Sintering behavior of Cu-Pd nanoparticles driven by surface atomic diffusion
Bimetallic copper-palladium(Cu-Pd)nanoparticles are a novel type of nanocatalyst.The sintering process of these nanoparticles plays a crucial role in catalytic efficiency through changes in specific surface area and surface composition.To gain a deeper understanding of the sintering mechanism of Cu-Pd bimetallic nanoparticles,this study employed molecular dynamics simulations to investigate the isothermal sintering behavior of 6 nm diameter Cu-Pd heterostructured nanoparticles at various temperatures.The results indicate a correlation between the growth rate of sintering necks and temperature.within the range of(0.5～0.8)Tm(melting temperature),the relationship is linear,Rsn=T/Tm+1.1;while within the range of(＞0.8～1.0)Tm,the growth of sintering necks rapidly accelerates with increasing temperature,showing an approximate exponential relationship,Rsn=35(T/Tm)2-52.5(T/Tm)+21.5.The initial sintering behavior of Cu-Pd nanoparticles is primarily driven by the diffusion of low-melting-point copper surface atoms.Additionally,the relatively low mixing enthalpy facilitates the bonding between Cu and Pd atoms,enhancing the diffusion capability of Pd atoms,driving the continuous inward sintering of Cu-Pd nanoparticles.
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