Scalable flame spray-derived bismuth catalysts enable efficient CO2 electrolysis revealed by FIB-SEM nano-tomography and ICP-MS EDX profiling
The paper authored by
A. Rieder, H. Rabiee, F. Lorenzutti, P. Willi, L. Warmuth,
S. Vesztergom,
R. Grass, W. Stark, S. Haussener and P. Broekmann
is published in Cell Reports Physical Science (2026, 7, 103500).
Abstract:
CO2 electrolysis is a promising route to convert CO2 into value-added chemicals. Here, we use flame spray pyrolysis (FSP) as a rapid and scalable method to synthesize Bi2O3 nanospheres and evaluate their formate production in a gas diffusion electrode flow electrolyzer. Under reaction conditions, Bi2O3 converts in situ into bismuth subcarbonate, delivering >90% formate Faradaic efficiency across −0.6 to −1.6 V vs. reversible hydrogen electrode (RHE), reaching a formate partial current density of −700 mA.cm−2 at −1.8 V. This performance is nearly twice that of electrochemically deposited dendritic Bi2O3. To elucidate the origin of this high performance, a combined tomography approach based on focused ion beam-scanning electron microscopy (FIB-SEM) nano-tomography and inductively coupled plasma-mass spectrometry (ICP-MS) EDX cross-sectional profiling was introduced to track catalyst layer morphology and electrolyte-induced flooding. The FSP-derived catalyst forms a compact layer near the microporous layer, confining flooding to the catalyst microporous interface and improving operational stability. This work provides mechanistic insight and characterization guidelines for designing durable, high-performance electrodes for CO2 electrolysis.