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 (CoSexS2–x@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 CoSexS2–x (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.