Facile construction of hierarchical Co3S4/CeO2 heterogeneous nanorod array on cobalt foam for electrocatalytic overall water splitting.

[Display omitted] • Self-supported hierarchical Co 3 S 4 /CeO 2 nanorod array is fabricated via a facile one-step hydrothermal method. • Hierarchical heterostructured Co 3 S 4 /CeO 2 acts as efficient catalyst for overall water splitting, demonstrating superior activity and stability. • The introduction of CeO 2 greatly enhances the OER catalytical activity of Co 3 S 4 as illustrated by DFT calculation. Herein, a hierarchical Co 3 S 4 / CeO 2 nanorod array on cobalt foam (Co 3 S 4 / CeO 2 -CF) was successfully constructed via a facile one-step hydrothermal method. The fabrication of Co 3 S 4 / CeO 2 -CF was confirmed by X-ray diffraction, scanning electron microscope (SEM), high resolution transmission electron microscope (HRTEM). It is observed that CeO 2 nanorod was fully covered with Co 3 S 4 nanosheets, forming a hierarchical core–shell nanostructure. Furthermore, CeO 2 and Co 3 S 4 were doped with each other during the one-step hydrothermal process, forming a heterogeneous Co 3 S 4 / CeO 2 nanostructure. Density functional theory (DFT) calculations suggest that the introduction of CeO 2 in Co 3 S 4 is effective in reducing the free energy barrier of OER process. To achieve current density of 10 mA cm−2, only small overpotentials of 74.9 mV and 213 mV are required for HER and OER in 1.0 M KOH solution, respectively. In particular, the Co 3 S 4 / CeO 2 -CF based electrolysis cell for overall water splitting only needs an output voltage of 1.64 V in the alkaline medium, lower than that of Pt/C–RuO 2 -based electrolysis cells (1.70 V). Such hierarchical heterogeneous catalyst also shows ultra-stable catalytic activity. Therefore, with the favorable heterointerfaces and hierarchical structures, Co 3 S 4 / CeO 2 -CF could be a promising bifunctional electrocatalyst for overall water splitting and this study may also provide a facile method for the preparation of hierarchical heterogeneous nanostructured materials. [ABSTRACT FROM AUTHOR]