In situ formation of molecular Ni-Fe active sites on heteroatom-doped graphene as a heterogeneous electrocatalyst toward oxygen evolution.
basic_science · Level V
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- Record sourced from PubMed, PMID 29536041.
- Also identified by DOI 10.1126/sciadv.aap7970 and PMC identifier 5844707.
- Licence recorded as CC BY-NC.
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Abstract
Molecularly well-defined Ni sites at heterogeneous interfaces were derived from the incorporation of Ni<sup>2+</sup> ions into heteroatom-doped graphene. The molecular Ni sites on graphene were redox-active. However, they showed poor activity toward oxygen evolution reaction (OER) in KOH aqueous solution. We demonstrated for the first time that the presence of Fe<sup>3+</sup> ions in the solution could bond at the vicinity of the Ni sites with a distance of 2.7 Å, generating molecularly sized and heterogeneous Ni-Fe sites anchored on doped graphene. These Ni-Fe sites exhibited markedly improved OER activity. The Pourbaix diagram confirmed the formation of the Ni-Fe sites and revealed that the Ni-Fe sites adsorbed HO<sup>-</sup> ions with a bridge geometry, which facilitated the OER electrocatalysis.