Overcoming surface inertness: ionic amphiphile-directed selective platinum nucleation on boron nitride nanotubes

Precise integration of metal nanoparticles with chemically inert nanomaterials remains a central challenge in hybrid nanostructure synthesis, as the lack of interfacial reactivity fundamentally limits surface-directed nucleation. In particular, boron nitride nanotubes (BNNTs)-despite their exceptional thermal stability and chemical robustness-exhibit weak interactions with metal precursors, which typically results in uncontrolled homogeneous nucleation in the bulk solution rather than selective growth on the nanotube surface. Here, we demonstrate a highly effective ionic amphiphile-directed nucleation strategy to achieve high-density, uniform growth of platinum (Pt) nanoparticles on BNNTs without destructive covalent functionalization. The introduction of an anionic amphiphile, sodium dodecyl sulfate (SDS), into a polyol reduction system fundamentally reprograms the liquid-solid interface. We elucidate a pivotal dual mechanism: the hydrophobic surfactant tails adsorb onto the BNNT surface to drive localized precursor accumulation via enhanced wetting, while the charged headgroups modulate the interfacial ionic environment. This synergistic modulation lowers the thermodynamic barrier for heterogeneous nucleation and effectively suppresses bulk homogeneous nucleation. Consequently, this strategy yields highly crystalline Pt nanoparticles with narrow size distributions and systematically tunable metal loading up to ~47 wt%. Ultimately, this work establishes a versatile design principle for functionalizing chemically inert surfaces, offering a robust pathway for constructing advanced metal-hybrid architectures where conventional deposition strategies fail.