Reversibly Redox-Active Iron Oxide Structures in FeNC Catalysts Identified by Microscopy and Spectroelectrochemical EPR and Mössbauer Methods - Kaltum Abdiaziz; Lingmei Ni; Derya Demirbas; Hendrik Haak; Edward Reijerse; Pascal Theis; Wulyu Jiang; Sonia Chabbra; Thomas Lunkenbein; Ulrike I. Kramm; Alexander Schnegg (Journal of the American Chemical Society, 2026)