Tunning the Nanoporous Structure of Cobalt-Iron-Based Nanocomposite via Doping Sulfur and Phosphorus for Charge Storage Application

Running a vehicle needs energy that is derived using fossil fuels mainly (gasoline) leads to the production of greenhouse gases like CO_2, which is the one of the main cause of global warming. So scientists worldwide are looking for clean and sustainable energy for which energy storage devices (ESDs) might be the one solution as they are the past, present, and the future of electric vehicles; without ESDs, these vehicles are not imaginable, providing significant support to the importance of ESDs. Apart from electric vehicles, ESDs have many applications in running electrical and electronic gadgets. The various types of ESDs are batteries, supercapacitor (SC), and fuel cells. Among these fuel cells are the clean and green energy sources, which use hydrogen (H₂) as a fuel. These fuel cells run on the basic principle of water (H₂O) splitting technology. Generally, rare earth metals like Platinum (Pt), Ruthenium (Ru), etc., are used as the electrocatalyst, among which Pt has the lowest possible overpotential ~ 42 mV, but these rare earth metals are expensive. Therefore, researchers worldwide are looking toward the transition metal-based composite. These composites play a vital role in green energy production. This work introduces the use of cobalt-iron (Co-Fe) based composite, which is further followed by the doping sulfur (S) and phosphorus (P) as highly efficient electrocatalyst. The electrocatalyst were synthesized using two facile synthesis routes in which they produce different morphology (nanoflowers and macroparticles). Nanoflowers are produced using the Co and Fe-based precursors via a solvothermal for a week at room temperature. While the macroparticle composite is prepared using a simple co-precipitation method. Their unique structure allows them to have more electroactive sites. Among nanoflowers, the best sample of P-Co-Fe showed an oxygen evolution overpotential of 340 mV at 10 mA/cm² with a Tafel slope of 48 mV/dec along with the hydrogen evolution overpotential of 46 mV to deliver 10 mA/cm². On the other hand, the macroparticle’s best sample of P-Co-Fe shows the oxygen evolution overpotential of 330 mV at 10 mA/cm² with a Tafel slope of 63 mV/dec along with the hydrogen evolution overpotential of 61 mV to reach 10 mA/cm². The stability of the prepared electrocatalysts was tested using cyclic linear voltammetry and chronoamperometry. Both the measurements showed high electrocatalytic stability of the prepared samples for over 1,000 cycles of linear voltammetry and 24 hrs of chronoamperometry test. Our research provides a cost-effective and highly efficient electrocatalyst for green energy production.