Pyrolysis of a self-supported dodecyl sulfate anion-intercalated Co(OH)2 nanosheet with enlarged amorphous phase content towards enhanced activity for alkaline water oxidation

Highly active electrocatalysts made of earth-abundant elements are vital for efficient and cost-effective energy storage and conversion systems. In this communication, we report the further amorphization of a solvothermally synthesized dodecyl sulfate anion-intercalated cobalt hydroxide nanosheet array on nickel foam (DS-Co(OH)2/NF) via pyrolysis. Owing to the greatly enlarged interlayer distance of the DS-Co(OH)2/NF precursor (2.4 nm), and the more exposed active sites due to the enlarged amorphous phase content, the resulting P-DS-Co(OH)2/NF exhibits boosted activity as a 3D catalyst electrode for alkaline water oxidation. In 1.0 M KOH, an overpotential of only 266 mV is needed to drive a geometrical catalytic current density of 70 mA cm-2, which is 74 and 121 mV lower than the overpotentials for the DS-Co(OH)2/NF precursor and for Co(OH)2 without DS anion intercalation (Co(OH)2/NF), respectively. Impressively, this catalyst also displays superior long-term stability with a high turnover frequency value of 0.055 O2 s-1 at an overpotential of 340 mV.