MOF-Derived Hierarchical CoSe₂ with Sheetlike Nanoarchitectures as an Efficient Bifunctional Electrocatalyst

The exploitation of efficient and stable non-noble-metal bifunctional electrocatalysts is key to the development of hydrogen production technology. Although some progress has been made in the synthesis of transition-metal selenide nanostructures, the preparation of metal-organic framework (MOF)-derived transition-metal selenide electrode materials with more active sites and nanosheet structures remains a significant challenge. Herein, on the basis of the MOFs, the hierarchical CoSe₂-160 microcube with sheetlike nanoarchitectures was successfully prepared. In addition, the morphology of cobalt selenides was controlled by adjusting the hydrothermal reaction temperature. Electrochemical experiments show that the CoSe₂-160 microcube has a splendid electrocatalytic performance with 10 mA cm^-2 at an overpotential of 156 mV and a small Tafel slope of 40 mV dec^-1 (in 0.5 M H₂SO₄) for hydrogen evolution reaction as well as 328 mV and a small Tafel slope of 73 mV dec^-1 (in 1 M KOH) for oxygen evolution reaction, respectively. This arises from the nanosheet structures, large surface areas, and abundant active sites. This strategy provides a neoteric synthesis route for the MOF-derived transition-metal selenides with a striking electrocatalytic performance.