Au-Ag alloy nanoparticles with tunable cavity for plasmon-enhanced photocatalytic H2 evolution

Au-Ag alloy nanoparticles with different cavity sizes have great potential for improving photocatalytic performance due to their tunable plasmon effect.In this study,galvanic replacement was combined with co-reduction with the reaction kinetics processes regulated to rapidly synthesize Au-Ag hollow alloy nanoparticles with tunable cavity sizes.The position of the localized surface plasmon resonance(LSPR)peak could be effectively adjusted between 490 nm and 713 nm by decreasing the cavity size of the Au-Ag hollow nanoparticles from 35 nm to 20 nm.The plasmon-enhanced photocatalytic H2 evolution of alloy nanoparticles with different cavity sizes was investigated.Compared with pure P25(TiO2),intact and thin-shelled Au-Ag hollow nanoparticles(HNPs)-supported photocatalyst exhibited an increase in the photocatalytic H2 evolution rate from 0.48μmol h^−1 to 4μmol h^−1 under full-spectrum irradiation.This improved photocatalytic performance was likely due to the plasmon-induced electromagnetic field effect,which caused strong photogenerated charge separation,rather than the generation of hot electrons.

Encapsulated Ni-Co alloy nanoparticles as efficient catalyst for hydrodeoxygenation of biomass derivatives in water

Catalytic hydrodeoxygenation(HDO)is one of the most promising strategies to transform oxygen-rich biomass derivatives into high value-added chemicals and fuels,but highly challenging due to the lack of highly efficient nonprecious metal catalysts.Herein,we report for the first time of a facile synthetic approach to controllably fabricate well-defined Ni-Co alloy NPs confined on the tip of N-CNTs as HDO catalyst.The resultant Ni-Co alloy catalyst possesses outstanding HDO performance towards biomass-derived vanillin into 2-methoxy-4-methylphenol in water with 100%conversion efficiency and selectivity under mild reaction conditions,surpassing the reported high performance nonprecious HDO catalysts.Impressively,our experimental results also unveil that the Ni-Co alloy catalyst can be generically applied to catalyze HDO of vanillin derivatives and other aromatic aldehydes in water with 100%conversion efficiency and over 90%selectivity.Importantly,our DFT calculations and experimental results confirm that the achieved outstanding HDO catalytic performance is due to the greatly promoted selective adsorption and activation of C=O,and desorption of the activated hydrogen species by the synergism of the alloyed Ni-Co NPs.The findings of this work affords a new strategy to design and develop efficient transition metal-based catalysts for HDO reactions in water.

Low temperature synthesis and thermal properties of Ag-Cu alloy nanoparticles

Ag-Cu alloy nanoparticles were synthesized by simple low temperature chemical reduction method using metal salts（acetate/sulphates） in aqueous solution with sodium borohydride as reducing agent.The chemical reduction was carried out in the presence of nitrogen gas in order to prevent the oxidation of copper during the reaction process.The alloy nanoparticles were characterized by XRD,UV-Vis,particle size analysis,EDS,TG-DTA and SEM analysis.From the XRD analysis,the crystallite sizes of the prepared samples were calculated using Scherrer formula and the values were found to be in the range of 15 nm.UV-Vis studies conform the formation of alloy nanoparticles.EDS analysis shows the presence of silver and copper in the samples.The SEM observation reveals that the samples consist of grains with average grain size up to 40 nm,and the particle size dependant melting point was studied by TG-DTA.

Sustainable solid-state synthesis of uniformly distributed PdAg alloy nanoparticles for electrocatalytic hydrogen oxidation and evolution

New sustainable syntheses based on solid-state strategies have sparked enormous attention and provided novel routes for the synthesis of supported metallic alloy nanocatalysts(SMACs).Despite considerable recent progress in this field,most of the developed methods suffer from either complex operations or poorly controlled morphology,which seriously limits their practical applications.Here,we have developed a sustainable strategy for the synthesis of PdAg alloy nanoparticles(NPs)with an ultrafine size and good dispersion on various carbon matrices by directly grinding the precursors in an agate mortar at room temperature.Interestingly,no solvents or organic reagents are used in the synthesis procedure.This simple and green synthesis procedure provides alloy NPs with clean surfaces and thus an abundance of accessible active sites.Based on the combination of this property and the synergistic and alloy effects between Pd and Ag atoms,which endow the NPs with high intrinsic activity,the PdAg/C samples exhibit excellent activities as electrocatalysts for both the hydrogen oxidation and evolution reactions(HOR and HER)in a basic medium.Pd9Ag1/C showed the highest activity in the HOR with the largest j0,m value of 26.5 A g Pd^–1 and j0,s value of 0.033 mA cmPd^–2,as well as in the HER,with the lowest overpotential of 68 mV at 10 mA cm^–2.As this synthetic method can be easily adapted to other systems,the present scalable solid-state strategy may open opportunity for the general synthesis of a wide range of well-defined SMACs for diverse applications.

