Geometry controlled transition between tip and root growth in Au catalyzed SnO₂nanowires

Understanding the growth mechanism of metal oxide nanowires remains challenging due to the complex interplay among catalyst phase behavior, interfacial energetics, and mass transport. Here, we propose a framework for understanding SnOnanowire growth by elucidating the coexistence of, and transition between tip-growth- and root-growth-dominated vapor-liquid-solid (VLS) mechanisms. By engineering catalyst configurations using Au nanoparticles, Au thin films, and hybrid structures, we establish a direct correlation between catalyst geometry and nanowire morphology. The nanowires exhibit a highly crystalline rutile SnOphase with lattice parameters of,. High-resolution TEM confirms their single-crystalline structure, with an interplanar spacing ofcorresponding to the (-1-10) planes. The morphology strongly depends on the catalyst configuration, with diameters ranging from 20 nm toand lengths ranging fromto over. XPS analysis reveals that the Snfraction increases fromto, suggesting an increasingly oxygen-deficient surface chemical environment associated with catalyst-driven growth kinetics. COMSOL simulations are used to estimate Sn vapor transport and provide order-of-magnitude agreement with the experimentally observed nanowire length of(). This work demonstrates the importance of regulating the transition between tip- and root-growth regimes and provides a conceptual framework in which interfacial effects and catalyst geometry are considered additional factors beyond conventional supersaturation.