Self-Template Synthesis of Co–Se–S–O Hierarchical Nanotubes as Efficient Electrocatalysts for Oxygen Evolution under Alkaline and Neutral Conditions

We develop a facile self-template synthetic method to construct hierarchical Co–Se–S–O (CoSe_<i>x</i>S_2–<i>x</i>@Co­(OH)₂) nanotubes on a carbon cloth as a self-standing electrode for electrocatalytic oxygen evolution reaction (OER). In the synthetic process, separate selenization and sulfurization on the Co­(OH)F precursor in different solvents have played an important role in constructing CoSe_<i>x</i>S_2–<i>x</i> (Co–Se–S) hierarchical nanotubes, which was further transformed into the nanotube-like Co–Se–S–O via an in situ electrochemical oxidation process. The Co–Se–S–O obtained by the Kirkendall effect through two stepwise anion-exchange reactions represents the first quaternary Co–Se–S–O nanotube array, which dramatically enhances its surface area and conductivity. Further, it only requires low overpotentials of 230 and 480 mV to achieve a 10 mA cm^–2 current density. The OER performance of Co–Se–S–O is much more efficient than that of its monochalcogenide counterparts, as well as the commercial benchmark catalyst IrO₂