Strongly coupled N-doped graphene quantum dots/Ni(Fe)OxHy electrocatalysts with accelerated reaction kinetics for water oxidation

[Display omitted] •Strongly coupled NGQDs/Ni(Fe)OxHy composite electrocatalysts were prepared.•The synergistic effect of composite structure modifies the metal charge center.•Highly-active Ni(Fe)–OOH species accelerate the hydroxylation process for OER.•The NGQDs/Ni(Fe)OxHy shows an excellent OER activity with fast reaction kinetics. Hybridization of metal hydroxides with conductive carbon materials is one of the effective strategies to alleviate their poor electron transfer and improve the slow kinetics of oxygen evolution reaction (OER). However, how to realize the stable and effective fabrication of the composite structure is urgently required but still a challenge. In this work, we constructed a novel electrocatalyst that abundant nitrogen-doped graphene quantum dots (NGQDs) are uniformly anchored on Ni(Fe)OxHy nanosheets through the strong M−N−C bonding. The synergistic effect between composite components greatly modifies the metal charge center with higher chemical valence and accelerates the hydroxylation process (*O→*OOH) during OER process. Meanwhile, the smaller apparent activation energy (Ea) and faster proton coupled electron transfer (PCET) verify that the NGQDs/Ni(Fe)OxHy has more favorable reaction kinetics. Consequently, NGQDs/Ni(Fe)OxHy demonstrates an ultralow overpotential of 200 mV at 10 mA cm−2 with a long stability of 36 h. This work provides a viable method to realize the strong combination of carbon materials and metal hydroxides for excellent OER performance.