Hydrogenase Enzyme like Nanocatalysts FeS2 and FeSe2 for Molecular Hydrogen Evolution Reaction

Abstract Hydrogen generation through electrocatalytic water reduction using copious and scalable electrocatalyst is one of the potential method to produce clean energy. Transition metal dichalcogenides with appropriate band potential have been demonstrated as potential electrocatalysts for hydrogen evolution reaction (HER). Here in we have synthesized nanostructured FeS2 and FeSe2 that possess defined and irregular shaped flower like morphology using solvothermal reduction method. X-ray powder diffraction (XRD) confirms the pyrite FeS2 (iron disulfide) and orthorhombic phase FeSe2 (iron diselenide) and compared it’s HER catalytic performance. FeSe2 exhibited lower over potential of 113 mV with a current of 2 mA/cm2 (10 mA/cm2 current at 244 mV) compared to FeS2 with over potential 453 mV. The improved catalytic behavior of FeSe2 can be attributed to favourable bond strength between selenide and hydrogen (276 kJ/mol) which is about 87 kJ/mol lesser than FeS2 (363 kJ/mol).