Effect of Nonuniform Mass Transport on Nanobubble Nucleation at Individual Pt Nanoparticles,The Journal of Physical Chemistry C

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Effect of Nonuniform Mass Transport on Nanobubble Nucleation at Individual Pt Nanoparticles
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2021-09-08 , DOI: 10.1021/acs.jpcc.1c05020
Nicholas S. Georgescu ₁ , Donald A. Robinson ₁ , Henry S. White ₁

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Understanding nanoscopic bubble nucleation and growth is critical to reducing significant losses in efficiency during water electrolysis or photoelectrochemical hydrogen production. Herein, we demonstrate the controlled nucleation and growth of H₂ nanobubbles at individual Pt nanoparticles (NPs) via the hydrogen evolution reaction (HER) using the dual-barrel mode of scanning electrochemical cell microscopy (SECCM). The NPs, with an average radius of 35 nm, were dispersed on highly oriented pyrolytic graphite (HOPG), an otherwise inert surface, with a spacing much greater than the radius of the probe, allowing for the voltammetric recordings of HER at individual Pt NPs. Finite-element simulations indicate that the concentration of electrogenerated H₂ is highly nonuniform at the NP/solution interface, reaching a maximum at the three-phase HOPG/NP/solution boundary. Using finite-element modeling, we establish a correction factor to estimate the H₂ surface concentration required for nucleation, as determined from the maximum current measured just prior to bubble formation. Furthermore, a drop in ionic current is measured between the two barrels of the SECCM nanopipette upon bubble formation, in agreement with simulations of local conductance when a nanobubble blocks the current path.

中文翻译：

非均匀传质对单个 Pt 纳米粒子纳米气泡成核的影响

了解纳米级气泡的成核和生长对于减少水电解或光电化学制氢过程中效率的显着损失至关重要。在此，我们使用扫描电化学电池显微镜 (SECCM) 的双筒模式通过析氢反应 (HER)证明了 H ₂纳米气泡在单个 Pt 纳米粒子 (NP)上的受控成核和生长。NPs 的平均半径为 35 nm，分散在高度取向的热解石墨 (HOPG) 上，这是一个惰性表面，间距远大于探针的半径，允许在单个 Pt NPs 上进行 HER 的伏安记录. 有限元模拟表明，电生 H ₂的浓度在 NP/溶液界面处高度不均匀，在三相 HOPG/NP/溶液边界处达到最大值。使用有限元建模，我们建立了一个校正因子来估计成核所需的 H ₂表面浓度，这是根据气泡形成前测得的最大电流确定的。此外，在气泡形成时，在 SECCM 纳米移液器的两个桶之间测量到离子电流的下降，这与纳米气泡阻塞电流路径时的局部电导模拟一致。

更新日期：2021-09-16

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