Accelerated directional growth of seaweed-like iron oxide branches driven by localized electric fields of gold nanoparticles in liquid.

Branched nanostructures have attracted significant attention due to their potential applications across diverse fields. Precise control over branched morphology is essential for enhancing their functionality, yet it remains a considerable challenge. In this work, in-situ liquid-cell transmission electron microscopy (LCTEM) is employed to investigate the controllable growth of seaweed-like iron oxide branches in the presence of charged gold nanoparticles (Au NPs) within an organic solution. In contrast to the conventional tip-splitting behavior observed in the absence of Au NPs, the branches exhibit directional and accelerated growth toward the Au NPs without further splitting. Finite-element analysis reveals that the local electric field between the charged Au NPs and the branches promotes reactant aggregation at the branch tips, thereby driving their directional and accelerated growth. This study provides insights into the growth mechanisms of seaweed-like nanostructures and highlights the potential of local electric fields for morphological control of branched structures.