Facile fabrication of ultrafine nickel-iridium alloy nanoparticles/graphene hybrid with enhanced mass activity and stability for overall water splitting

Developing active and durable electrocatalysts for overall water splitting is desirable but challenging to realize sustainable hydrogen production.Here,we report a facile and general method to prepare ultrafine nickel(Ni)-iridium(Ir)alloy nanoparticles/graphene hybrids for overall water splitting.The optimized hybrid with 4.9 wt%Ir exhibits much higher catalytic activity and durability than commercial 20 wt%Ir/C for both oxygen evolution reaction(OER)and hydrogen evolution reaction(HER).Theoretical simulations reveal that the incorporation of Ir in metallic Ni lattice regulates hydrogen adsorption free energy to the optimum level,thus improving HER activity,while in situ generated amorphous Ir-Ni hydr(oxy)oxides around metallic Ni-Ir core have been demonstrated to be the active species under OER conditions,which switches OER rate-determining step to energy-favorable pathway.The overall water splitting electrolyzer assembled by the optimized electrocatalyst shows a low cell voltage of only 1.52 V and excellent stability to deliver a current density of 10 m A cm-2.This work provides a powerful strategy toward general synthesis of ultrafine alloy nanoparticles for high-performance overall water splitting.

Structural optimization and segregation behavior of quaternary alloy nanoparticles based on simulated annealing algorithm

Alloy nanoparticles exhibit higher catalytic activity than monometallic nanoparticles, and their stable structures are of importance to their applications. We employ the simulated annealing algorithm to systematically explore the stable structure and segregation behavior of tetrahexahedral Pt–Pd–Cu–Au quaternary alloy nanoparticles. Three alloy nanoparticles consisting of 443 atoms, 1417 atoms, and 3285 atoms are considered and compared. The preferred positions of atoms in the nanoparticles are analyzed. The simulation results reveal that Cu and Au atoms tend to occupy the surface, Pt atoms preferentially occupy the middle layers, and Pd atoms tend to segregate to the inner layers. Furthermore, Au atoms present stronger surface segregation than Cu ones. This study provides a fundamental understanding on the structural features and segregation phenomena of multi-metallic nanoparticles.

Unraveling the role of iron on Ni-Fe alloy nanoparticles during the electrocatalytic ethanol-to-acetate process

The anodic electrooxidation of ethanol to value-added acetate is an excellent example of replacing the oxygen evolution reaction to promote the cathodic hydrogen evolution reaction and save energy.Herein,we present a colloidal strategy to produce Ni-Fe bimetallic alloy nanoparticles(NPs)as efficient electrocatalysts for the electrooxidation of ethanol in alkaline media.Ni-Fe alloy NPs deliver a current density of 100 mA·cm^(-2) in a 1.0 M KOH solution containing 1.0 M ethanol merely at 1.5 V vs.reversible hydrogen electrode(RHE),well above the performance of other electrocatalysts in a similar system.Within continuous 10 h testing at this external potential,this electrode is able to produce an average of 0.49 mmol·cm^(-2)·h^(-1) of acetate with an ethanol-to-acetate Faradaic efficiency of 80%.A series of spectroscopy techniques are used to probe the electrocatalytic process and analyze the electrolyte.Additionally,density functional theory(DFT)calculations demonstrate that the iron in the alloy NPs significantly enhances the electroconductivity and electron transfer,shifts the rate-limiting step,and lowers the energy barrier during the ethanol-to-acetate reaction pathway.

