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

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 H-2 production. We systematically analyzed the composition and morphology of FexCo1-xSe2/g-C3N4 and attributed the remarkable electrochemical performance of the catalyst to its unique structure. Fe0.2Co0.8Se2/g-C3N4 showed a superior HER activity, with quite low overpotential value (83mV at -20 mA cm(-2) in 0.5M H2SO4) and a current density of -3.24, -7.84, -14.80, -30.12mAcm(-2) at 0V (vs RHE) in Dulbecco's Phosphate-Buffered Saline (DPBS), artificial sea water (ASW), 0.5M H2SO4 and 1M 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 317mV. Moreover, the synthesized catalyst delivered a constant current density of -30 mA cm(-2) for 24h without any noticeable change in potential at -0.2V. These attributes confer our synthesized catalyst to be used for renewable fuel production and applications.