NiCo-layered double hydroxides vertically assembled on carbon fiber papers as binder-free high-active electrocatalysts for water oxidation

Building nanocomposite architectures made of carbon materials and layered double hydroxides (LDHs) materials as high-efficiency and low-cost catalysts for oxygen evolution reaction (OER) is one of potential strategies for sustainable and clean water splitting. Nevertheless, conventional powder samples, mixed with polymer binders and immobilized on a matrix, suffer from the limited specific surface area and poor conductivity. Herein, a carbon fiber paper (CFP)-assisted strategy is presented to mediate vertical in situ growth and assembly of NiCo-LDH nanoplates, and their catalytic activities as binder-free high-active electrocatalysts for water oxidation were investigated. The CFP is capable of modulating the assembly of NiCo-LDH nanoplates, yielding the vertically oriented nanoarrays on CFP. The as-made hybrids indicate a dramatically increased catalytic activity and long-term stability towards OER in comparison to that of micro-sized LDHs spheres derived from the self-assembly of LDHs nanoplates. A relatively low overpotential of 307 mV is achieved at 10 mA cm−2 and a low Tafel slope of 64 mV dec−1 is delivered in basic medium. The vertically oriented LDHs nanoarrays featuring large specific surface areas, open structure and rich active sites, together with the highly conductive CFP substrate are synergistically responsible for the enhanced electrochemical performance.