Plasma-enabled synthesis of ordered PtFe alloy nanoparticles encapsulated with ultrathin N-doped carbon shells for efficient methanol electrooxidation

Methanol oxidation reaction(MOR),the key reaction for clean energy generation in fuel cells,is kinetically sluggish and short-lasting because of insufficient catalytic activity and stability of the common Pt-based electrocatalysts.Ordered Pt alloy structures which promise to surmount these issues,are challenging and impractical to fabricate using common high-temperature annealing.To address the urgent need for simple and rapid synthesis methods for such alloys,here we report the versatile plasma-assisted thermal annealing synthesis of a robust electrocatalyst with PtFe alloys supported on N-doped carbon nanotubes(denoted as PtFe@NCNT-P).Benefiting from the reactive plasma-specific effects,the PtFe@NCNT-P electrocatalyst features ultrafine PtFe alloy nanoparticles(mean size~2.88 nm,ordered degree~87.07%)and ultrathin N-doped carbon(NC)shells(0.3–0.7 nm),leading to the excellent catalytic activity and stability toward MOR.The catalyst shows the specific and mass activities of 3.99 mA/cm^(2)and 2,148.5 mA/mg,which are 7.82 and 7.41 times higher than those for commercial Pt/C(0.51 mA/cm^(2),290 mA/mg),and 2.18 and 2.59 times higher compared to the plasma-untreated PtFe@NCNT(1.83 mA/cm2,829.5 mA/mg),respectively.The PtFe@NCNT-P further exhibits extraordinary stability during the long-term chronoamperometry test and 1,000-cycle cyclic voltammetry scanning,much better compared to PtFe@NCNT samples even after the longer thermal annealing.These findings show great potential of the plasma-enabled synthesis of high-performance carbon-supported metallic electrocatalysts for the emerging clean energy technologies.

Formic acid dehydrogenation reaction on high-performance Pd_(x)Au_(1−x) alloy nanoparticles prepared by the eco-friendly slow synthesis methodology

Dehydrogenation of formic acid (FA) is considered to be an effective solution for efficient storage and transport of hydrogen. For decades, highly effective catalysts for this purpose have been widely investigated, but numerous challenges remain. Herein, the Pd_(x)Au_(1−x) (x = 0, 0.2, 0.4, 0.5, 0.6, 0.8, 1) alloys over the whole composition range were successfully prepared and used to catalyze FA hydrogen production efficiently near room temperature. Small PdAu nanoparticles (5–10 nm) were well-dispersed and supported on the activated carbon to form PdAu solid solution alloys via the eco-friendly slow synthesis methodology. The physicochemical properties of the PdAu alloys were comprehensively studied by utilizing various measurement methods, such as X-ray diffraction (XRD), N2 adsorption–desorption, high angle annular dark field-scanning transmission electron microscope (HAADF-STEM), X-ray photoelectrons spectroscopy (XPS). Notably, owing to the strong metal-support interaction (SMSI) and electron transfer between active metal Au and Pd, the Pd0.5Au0.5 obtained exhibits a turnover frequency (TOF) value of up to 1648 h−1 (313 K, nPd+Au/nFA = 0.01, nHCOOH/nHCOONa = 1:3) with a high activity, selectivity, and reusability in the FA dehydrogenation.

Enhanced catalytic activity of monodispersed AgPd alloy nanoparticles assembled on mesoporous graphitic carbon nitride for the hydrolytic dehydrogenation of ammonia borane under sunlight

We address the composition-controlled synthesis of monodispersed AgPd alloy nanoparticles （NPs）, their assembly for the first time on mesoporous graphitic carbon nitride （mpg-C3N4）, and the unprecedented catalysis of mpg-CgN4@AgPd in the hydrolytic dehydrogenation of ammonia borane （AB） at room temperature. Monodispersed AgPd alloy NPs were synthesized using a high-temperature organic-phase surfactant-assisted protocol comprising the co-reduction of silver（I） acetate and palladium（II） acetylacetonate in the presence of oleylamine, oleic acid, and 1-0ctadecene. This protocol allowed the synthesis of four different compositions of AgPd alloy NPs. The AgPd alloy NPs were then assembled on mpg-C3N4, reduced graphene oxide, and Ketjenblack using a liquid-phase self-assembly method. Among the three supports tested, the mpg-CBN4@AgPd catalysts provided the best activity because of the Mott-Schottky effect, which was driven by the favorable work function difference between mpg-CBN4 and the metal NPs. Moreover, the activity of the mpg-CBN4@AgPd catalyst was further enhanced by an acetic acid treatment （AAt）, and a record initial turnover frequency of 94.1 mOl（hydrogen）＇mOl（catalyst）-l-min-1 was obtained. Furthermore, the mpg-CBN4@Ag42Pdss-AAt catalyst also showed moderate durability for the hydrolysis of AB. This study also includes a wealth of kinetic data for the mpg-CBN4@AgPd-catalyzed hydrolysis of AB.

