Dual-sized NiFe layered double hydroxides in situ grown on oxygen-decorated self-dispersal nanocarbon as enhanced water oxidation catalysts

Abstract

The oxygen evolution reaction (OER) is extensively involved in various sustainable energy processes and systems, such as water splitting, fuel cells, and metal–air batteries. Towards superior OER performance, the wise integration of transition metal compounds with nanocarbon materials is a promising strategy. Herein, a mildly oxidized graphene/single-walled carbon nanotube hybrid was introduced to regulate and control the hybridization of nickel–iron layered double hydroxides into a nanocarbon scaffold. The oxygen functionalities and defects anchored the nucleation and in situ growth of dual-sized layered double hydroxides, leading to a hierarchical porous structure for smooth mass diffusion, intimate interfaces for rapid charge transfer, and efficiently utilized active sites. Attributed to the synergy of individual components and the unique structural features, the as-fabricated composites exhibited superior OER performance with a small onset overpotential (ca. 240 mV), a low overpotential required for 10 mA cm⁻² (ca. 350 mV), and a decreased Tafel slope (ca. 54 mV dec⁻¹) in 0.10 M KOH. This work provides a brilliant catalyst for water oxidation and more importantly, opens up new avenues for preparing nanocarbon-based multi-functional composites applicable in heterogeneous catalysis, energy conversion and storage, and so on.