A bifunctional hexa-filamentous microfibril multimetallic foam: an unconventional high-performance electrode for total water splitting under industrial operation conditions

Abstract

Cellulose in various forms possesses high strength, low density, and high aspect ratio with a three-dimensional open network structure, making them ideal candidates as current collectors in energy conversion application. Herein, a surface rough-cellulose-based bamboo fiber with unique and naturally-convoluted morphology is adopted for the fabrication of catalytically active cobalt substrates for water splitting. For the efficient evolution of hydrogen and oxygen, cobalt-based bimetallic alloys, namely, cobalt–molybdenum and cobalt–iron, were electrodeposited. The proposed system possesses a highly macro-porous network of hexa-filament micro-fibrils that demonstrate exceptional catalytic activities. In quantitative terms, the anodic and cathodic current density of 50 and −10 mA cm⁻² at respective overpotentials (η) of 250 and 46 mV with a low activation energy (E_a) of 28 kJ mol⁻¹ were achieved. Moreover, when operated under harsh industrial standards of 5 M KOH@343 K, electrodes demonstrate excellent water electrolyzing catalytic activities (η_-100(HER) = 147 mV; η_100(OER) = 209 mV). This work, thus, promises a new strategy for designing electrode systems that are highly efficient as well as economical as the substrate was obtained from a ubiquitous earth-friendly material for energy conversion application.