Trends of earth‐abundant transition metal‐doped in CoSe 2 microstructures towards improved water splitting and supercapacitor applications

Abstract

Rising high-tech innovations have brought forth alternative energy demands that in turn provide significant fillip to dig for advanced energy storage as well as conversion technologies. An efficient, low-cost, noble metal-free bifunctional catalyst for water dissociation and high energy density supercapacitor electrode can be a promising solution for a sustainably greener future. Herein, we have demonstrated a convenient strategy of defect engineering by transition metal doping for cultivating efficient active sites. The work features a highly stable (90.56% capacitance retention and ~97.86% of coulombic efficiency after 5000 cycles) asymmetric Fe doped CoSe2//titanium carbide (MXene) device with an energy density of 28.78 Wh/Kg at a power density of 778.6 W/Kg at a potential window of 1.5 V. Electrochemical kinetic analysis for the best-performing iron-doped cobalt selenide catalyst exposed an overpotential (ɳ10) of 157 mV (Tafel slope of 112 mV/dec) and 261 mV(Tafel slope of 57 mV/dec) for hydrogen and oxygen evolution respectively. Further, the structural and electronic properties were computed using first-principle calculations to address the modifications in electronic structures. Metal doping engineers density of states near Fermi level due to charge transfer from metal to the parent CoSe2, further the carrier density synergistically contributes towards the enhancement in quantum capacitance, overpotential for HER and OER thereby tuning the physicochemical properties.