Data from: Growth and Detachment of Oxygen Bubbles Induced by Gold-Catalyzed Decomposition of Hydrogen Peroxide

Attached file provides supplementary data for linked article. The data consists of three videos - one movie showing the calculated concentration profile of H2O2 across the depth of the liquid over 5 h, one movie showing the calculated concentration profile of O2 across the depth of the liquid over 5 h, one movie of the necking distortion of the bubble root immediately before the detachment - and one PDF, which details calculations of Damköhler number and analyses of the concentration profile.

Whereas bubble growth out of gas-oversatured solutions has been quite well understood, including the formation and stability of surface nanobubbles, this is not the case for bubbles forming on catalytic surfaces due to catalytic reactions, though it has important implications for gas evolution reactions and self-propulsion of micro/nanomotors fueled by bubble release. In this work we have filled this gap by experimentally and theoretically examining the growth and detachment dynamics of oxygen bubbles from hydrogen peroxide decomposition catalyzed by gold. We measured the bubble radius R(t) as a function of time by confocal microscopy and find R(t) ∝ t1/2. This diffusive growth behavior demonstrates that the bubbles grow from an oxygen-oversaturated environment. For several consecutive bubbles detaching from the same position in a short period of time, a well-repeated growing behavior is obtained from which we conclude the absence of noticeable depletion effect of oxygen from previous bubbles or increasing oversaturation from the gas production. In contrast, for two bubbles far apart either in space or in time, substantial discrepancies in their growth rates are observed, which we attribute to the variation in the local gas oversaturation. The current results show that the dynamical evolution of bubbles is influenced by comprehensive effects combining chemical catalysis and physical mass transfer. Finally, we find that the size of the bubbles at the moment of detachment is determined by the balance between buoyancy and surface tension and by the detailed geometry at the bubble’s contact line.

附件文件为关联文章提供补充数据。该数据包含三段视频——一段展示5小时内液体深度方向过氧化氢（H₂O₂）浓度分布计算结果的视频、一段展示5小时内液体深度方向氧气（O₂）浓度分布计算结果的视频、一段记录气泡脱离前瞬间根部颈缩变形的视频——以及一份PDF文件，其中详细说明了达姆科勒数（Damköhler number）的计算过程与浓度分布分析。

尽管气体过饱和溶液（gas-oversaturated solutions）中气泡的生长（包括表面纳米气泡（surface nanobubbles）的形成与稳定性）已得到充分研究，但催化表面（catalytic surfaces）上由催化反应生成的气泡却并非如此——尽管这类气泡对析气反应（gas evolution reactions）及以气泡释放为动力的微/纳米马达（micro/nanomotors）自推进具有重要意义。本研究通过实验与理论分析相结合的方式，探究金催化过氧化氢分解过程中氧气气泡的生长与脱离动力学，填补了这一空白。我们利用共聚焦显微镜（confocal microscopy）测量气泡半径R(t)随时间的变化，发现R(t) ∝ t¹/²。这种扩散生长行为（diffusive growth behavior）表明气泡从氧气过饱和环境中生长。对于短时间内从同一位置连续脱离的多个气泡，其生长行为具有良好的重复性，由此可推断：前序气泡未造成显著的氧气消耗效应，气体生成也未导致过饱和度持续升高。相反，对于空间或时间上相距较远的两个气泡，其生长速率存在显著差异，我们将此归因于局部气体过饱和度的变化。本研究结果表明，气泡的动态演化受化学催化与物理传质综合效应的影响。最后，我们发现气泡脱离瞬间的尺寸由浮力（buoyancy）与表面张力（surface tension）的平衡，以及气泡接触线处的具体几何形态共同决定。