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,*, and Xin Wang4,*
1 Soochow Univ, Coll Chem Chem Engn & Mat Sci, Innovat Ctr Chem Sci, Suzhou 215006, Jiangsu, Peoples R China
2 Soochow Univ, Jiangsu Key Lab Adv Negat Carbon Technol, Suzhou 215123, Jiangsu, Peoples R China
3 Suzhou Univ Sci & Technol, Sch Chem & Life Sci, Suzhou 215009, Jiangsu, Peoples R China
4 City Univ Hong Kong, Dept Chem, Hong Kong 999077, Peoples R China
Angew. Chem. Int. Ed.2024, e202416274
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.
链接：https://onlinelibrary.wiley.com/doi/10.1002/anie.202416274
