Metal-organic framework (MOF) derived flower-shaped CoSe2 nanoplates as a superior bifunctional electrocatalyst for both oxygen and hydrogen evolution reactions

The development of a non-precious metal-based stable and cost-effective bifunctional electrocatalyst remains a significant challenge for the production of hydrogen (H-2) and oxygen (O-2) through water splitting. Although some progress has been made to develop efficient electrocatalysts from transition metal-based nanostructured selenides, the electrocatalyst derived from metal-organic framework (MOF) transition metal selenides demands additional effort due to their well-defined morphological structure and high accessible surface area resulting in better electrochemical performances. Herein, by tuning the selenylation technique through a facile solvothermal approach, we have successfully synthesized flower-like CoSe2 nanoplates termed MOF-D CoSe2, derived from a Co-MOF of the formula [Co-3(tiron-bpy)(2)(bpy)(H2O)(8)]center dot(H2O)(2) [tiron = 4,5-dihydroxy-1,3-benzenedisulfonate disodium salt, and bpy = 4,4 '-bipyridyl]. The MOF-D CoSe2 performs as an excellent bifunctional electrocatalyst, which requires an overpotential of 320 mV to achieve the predefined current density of 10 mA cm(-2), with a Tafel slope of 60 mV dec(-1) in 1 M KOH to catalyze the oxygen evolution reaction (OER). For the hydrogen evolution reaction (HER), MOF-D CoSe2 needs an overpotential of 195 mV at 10 mA cm(-2) and a low Tafel slope of 43 mV dec(-1) in an acidic medium of 0.5 M H2SO4. The enhanced bifunctional electrochemical performance of the MOF-D CoSe2 electrocatalyst has been attributed to the combination of a unique flower-shaped morphology with a plate-like nanoarchitecture, higher electrochemical active surface area and robust stability in both acidic as well as alkaline media.

Automated summary

The development of a stable and cost-effective non-precious metal bifunctional electrocatalyst for hydrogen and oxygen production through water splitting remains a challenge. However, by tuning the selenylation technique, researchers have successfully synthesized a high-performance MOF-D CoSe2 electrocatalyst, showing excellent efficiency for oxygen and hydrogen evolution reactions in both alkaline and acidic media.