Date of Award


Document Type


Degree Name

Master of Science (MS)


Materials Science and Engineering

Committee Chair/Advisor

Kai He

Committee Member

Jianhua Tong

Committee Member

Ming Tang


In the past years, there has been an increasing interest in synthesizing Pt alloy nanocrystals to achieve high catalytic performance for energy-related applications. Pt-Ni nanoparticles (NPs) have shown high electrocatalytic activity for electrocatalysis and thermal catalysis. However, the stability of surface structures and compositions still needs to be improved to obtain better long-term catalytic stability. It is noted that thermal annealing can adjust the surface structures and compositions to improve the stability. Transmission electron microscopy (TEM) plays a vital role in characterizing the morphology, structure, and composition of nanoparticles. Specifically, the utilization of in situ TEM can allow for observing the real-time evolution of materials transformation during dynamic processes or reactions. This thesis focuses on the synthesis of bimetallic Pt-Ni NPs and the underlying growth and transformation mechanism through advanced TEM characterizations including in situ TEM. Single-crystalline Pt-Ni nanoparticles in truncated octahedral shape through solution-phase synthesis have been successfully produced. We have studied the variations of reaction temperature, compositions of precursors and reaction time on the NPs’ morphology and structure. With the help of in situ TEM, the dynamic morphology evolution of Pt-Ni NPs under thermal annealing conditions was discovered and the associated transformation mechanism was also elucidated. This study shows implications for the design of catalytically effective nanocrystal geometry of Pt-Ni bimetallic catalysts.

Author ORCID Identifier




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