(4nf) Electrochemical Manufacturing of Valuable Liquid Fuels and Product Upgrading By CO2 Gas Reduction Reaction (CO2RR) and Reactor Design

The electrochemical CO₂ reduction reaction (CO₂RR) to valuable chemicals and liquid fuels using renewable electricity is a practically approachable method for carbon neutrality. However, developing electrochemical systems for generating selective C₂₊ products, such as ethylene and acetate, still needs to be improved because most reaction pathways overlap with each C₂₊ product. Selectively producing ethanol, a liquid fuel with high energy density and industrial demands, is especially challenging due to its low selectivity, low activity, poor stability, and mixing with liquid electrolytes in traditional CO₂ electrolyzers. Even if the electrocatalysts showed improved ethanol selectivity, achieving stable operation even longer than 20 hours using conventional electrolyzers was particularly difficult. Additionally, electrochemical CO₂/CO reduction has intrinsic limitations to producing C₄₊ products over C₂ or C₃ products. It is getting extremely challenging to produce high-value hydrocarbons with longer C₃ products when only the electrochemical reduction reaction is applied. This research suggests a new reactor design to promote further upcycling of the waste/harmful gas into valuable materials (C₄₊), an important transition pathway into sustainable energy engineering.

Herein, we developed a grain boundary-rich zinc-doped Cu₂O electrocatalyst that presented high ethanol Faradaic efficiency of over 40 % under a current density of 350 mA·cm^-2. Furthermore, we employed the developed catalyst in our porous solid electrolyte (PSE) reactor with careful salt management design to demonstrate the stable generation of high-purity ethanol solution directly from electrolysis. By co-flowing CO₂ gas and DI water droplets with an optimized flow rate into the cathode side, we can facilitate the stable CO₂RR under 250 mA·cm^-2 while showing about 30 FE % of ethanol for 180 hours. Additionally, we demonstrated a PSE reactor producing highly selective and pure acetate coupled with the biosynthesis system to generate C₄₊ polyhydroxybutyrate (PHB) bioplastic. A silver-doped Cu₂O nanocube electrocatalyst was carefully tuned for high selectivity towards acetate other than alcohols, which resulted in over 150 mM (with over 55 % Faradaic efficiency) of high-purity acetic acid product. With the optimized electrolyte, Ralstonia eutropha bacteria utilized the acetate and produced biomass with approximately 450 mg/L of C₄₊ poly-hydroxybutyrate bioplastic by digesting acetate in 4 days.

Figure Caption: (A) Schematic of a porous solid electrolyte (PSE) reactor with diverse product chains from electro-synthesized acetate. Continuous pure acetic acid and electrolytes for biosynthesis can be generated by flowing DI water and the optimized mineral salt medium through the middle layer, respectively. (B) Schematic of a salt-managing PSE reactor and the ethanol collecting procedure through the PSE layer chamber and cathode side downstream.

Research Interests: Energy Conversion, CO₂ Reduction Reaction (CO₂RR), Energy Storage Systems (ESSs), In-situ/Cryo TEM, Fundamental Mechanism Understanding

Research on energy conversion (i.e., Energy storage systems, CO2 electrocatalytic reduction) by the development of novel materials and systems + Understanding of fundamental reaction mechanisms using the In-situ/Cryogenic TEM technique. Fundamental understandings play critical roles in developing practical applications, ranging from renewable energy conversion and chemicals/fuels production in new energy systems.

Teaching Interests: Based on my background, I will teach knowledge from nanometer-scale material analysis for reaction mechanism studies to meter-scale electrochemical device engineering for practical development. This can provide scientific evidence for problem-solving approaches at the front line as future research leaders in diverse fields grow.