La- and Mn-doped cobalt spinel oxygen evolution catalyst for proton exchange membrane electrolysis

• Published in: Science (American Association for the Advancement of Science) Vol. 380; no. 6645; pp. 609 - 616
• Main Authors: Chong, Lina, Gao, Guoping, Wen, Jianguo, Li, Haixia, Xu, Haiping, Green, Zach, Sugar, Joshua D., Kropf, A. Jeremy, Xu, Wenqian, Lin, Xiao-Min, Xu, Hui, Wang, Lin-Wang, Liu, Di-Jia
• Format: Journal Article
• Language: English
• Published: United States The American Association for the Advancement of Science 12.05.2023; AAAS
• Subjects: Acidic oxides; Catalysts; Cobalt; Cobalt oxides; Electrolysis; Hydrogen production; Iridium; Lanthanum; Manganese; Manganese ions; MATERIALS SCIENCE; Membranes; OER catalyst; Oxidation; PEM; Protons; water splitting
• ISSN: 0036-8075; 1095-9203; 1095-9203
• DOI: 10.1126/science.ade1499

Discovery of earth-abundant electrocatalysts to replace iridium for the oxygen evolution reaction (OER) in a proton exchange membrane water electrolyzer (PEMWE) represents a critical step in reducing the cost for green hydrogen production. We report a nanofibrous cobalt spinel catalyst codoped with lanthanum (La) and manganese (Mn) prepared from a zeolitic imidazolate framework embedded in electrospun polymer fiber. The catalyst demonstrated a low overpotential of 353 millivolts at 10 milliamperes per square centimeter and a low degradation for OER over 360 hours in acidic electrolyte. A PEMWE containing this catalyst at the anode demonstrated a current density of 2000 milliamperes per square centimeter at 2.47 volts (Nafion 115 membrane) or 4000 milliamperes per square centimeter at 3.00 volts (Nafion 212 membrane) and low degradation in an accelerated stress test. Water electrolysis is a potentially sustainable means of producing hydrogen. Unfortunately, only rare and expensive iridium is a sufficiently stable and active oxidation catalyst in the most efficient acidic environment. Chong et al . now report that doping an Earth-abundant cobalt oxide catalyst with lanthanum and manganese ions promotes activity and stability in an acidic proton-exchange membrane water electrolyzer. Simulations suggest that the lanthanum stabilizes the surface of the catalyst and the manganese enhances conductivity in the bulk. —Jake Yeston Doping a cobalt oxide with lanthanum and manganese produces an acid-stable oxygen evolution catalyst free of precious metals.