FeCoSe₂ Nanoparticles Embedded in g-C₃N₄: A Highly Active and Stable bifunctional electrocatalyst for overall water...

To investigate cost affordable and robust HER and OER catalysts with significant low overpotentials, we have successfully embedded FeCoSe₂ spheres on smooth surfaces of graphitic carbon nitride that demonstrated high stability and electrocatalytic activity for H₂ production. We systematically analyzed the composition and morphology of Fe_xCo_1-xSe₂/g-C₃N₄ and attributed the remarkable electrochemical performance of the catalyst to its unique structure. Fe_0.2Co_0.8Se₂/g-C₃N₄ showed a superior HER activity, with quite low overpotential value (83 mV at -20 mA cm^-2 in 0.5 M H₂SO₄) and a current density of -3.24, -7.84, -14.80, -30.12 mA cm^-2 at 0 V (vs RHE) in Dulbecco's Phosphate-Buffered Saline (DPBS), artificial sea water (ASW), 0.5 M H₂SO₄ and 1 M KOH, respectively. To the best of our knowledge, these are the highest reported current densities at this low potential value, showing intrinsic catalytic activity of the synthesized material. Also, the catalyst was found to deliver a high and stable current density of -1000 mA cm^-2 at an overpotential of just 317 mV. Moreover, the synthesized catalyst delivered a constant current density of -30 mA cm^-2 for 24 h without any noticeable change in potential at -0.2 V. These attributes confer our synthesized catalyst to be used for renewable fuel production and applications.