Hierarchically Coupled Ni:FeOOH Nanosheets on 3D N‑Doped Graphite Foam as Self-Supported Electrocatalysts for Efficient and Durable Water Oxidation

• Published in: ACS catalysis 2019-06, Vol.9 (6), p.5025-5034
• Main Authors: Suryawanshi, Mahesh P, Ghorpade, Uma V, Shin, Seung Wook, Suryawanshi, Umesh P, Jo, Eunae, Kim, Jin Hyeok
• Format: Article
• Language: English
• ISSN: 2155-5435; 2155-5435
• DOI: 10.1021/acscatal.9b00492

Here, a hierarchical nanostructure composed of Ni-doped α-FeOOH (Ni:FeOOH) nanosheets coupled with N-doped graphite foam (NGF) is demonstrated as a three-dimensional (3D) self-supported electrocatalyst for highly efficient and durable water oxidation. A facile, one-step directional growth of catalytically active Ni:FeOOH nanosheets on highly conducting 3D NGF results in a fully integrated, hierarchical, nanostructured electrocatalyst with (i) the high intrinsic activity of Ni:FeOOH, (ii) the outstanding electrical conductivity of NGF, and (iii) a well-defined porous structure with an enhanced active surface area. As a result, the self-supported 3D Ni:FeOOH/NGF electrocatalyst exhibits remarkable electrocatalytic activity for the oxygen evolution reaction (OER) in an alkaline solution with an overpotential of 214 mV at 10 mA/cm2, a high stability for over 60 h, a low Tafel slope of 36.2 mV dec–1, and a capability of delivering a high current density of 300 mA/cm2 at an overpotential of 368 mV. In contrast to photodeposition, electrodeposition, and hydrothermal methods for the formation/integration of (oxy)­hydroxides, this facile solution strategy for designing an attractive and efficient structure with a highly active metal (oxy)­hydroxide and highly conducting NGF provides a pathway to develop other earth-abundant electrocatalysts for a multitude of energy-conversion-device applications.