It is a challenge to study the nucleation of cavitation bubbles, which critically depends on nanoscale morphological features. Our recent advances in synthesizing colloidal negative-curvature nanoparticles (NGC-NPs) offer a rare opportunity, in comparison to the conventional studies of bulk substrates, where it is difficult to obtain consistent and well-defined surface features. In order to quantitatively assess their effects, we exploit the radical-induced color change of [Fe(SCN)], which turned out to be a more convenient method than the bending of AgNWs and the fluorescence-based methods. We show that the NGC-NPs outperform positive-curvature nanoparticles (PSC-NPs) and homogeneous nucleation, in terms of promoting cavitation. The NGC-NPs provide a higher percentage of gas–solid interface, and thus reduces the activation barrier during the critical stage of bubble nucleation. This leads a higher probability of cavitation and transforms more energy from ultrasonication to radical formation and shockwaves.

中文翻译：

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通过负曲率纳米颗粒促进超声空化


研究空化气泡的成核是一个挑战，它很大程度上取决于纳米级的形态特征。与难以获得一致且明确的表面特征的块状基材的传统研究相比，我们最近在合成胶体负曲率纳米颗粒（NGC-NP）方面取得的进展提供了难得的机会。为了定量评估它们的影响，我们利用了 [Fe(SCN)] 自由基引起的颜色变化，事实证明这是一种比 AgNW 弯曲和基于荧光的方法更方便的方法。我们表明，NGC-NP 在促进空化方面优于正曲率纳米颗粒 (PSC-NP) 和均匀成核。 NGC-NPs提供了更高比例的气固界面，从而减少了气泡成核关键阶段的活化势垒。这导致空化的可能性更高，并将更多的能量从超声波转化为自由基形成和冲击波。