Mass and charge transfer coenhanced oxygen evolution behaviors in CoFe-layered double hydroxide assembled on graphene

The earth-abundant electrocatalysts with high activity are highly desired and required for high-efficient oxygen evolution reaction (OER). Herein, we report that 2D nanosheet-shaped cobalt-iron-layered double hydroxide (CoFe-LDH) is a highly active and stable oxygen evolution catalyst. The Fe3+ is capable of tailoring the component ranging from hydroxides to LDH and broadening the interlayer space of as-made 2D materials. Benefiting from the synergistic effects between Co and Fe species and the LDH-layered structure, the shortened ion transport distance in the nanoscale dimension, and the broader interlayer space, an enhanced mass transfer behavior for OER is demonstrated. The as-made CoFe-LDH shows high electrocatalytic activity, which is superior to those of corresponding Co(OH)2 and the mixed phase samples of Co(OH)2 and FeOOH, as well as RuO2 and commercial Pt/C catalysts. Assembling CoFe-LDH on reduced graphene oxide (rGO) to configure the 2D sheet-on-sheet binary architectures (CoFe-LDH/rGO) can further create well-interconnected conductive networks within the electrode matrix, leading to the lowest overpotential of 325 mV at 10 mA cm-2. Collectively, such integrated characteristics with alternated components will endow the as-made 2D-structured catalysts with a potential and superb superiority as low-cost earth-abundance catalysts for water oxidation. Integrated hybrids made of CoFe-layered double hydroxide with broad interlayer space and interconnected graphene conductive networks are configured, showing enhanced mass and charge transfer behaviors for oxygen evolution reaction with a low overpotential of 325 mV at 10 mA cm-2. This strategy may pave a new way for design of excellent active and durable oxygen evolution electrocatalysts.