> ## Content Index > Fetch the complete content index at: https://research-pop.com/llms.txt > Use this file to discover other available public pages before exploring further. # Arizona State University team tests nanobubbles as a CO2 supply for electrochemical formate production - URL: https://research-pop.com/arizona-state-university-team-tests-nanobubbles-as-a-co2-supply-for-electrochemical-formate-production/ - Published: 2026-09-17T12:28:03.000Z - Updated: 2026-09-17T12:38:16.000Z - Author: ResearchPOP - Tags: Chemistry, Energy ![](https://storage.ghost.io/c/7c/5e/7c5e0911-739b-4a35-94eb-3e810bf78ba7/content/images/2026/09/Screenshot-2026-09-17-at-14.10.46.png) **Source**: [https://doi.org/10.1021/jacs.6c13561](https://doi.org/10.1021/jacs.6c13561?ref=research-pop.com) ## At a glance CO2 electroreduction depends not only on the electrode but also on how CO2 reaches it. Aaron Z. Hoagland and colleagues coupled a nanobubble generator to a tin-cathode H-cell and compared it with conventional macrobubbling. With an air-sealed headspace at 5 mA cm^-2, four-hour formate yields were 1,157 and 348 mmol m^-2, respectively. Under continuous CO2 delivery, nanobubbles produced a 2.7-fold higher kinetic formate-production rate than continuous macrobubbling. The study focuses on maintaining CO2 supply to the electrode when its availability in the aqueous electrolyte becomes limiting. By comparing nanobubbles and conventional macrobubbles in the same laboratory electrochemical system, the researchers track bubble formation and stability alongside formate production, Faradaic efficiency and performance at higher current densities. ## Background Electrochemical CO2 reduction occurs at an interface. CO2 must move from the gas phase, through the liquid electrolyte and toward the cathode before it can react. Its limited solubility in water means that reactant delivery can constrain the process even when an active catalyst is present. Nanobubbles are small gas-containing interfaces that can remain suspended in liquid longer than conventional larger bubbles. This makes them a potential means of maintaining CO2 availability in the electrolyte. The researchers used a tin cathode and an H-type cell to compare the two delivery modes while keeping the electrode and other parts of the electrochemical system consistent. ## Research question The study examines whether CO2 nanobubbles can be generated and sustained in bicarbonate electrolyte and whether they increase formate production relative to conventional macrobubbling. The researchers evaluate the influence of the gas headspace, compare batch and continuous CO2 delivery, and test how both delivery modes respond as the current density increases. ## Inside the study The team connected a nanobubble generator, reservoir and circulation loop to an H-type electrochemical cell. The tin cathode operated in 0.5 M KHCO3, and formate was quantified during four-hour experiments. The system could be operated after an initial gas-loading step or with CO2 continuously supplied throughout electrolysis. Nanobubbles formed in both water and bicarbonate electrolyte. In the electrolyte, their concentration briefly approached 6 × 10^8 particles per milliliter before stabilizing near 4 × 10^8 particles per milliliter. Their mean measured diameter was approximately 110 ± 10 nm in the electrolyte, compared with 132 ± 3 nm in water. The gas composition above the liquid influenced nanobubble stability. During a four-hour test without current, nanobubble counts decreased by approximately 45% under a continuous air headspace and by 29% when air was sealed above the liquid. A CO2-rich headspace maintained the nanobubble population more effectively. The authors connect this behaviour with the gas partial pressure above the solution. In batch electrolysis at 5 mA cm^-2 with an air-sealed headspace, the four-hour formate yield reached 1,157 mmol m^-2 with nanobubbles and 348 mmol m^-2 with conventional bubbling, corresponding to an approximately 3.3-fold difference. With CO2 in the headspace, the respective yields increased to 1,672 and 475 mmol m^-2\. Nanobubble counts gradually approached the background level during batch electrolysis, while formate continued to accumulate for longer under the nanobubble condition. The authors also compare kinetic production rates across the batch experiments. Under the specified batch conditions used for that analysis, the nanobubble system reached a 4.7-fold higher kinetic rate. Together with the matched four-hour yield comparisons, these measurements show how headspace composition and operating mode shape the observed improvement. Continuous gas delivery maintained the supply throughout electrolysis. With a CO2 headspace, four-hour formate yields reached approximately 2,558 mmol m^-2 with nanobubbles and 1,011 mmol m^-2 with conventional bubbling. Continuous nanobubble generation sustained a concentration of approximately 4.5 × 10^8 particles per milliliter and produced a 2.7-fold higher kinetic formate-production rate than continuous macrobubbling. Increasing the current density revealed how the delivery methods respond as CO2 consumption rises. In the H-cell, conventional macrobubbling approached mass-transfer limitation at approximately 10–25 mA cm^-2, while the nanobubble condition approached this region near 50 mA cm^-2\. At 50 mA cm^-2, the reported formate-production rates were 0.550 mmol m^-2 s^-1 with nanobubbles and 0.210 mmol m^-2 s^-1 with conventional bubbling. At 5 mA cm^-2, formate Faradaic efficiencies were 68.37% and 26.58%, respectively. ## Takeaways and outlook The results show how gas-delivery conditions influence formate electrosynthesis on a tin cathode. Nanobubbles remained suspended in the bicarbonate electrolyte, their stability responded to the gas headspace, and their use increased formate production and Faradaic efficiency under the tested conditions. Continuous nanobubble generation also extended the current-density range before mass-transfer limitation became prominent. The authors attribute this behaviour to improved CO2 availability near the electrode and present nanobubble engineering as a way to address gas supply in aqueous electrochemical systems. Future studies can further examine how bubble size, concentration, interfacial behaviour and reactor configuration control reactant transport. ## About the researchers Aaron Z. Hoagland (Arizona State University; first-listed author) Andrea N. Arias-Sanchez (Arizona State University) Maria Gomez-Mingot (Arizona State University; Collège de France and Sorbonne Université; corresponding author) Sergi Garcia-Segura (Arizona State University; corresponding author) ## Original research Aaron Z. Hoagland, Andrea N. Arias-Sanchez, Maria Gomez-Mingot and Sergi Garcia-Segura. “Overcoming Challenges and Limitations of Electrochemical Gas-Starved Systems: Nanobubble-Engineered Enhancement of the CO2 Reduction Reaction.” *Journal of the American Chemical Society*, published online 17 September 2026\. DOI: 10.1021/jacs.6c13561\. [Journal article](https://pubs.acs.org/doi/10.1021/jacs.6c13561?ref=research-pop.com) --- ## Research POP Notes This article reflects the independent interpretation of the Research POP team and does not represent the views of the authors, their institutions or the journal. If you identify any inaccuracies or have concerns regarding the content, figures or attribution, please contact us at [team.researchpop@gmail.com](mailto:team.researchpop@gmail.com). We will review the matter promptly and make corrections or remove the relevant material where appropriate.