Fe-Doped NiCo2Se4 Nanorod Arrays as Electrocatalysts for Overall Electrochemical Water Splitting

The development of efficient, affordable, and earth-abundant bifunctional electrocatalysts is vital for the water-splitting reaction. In this article, we have fabricated NiCo2Se4 and Fe-doped NiCo2Se4 through a simple hydrothermal route on the surface of carbon cloth with nanorod morphology. The developed electrocatalyst was thoroughly investigated by various techniques like PXRD, XPS, FESEM, ICP-AES, and TEM analysis. The optimized Fe0.2NiCo1.8Se4 has worked finest for hydrogen and oxygen evolution in an alkaline medium; it entails a potential of 148 mV and 1.656 V vs RHE to obtain 50 and 100 mA/cm2 current densities for HER and OER, respectively. The Tafel slope values for HER and OER are 85.7 and 56.3 mV/dec, respectively. This catalyst is stable under an alkaline medium for 48 h. The best HER and OER activity recommends the catalyst as a bifunctional in an alkaline medium, and the developed cell consisting of a doped sample requires 1.51 V to generate a 10 mA/cm2 current density with 24 h of stability. The Fe0.2NiCo1.8Se4 catalyst has a good Faradaic efficiency of 89.9% for overall water splitting. The nanorod morphology has a specific role in enhancing the electron transportation and conductivity of Fe0.2NiCo1.8Se4. The doping with Fe in NiCo2Se4 enhances the active sites and increases its electrocatalytic performance. The SCN- poisoning effect on metal ions in Fe0.2NiCo1.8Se4 suggests that Fe, Co, and Ni metals have a prominent impact on the overall electrocatalytic activity. Additionally, DFT investigation indicates that after Fe doping in a NiCo2Se4 zero band gap, minimum Gibbs free energy, maximum hydrogen, and oxygen coverage calculations are accountable for the higher conductivity of the system. This research provides a simple approach for synthesizing a Fe-doped ternary NiCo2Se4 nanorod array on the surface of carbon cloth, which is highly active and stable for water splitting in an alkaline medium.