Platinum-copper alloy nanoparticles armored with chloride ion transporter to promote electro-driven tumor inhibition

The induction of oxidative species,driven by oscillating electric field(E),has recently emerged as an effective approach for tumor inhibition,so-called electrodynamic therapy(EDT).While it offers a series of advantages attracting considerable attention,the fundamental mechanism and improvement strategies for EDT approach are being endeavored extensively with the aid of new material explorations.An interesting phenomenon observed in early studies is that the on-site concentration of chloride ion is highly favored for the induction of oxidative species and the efficacy of tumor inhibition.Following this discovery ignored previously,here for the first time,fine Pt/Cu alloy nanoparticles(PtCu_(3) NPs)are integrated with chloride ion transporter(CIT)for EDT-based combinational therapy.In this system,while PtCu_(3) NPs induce oxidative species under an electric field,it also effectively transforms endogenous H_(2)O_(2) into·OH and consumes intracellular glutathione(GSH).More importantly,with the aid of CIT,PtCu_(3)-PEG@CIT NPs promote the intracellular concentration of chloride ion(Cl^(-))by transporting extracellular Cl^(-),facilitating the generation of oxidative species considerably.Meanwhile,CIT delivered intracellularly increases lysosomal pH,leading to the disruption of cellular autophagy and weakening the treatment resistance.In consequence,significant tumor inhibition is enabled both in vitro and in vivo,due to the combination of unique characteristics offered by PtCu_(3)-PEG@CIT.

Stabilization of Cu/Ni Alloy Nanoparticles with Graphdiyne Enabling Efficient CO_(2) Reduction

Electrocatalysis has become an attractive strategy for the artificial reduction of CO_(2) to high-value chemicals.However,the design and development of highly selective and stable non-noble metal electrocatalysts that convert CO_(2) to CO are still a challenge.As a new type of two-dimensional carbon material,graphdiyne(GDY),is rarely used to explore the application in carbon dioxide reduction reaction(CO_(2)RR).Therefore,we tried to use GDY as a substrate to stabilize the copper-nickel alloy nanoparticles(NPs)to synthesize Cu/Ni@GDY.Cu/Ni@GDY requires an overpotential(−0.61 V)to 10 mA/cm^(2) for the formation of CO,and it shows better activity than Au and Ag,achieving a higher Faraday efficiency of about 95.2%and high stability of about 26 h at an overpotential(−0.70 V).The electronic interaction between GDY substrate and Cu/Ni alloy NPs and the large specific surface area of GDY is responsible for the high performance.

Microstructure and abrasive wear behaviour of anodizing composite films containing Si C nanoparticles on Ti6Al4V alloy

Anodized composite films containing Si C nanoparticles were synthesized on Ti6Al4 V alloy by anodic oxidation procedure in C4O6H4Na2 electrolyte. Scanning electron microscopy(SEM), energy dispersive spectroscopy(EDS) and X-ray photoelectron spectroscopy(XPS) were employed to characterize the morphology and composition of the films fabricated in the electrolytes with and without addition of Si C nanoparticles. Results show that Si C particles can be successfully incorporated into the oxide film during the anodizing process and preferentially concentrate within internal cavities and micro-cracks. The ball-on-disk sliding tests indicate that Si C-containing oxide films register much lower wear rate than the oxide films without Si C under dry sliding condition. Si C particles are likely to melt and then are oxidized by frictional heat during sliding tests. Potentiodynamic polarization behavior reveals that the anodized alloy with Si C nanoparticles results in a reduction in passive current density to about 1.54×10-8 A/cm2, which is more than two times lower than that of the Ti O2 film(3.73×10-8 A/cm2). The synthesized composite film has good anti-wear and anti-corrosion properties and the growth mechanism of nanocomposite film is also discussed.

