Imaging Single Nanobubbles of H₂ and O₂ During the Overall Water Electrolysis with Single-Molecule Fluorescence Microscopy

Abstract

In this work, we describe the preparation and use of a thin metal film modified Indium Tin Oxide (ITO) electrode as a highly conductive, transparent, and electrocatalytically active electrode material for studying nanobubbles generated at the electrode/solution interface. Hydrogen and oxygen nanobubbles were generated from water electrolysis on the surface of a Au/Pd alloy modified ITO electrode. The formation of single H2 and O2 nanobubbles was imaged in real time during a potential scan using single-molecule fluorescence microscopy. Our results show that while O2 nanobubbles can be detected at an early stage in the oxygen evolution reaction (OER), the formation of H2 nanobubbles requires a significant overpotential. Our study shows that thin-film-coated ITO electrodes are simple to make and can be useful electrode substrates for (single molecule) spectroelectrochemistry research.

Single‐Molecule Fluorescence Imaging of Nanocatalysis

“…However, it is difficult to image O 2 nanobubbles on ITO because of the inertness of ITO in electrocatalytic reactions. [ 46 ] In their recent work, [ 47 ] by adding an Au/Pd film on an ITO surface (Au/Pd‐ITO) to enhance its catalytic activity, they successfully observed both the H 2 and O 2 nanobubbles from water electrolysis with single molecule nanobubbles labeling approach. Figure 7a showed the experimental setup for gas nanobubbles imaging with Rhodamine 6G (R6G) applied for nanobubble labeling.…”

“…(f, j) Typical fluorescence images and corresponding fluorescence intensity versus time trajectories detected at 0.1 V (f) and –1.5 V (j). [ 47 ]…”

Recent progress in gas nanobubble electrochemistry

“…Pd合金纳米粒子, 同时实现了H 2 和O 2 纳米气泡的荧光 成像 [89] . 暗场散射显微镜(DFM)主要通过测量样本的瑞利 散射信号进行成像, 有样本区域具有较强的散射强度, 并且与样本尺寸、形貌及化学组成相关 [78] .…”

Role of bulk nanobubbles in removing organic pollutants in wastewater treatment

“…At present, with the advancement of research, several methods, including direct immersion, temperature changes, electrochemical reactions, and ethanol–water exchange, have been applied to generate surface nanobubbles (Qiu et al 2017 ), which are used for surface cleaning, and micro-scale pipeline design; however these technologies are not yet well developed. Bulk nanobubbles produced by the electrolytic method (Hao et al 2020 ), the porous membrane method (Ulatowski et al 2019 ), sonication cavitation (Ulatowski et al 2019 ), and hydrodynamic cavitation (Oliveira et al 2018 ), on the other hand, play a predominant role in water treatment.…”