Stabilization of High-Valent Molecular Cobalt Sites through Oxidized Phosphorus in Reduced Graphene Oxide for Enhanced Oxygen Evolution Catalysis
Jiahui Yang1,2, Guoliang Dai3, Wenjuan Song1, Poe Ei Phyu Win1,2, Jiong Wang1,2（王炯）*, Xin Wang4（王昕）*
1Innovation Center for Chemical Science, College of Chemistry, Chemical Engineering and Materials Science Soochow University Suzhou 215006, Jiangsu, P. R. China
2Jiangsu Key Laboratory of Advanced Negative Carbon Technologies Soochow University Suzhou, 215123, Jiangsu, P.R. China
3School of Chemistry and Life Sciences Suzhou University of Science and Technology Suzhou 215009, Jiangsu, P. R. China
4Department of Chemistry City University of Hong Kong Hong Kong, 999077, P. R. China
Angew. Chem. Int. Ed. 2025, 64, e202416274
Abstract: Heterogeneous molecular cobalt (Co) sites represent one type of classical catalytic sites for electrochemical oxygen evolution reaction (OER) in alkaline solutions. There are dynamic equilibriums between Co2+, Co3+ and Co4+ states coupling with OH−/H+ interaction before and during the OER event. Since the emergence of Co2+ sites is detrimental to the OER cycle, the stabilization of high-valent Co sites to shift away from the equilibrium becomes critical and is proposed as a new strategy to enhance OER. Herein, phosphorus (P) atoms were doped into reduced graphene oxide to link molecular Co2+ acetylacetonate toward synthesizing a novel heterogeneous molecular catalyst. By increasing the oxidation states of P heteroatoms, the linked Co sites were spontaneously oxidized from 2+ to 3+ states in a KOH solution through OH− ions coupling at an open circuit condition. With excluding the Co2+ sites, the as-derived Co sites with 3+ initial states exhibited intrinsically high OER activity, validating the effectiveness of the strategy of stabilizing high valence Co sites.
Article information: //doi.org/10.1002/anie.202416274