Tuning the near room temperature oxidation behavior of highentropy alloy nanoparticles

Understanding the oxidation behavior of high-entropy alloys(HEAs)is essential to their practical applications.Here we conducted in situ environmental transmission electron microscopy(E-TEM)observations of dynamic oxidation processes in CrMnFeCoNi and CrFeCoNiPd nanoparticles(NPs)near room temperature.During the oxidation of CrMnFeCoNi NPs,a favorable oxidation product was MnCr_(2)O_(4)with the spinel structure.The surface nanoislands of MnCr_(2)O_(4)underwent dynamic reconstruction,resulting in the thickened oxide layer with less crystallinity.In CrFeCoNiPd NPs,the reactive element Mn was replaced by the inert element Pd.As a result,a favorable oxide product was CrO_(2)with the rutile structure.CrO_(2)formed on the NP surface and was a result of Cr outward diffusion through the oxide layer.In addition,FeO nanocrystals formed at the oxide/metal interface and were a result of O inward diffusion through the oxide layer.We also performed first principles calculations to provide insights into the energetics and diffusion rates related to oxide formation.These results reveal the non-equilibrium processes of oxidation in HEA NPs that can be strongly influenced by small particle sizes and large surface areas.This work underscores the high tunability of oxidation behavior in nanoscale HEAs by changing their constituent alloying elements.

FeCo alloy@N-doped graphitized carbon as an efficient cocatalyst for enhanced photocatalytic H2 evolution by inducing accelerated charge transfer

Cocatalysts play important roles in improving the activity and stability of most photocatalysts.It is of great significance to develop economical,efficient and stable cocatalysts.Herein,using Na2CoFe(CN)6 complex as precursor,a novel noble-metal-free FeCo@NGC cocatalyst(nano-FeCo alloy@N-doped graphitized carbon) is fabricated by a simple pyrolysis method.Coupling with g-C3 N4, the optimal FeCo@NGC/g-C3N4 receives a boosted visible light driven photocatalytic H2 evolution rate of 42.2 μmol h-1, which is even higher than that of 1.0 wt% Pt modified g-C3N4 photocatalyst.Based on the results of density functional theory(DFT) calculations and practical experiment measurements,such outstanding photocatalytic performance of FeCo@NGC/g-C3N4 is mainly attributed to two aspects.One is the accelerated charge transfer behavior,induced by a photogene rated electrons secondary transfer performance on the surface of FeCo alloy nanoparticles.The other is related to the adjustment of H adsorption energy(approaching the standard hydrogen electrode potential) by the presence of external NGC thin layer.Both factors play key roles in the H2 evolution reaction.Such outstanding performance highlights an enormous potential of developing noble-metal-free bimetallic nano-alloy as inexpensive and efficient cocatalysts for solar applications.

Novel PtPd alloy nanoparticle-decorated g-C_3N_4 nanosheets with enhanced photocatalytic activity for H_2 evolution under visible light irradiation

PtPd bimetallic alloy nanoparticle (NP)-modified graphitic carbon nitride (g-C3N4) nanosheet photocatalysts were synthesized via chemical deposition precipitation. Characterization of the photocatalytic H2 evolution of the g-C3N4 nanosheets shows that it was significantly enhanced when PtPd alloy NPs were introduced as a co-catalyst. The 0.2 wt% PtPd/g-C3N4 composite photocatalyst gave a maximum H2 production rate of 1600.8 μmol g^–1 h^–1. Furthermore, when K2HPO4 was added to the reaction system, the H2 production rate increased to 2885.0 μmol g^–1 h^–1. The PtPd/g-C3N4 photocatalyst showed satisfactory photocatalytic stability and was able to maintain most of its photocatalytic activity after four experimental photocatalytic cycles. In addition, a possible mechanism for the enhanced photocatalytic activity was proposed and verified by various photoelectric techniques. These results demonstrate that the synergistic effect between PtPd and g-C3N4 helps to greatly improve the photocatalytic activity of the composite photocatalyst.

Composition-controlled synthesis of platinum and palladium nanoalloys as highly active electrocatalysts for methanol oxidation

Platinum and palladium(PtPd)alloy nanoparticles(NPs)are excellent catalysts for direct methanol fuel cells.In this study,we developed PtPd alloy NPs through the co‐reduction of K2PtCl4and Na2PdCl4in a polyol synthesis environment.During the reaction,the feed molar ratio of the two precursors was carried over to the final products,which have a narrow size distribution with a mean size of approximately4nm.The catalytic activity for methanol oxidation reactions possible depends closely on the composition of as‐prepared PtPd alloy NPs,and the NPs with a Pt atomic percentage of approximately75%result in higher activity and stability with a mass specific activity that is7times greater than that of commercial Pt/C catalysts.The results indicate that through composition control,PtPd alloy NPs can improve the effectiveness of catalytic performance.

