Element segregation and thermal stability of Ni-Rh nanoparticles

YS Xu and G Wang and P Qian and YJ Su, JOURNAL OF SOLID STATE CHEMISTRY, 311, 123096 (2022).

DOI: 10.1016/j.jssc.2022.123096

A new angular-dependent potential (ADP) of Ni-Rh system was obtained by fitting the experimental data and first principle data, and the effectiveness of the potential was tested. Then, the element segregation characteristics and thermal stability of Ni-Rh nanoparticles were studied by Monte Carlo and molecular dynamics. The results show that the chemical ordering pattern of Ni1-xRhx nanoparticles is the result of the competition of surface energy, strain energy, interface energy and bond energy. With the increase of x, Rh atoms are preferentially segregated to the surface and dispersed. The concentration of Rh atoms in the surface decreases with the increase of size or temperature. With the increase of x, the melting point of Ni1-xRhx nanoparticle first gradually increased, reached the highest near x = 0.1, then gradually decreased, reached the lowest near x = 0.5, and then gradually increased. The above results theoretically explain the reason why doping a small amount of Rh can improve the coking resistance and sintering- resistance ability of Ni catalyst.

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