysis was also performed to estimate the mass evaluation and rate of the material weight changes. The photocatalytic activity of as biosynthesized trimetallic nanoparticles was investigated towards methylene blue (MB) dye degradation and was found to be an efficient photocatalyst for dye degradation. Kinetic experiments have shown that photocatalytic degradation of MB dye followed pseudo-first-order kinetics. The mechanism of the photodegradation process of biogenic Cu-Co-Ni trimetallic nanoparticles was also addressed.

Trimetallic Nanoparticles: Greener Synthesis and Their Applications

Nanoparticles (NPs) and multifunctional nano-sized materials have significant applications in diverse fields, namely catalysis, sensors, optics, solar energy conversion, cancer therapy/diagnosis, and bioimaging. Trimetallic NPs have found unique catalytic, active food packaging, biomedical, antimicrobial, and sensing applications; they preserve an ever-superior level of catalytic activities and selectivity compared to monometallic and bimetallic nanomaterials. Due to these important applications, a variety of preparation routes, including hydrothermal, microemulsion, selective catalytic reduction, co-precipitation, and microwave-assisted methodologies have been reported for the syntheses of these nanomaterials. As the fabrication of nanomaterials using physicochemical methods often have hazardous and toxic impacts on the environment, there is a vital need to design innovative and well-organized eco-friendly, sustainable, and greener synthetic protocols for their assembly, by applying safer, renewable, and inexpensive materials. In this review, noteworthy recent advancements relating to the applications of trimetallic NPs and nanocomposites comprising these NPs are underscored as well as their eco-friendly and sustainable synthetic preparative options.

Synthesis, Properties, and Biological Applications of Metallic Alloy Nanoparticles

Metallic alloy nanoparticles are synthesized by combining two or more different metals. Bimetallic or trimetallic nanoparticles are considered more effective than monometallic nanoparticles because of their synergistic characteristics. In this review, we outline the structure, synthesis method, properties, and biological applications of metallic alloy nanoparticles based on their plasmonic, catalytic, and magnetic characteristics.

Facile Histamine Detection by Surface-Enhanced Raman Scattering using SiO2@Au@Ag Alloy Nanoparticles

Histamine intoxication associated with seafood consumption represents a global health problem. The consumption of high concentrations of histamine can cause illnesses ranging from light symptoms, such as a prickling sensation, to death. In this study, gold-silver alloy-embedded silica (SiO2@Au@Ag) nanoparticles were created to detect histamine using surface-enhanced Raman scattering (SERS). The optimal histamine SERS signal was measured following incubation with 125 μg/mL of SiO2@Au@Ag for 2 h, with a material-to-histamine solution volume ratio of 1:5 and a phosphate-buffered saline-Tween 20 (PBS-T) solvent at pH 7. The SERS intensity of the histamine increased proportionally with the increase in histamine concentration in the range 0.1-0.8 mM, with a limit of detection of 3.698 ppm. Our findings demonstrate the applicability of SERS using nanomaterials for histamine detection. In addition, this study demonstrates that nanoalloys could have a broad application in the future.

Advances in Sn-Based Catalysts for Electrochemical CO2 Reduction

The increasing concentration of CO₂ in the atmosphere has led to the greenhouse effect, which greatly affects the climate and the ecological balance of nature. Therefore, converting CO₂ into renewable fuels via clean and economical chemical processes has become a great concern for scientists. Electrocatalytic CO₂ conversion is a prospective path toward carbon cycling. Among the different electrocatalysts, Sn-based electrocatalysts have been demonstrated as promising catalysts for CO₂ electroreduction, producing formate and CO, which are important industrial chemicals. In this review, various Sn-based electrocatalysts are comprehensively summarized in terms of synthesis, catalytic performance, and reaction mechanisms for CO₂ electroreduction. Finally, we concisely discuss the current challenges and opportunities of Sn-based electrocatalysts.

Facile Synthesis of N-Doped Graphene-Like Carbon Nanoflakes as Efficient and Stable Electrocatalysts for the Oxygen Reduction Reaction

A series of N-doped carbon materials (NCs) were synthesized by using biomass citric acid and dicyandiamide as renewable raw materials via a facile one-step pyrolysis method. The characterization of microstructural features shows that the NCs samples are composed of few-layered graphene-like nanoflakes with controlled in situ N doping, which is attributed to the confined pyrolysis of citric acid within the interlayers of the dicyandiamide-derived g-C₃N₄ with high nitrogen contents. Evidently, the pore volumes of the NCs increased with the increasing content of dicyandiamide in the precursor. Among these samples, the NCs nanoflakes prepared with the citric acid/dicyandiamide mass ratio of 1:6, NC-6, show the highest N content of ~6.2 at%, in which pyridinic and graphitic N groups are predominant. Compared to the commercial Pt/C catalyst, the as-prepared NC-6 exhibits a small negative shift of ~66 mV at the half-wave potential, demonstrating excellent electrocatalytic activity in the oxygen reduction reaction. Moreover, NC-6 also shows better long-term stability and resistance to methanol crossover compared to Pt/C. The efficient and stable performance are attributed to the graphene-like microstructure and high content of pyridinic and graphitic doped nitrogen in the sample, which creates more active sites as well as facilitating charge transfer due to the close four-electron reaction pathway. The superior electrocatalytic activity coupled with the facile synthetic method presents a new pathway to cost-effective electrocatalysts for practical fuel cells or metal-air batteries.