Electrodeposited PtNi nanoparticles towards oxygen reduction reaction:A study on nucleation and growth mechanism

In this work,highly monodispersed Pt-Ni alloy nanoparticles were directly deposited on carbon substrate through a facile electrodeposition strategy in the solvent system of N,N-dimethylformamide(DMF).A series of carbon supported Pt-Ni alloy electrocatalysts were synthesized under different applied electrode potentials.Among all as-obtained samples,the Pt-Ni/C electrocatalyst deposited at-1.73 V exhibits the optimal specific activity up to 1.850 mA cm^(-2)at 0.9 V vs.RHE,which is 6.85 times higher than that of the commercial Pt/C.Comprehensive physiochemical characterizations and computational evaluations via density functional theory were conducted to unveil the nucleation and growth mechanism of PtNi alloy formation.Compared to the aqueous solution,DMF solvent molecule must not be neglected in avoiding particle agglomeration and synthesis of monodispersed nanoparticles.During the alloy co-deposition process,Ni sites produced through the reduction of Ni(Ⅱ)precursor not only facilitates Pt-Ni alloy crystal nucleation but also in favor of further Pt reduction on the Ni-inserted Pt surface.As for the deposition potential,it adjusts the final particle size.This work provides a hopeful extended Pt-based catalyst layer production strategy for proton exchange membrane fuel cells and a new idea for the nucleation and growth mechanism exploration for electrodeposited Pt alloy.

ZnO nanorod decorated by Au-Ag alloy with greatly increased activity for photocatalytic ethylene oxidation

In recent years, the preservation of fruits and vegetables in cold storage has become an issue of increasing concern, ethylene plays a leading role among them. We found ZnO has the effect of degrading gaseous ethylene, however its effect is not particularly satisfactory. Therefore, we used simple photo-deposition procedure and low-temperature calcination method to synthesize Au, Ag, and Au Ag alloy supported ZnO to improve the photocatalytic efficiency. Satisfactorily, after ZnO loaded with sole Au or Ag particles, the efficiency of ethylene degradation was 17.5 and 26.8 times than that of pure ZnO, showing a large increase in photocatalytic activity. However, the photocatalytic stability of Ag/ZnO was very poor, because Ag can be easily photooxidized to Ag2O. Surprisingly, when ZnO was successfully loaded with the Au Ag alloy, not only the photocatalytic activity was further improved to 94.8 times than that of pure ZnO, but also the photocatalytic stability was very good after 10 times of cycles. Characterization results explained that the Au-Ag alloy NPs modified ZnO showed great visible-light absorption because of the surface plasmon resonance(SPR) effect. Meanwhile, the higher photocurrent density showed the effective carrier separation ability in Au Ag/ZnO. Therefore, the cooperative action of plasmonic Au Ag bimetallic alloy NPs and efficient carrier separation capability result in the outstanding photoactivity of ethylene oxidation. At the same time, the formation of the alloy produced a new crystal structure different from Au and Ag, which overcomes the problem of poor stability of Ag/ZnO, and finally obtains Au Ag/ZnO photocatalyst with high activity and high stability. This work proposes a new concept of using metal alloys to remove ethylene in actual production.

Recent advances in the synthesis and fabrication methods of high-entropy alloy nanoparticles

High-entropy alloy nanoparticles(HEA NPs)containing four or more elements possess several advantages over traditional alloy nanoparticles(NPs),such as higher strength,greater thermal stability,enhanced ox-idation resistance,stronger catalytic activity,and greater flexibility in adjusting element composition and composition ratio.However,the development of HEA NPs has been limited by preparation difficulties caused by the challenge of achieving complete miscibility between multiple-component elements and the unique high-entropy states.In this review,we provide a comprehensive summary of recent break-throughs in synthesizing and fabricating HEA NPs.We describe the experimental procedures and princi-ples of various synthesis methods,including furnace pyrolysis,carbothermal shock(CTS)method,pulse laser,solvothermal method,microwave heating,hydrogen spillover-driven,sputtering deposition,anneal-ing on mesoporous materials,arc discharge methods and using liquid metal.Additionally,we delve into recent improvements made to some of these methods or novel NPs synthesized using them.Finally,we review the current applications of HEA NPs and provide insights into potential applications of this rapidly emerging research field.