Rare Earth Embedding Strategy Promotes the Concentration Increase of Oxygen Vacancies in FePr 0.2 /CNTs for Anion Exchange Membrane Water Electrolysis

ABSTRACT It is extremely challenging to precisely control the formation of oxygen vacancies through rare earth elements with rich electronic structures. In this work, a Fe 3 O 4 /Pr 2 O 3 heterojunction was successfully fabricated in carbon nanotubes through a rare earth embedding strategy. The increase in the concentration of oxygen vacancies in the heterojunction was utilized to optimize the valence state and coordination structure of the Fe active sites. The results of XPS, XAS, and DFT confirmed that the increase in oxygen vacancy concentration helps Fe atoms acquire a new coordination environment and high valence state. This enables Fe active sites to have the best adsorption ability and the lowest RDS reaction energy barrier. Based on this, FePr 0.2 /CNTs exhibited the best OER activity. Its overpotential is only 270 mV at 100 mA cm −2 . More importantly, as a carbon‐based catalyst, FePr 0.2 /CNTs can operate stably in AEMWE for over 400 h (kept at 1.58 V at 500 mA cm −2 ). The average voltage growth rate is only 0.1041 mV per hour. This paper examines the influence of the coordination environment of Fe atoms on the OER activity from the perspective of oxygen vacancies, and also provides new possibilities for the design of carbon‐based catalysts in AEMWE.