Deng Zejun, Renault Christophe
Laboratoire de Physique de la Matière Condensée, Ecole Polytechnique, CNRS, IP Paris Route de Saclay 91128 Palaiseau France
Chem Sci. 2021 Aug 16;12(37):12494-12500. doi: 10.1039/d1sc03646g. eCollection 2021 Sep 29.
Contactless interactions of micro/nano-particles near electrochemically or chemically active interfaces are ubiquitous in chemistry and biochemistry. Forces arising from a convective field, an electric field or chemical gradients act on different scales ranging from few microns down to few nanometers making their study difficult. Here, we correlated optical microscopy and electrochemical measurements to track at the millisecond timescale the dynamics of individual two-dimensional particles, graphene nanoplatelets (GNPs), when approaching an electrified Pt micro-interface. Our original approach takes advantage of the bipolar feedback current recorded when a conducting particle approaches an electrified surface without electrical contact and numerical simulations to access the velocity of individual GNPs. We evidenced a strong deceleration of GNPs from few tens of μm s down to few μm s within the last μm above the surface. This observation reveals the existence of strongly non-uniform forces between tens of and a thousand nanometers from the surface.
在电化学或化学活性界面附近,微/纳米粒子的非接触相互作用在化学和生物化学中普遍存在。对流场、电场或化学梯度产生的力作用于从几微米到几纳米的不同尺度,这使得对它们的研究变得困难。在这里,我们将光学显微镜和电化学测量相结合,以毫秒级的时间尺度跟踪单个二维粒子——石墨烯纳米片(GNP)在接近带电铂微界面时的动力学。我们的原始方法利用了导电粒子在不发生电接触的情况下接近带电表面时记录的双极反馈电流,并通过数值模拟来获取单个GNP的速度。我们证明,在表面上方最后一微米内,GNP从几十微米每秒急剧减速至几微米每秒。这一观察结果揭示了在距离表面几十到一千纳米之间存在强烈的非均匀力。