In situ formation of molecular Ni-Fe active sites on heteroatom-doped graphene as a heterogeneous electrocatalyst toward oxygen evolution

Jiong Wang; Liyong Gan; Wenyu Zhang; Yuecheng Peng; Hong Yu; Qingyu Yan; Xinghua Xia; Xin Wang

doi:10.1126/sciadv.aap7970

In situ formation of molecular Ni-Fe active sites on heteroatom-doped graphene as a heterogeneous electrocatalyst toward oxygen evolution

Sci Adv. 2018 Mar 9;4(3):eaap7970. doi: 10.1126/sciadv.aap7970. eCollection 2018 Mar.

Authors

Jiong Wang¹, Liyong Gan², Wenyu Zhang¹, Yuecheng Peng¹, Hong Yu³, Qingyu Yan³, Xinghua Xia⁴, Xin Wang¹

Affiliations

¹ School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, Singapore 637459, Singapore.
² School of Material Science and Engineering, Key Laboratory of Advanced Energy Storage Materials of Guangdong Province, South China University of Technology, Guangzhou 510641, China.
³ School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore.
⁴ School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210046, China.

Abstract

Molecularly well-defined Ni sites at heterogeneous interfaces were derived from the incorporation of Ni²⁺ 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 Fe³⁺ 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^- ions with a bridge geometry, which facilitated the OER electrocatalysis.

Publication types

Research Support, Non-U.S. Gov't