Hybridized bimetallic Ni–Fe and Ni–Co spinels infused N-doped porous carbon as bifunctional electrocatalysts for efficient overall water splitting

Abstract

Water splitting is a potentially cost-effective and eco-friendly process to realize sustainable hydrogen fuel production. Though, the generation of hydrogen is limited by the kinetically sluggish and high overpotential of the OER and HER. The importance of producing highly efficient and inexpensive electrocatalysts to boost the competence of overall water splitting (OWS) cannot be overstated. In this regard, we produce NiFe3O4 and NiCo2O4 modified on nitrogen-doped porous carbon (N-PC) via hydrothermal and carbonization process to explore the synergy of hybridized bimetallic Ni–Fe, and Ni–Co spinels infused N-PC on selective catalytic active sites in OER and HER. The NiFe3O4@N-PC electrocatalyst exhibited remarkable bifunctional activity with the lowest overpotential of 0.23 V in OER and 0.21 V in HER at 10 mA/cm2 among the investigated catalysts. Notably, the N-PC with structural defects on the NiFe3O4 catalyst can boost the conductivity, enhance the larger surface area and contribute to the abundant active sites with electron transfer, facilitating the electrochemical HER and OER activity. Furthermore, the assembled water electrolyzer with a two-electrode configuration using NiFe3O4@N-PC can deliver a lower cell voltage of ∼1.6 V than the NiCo2O4@N-PC (∼1.65 V) to reach 10 mA cm−2 and the amount of gas and energy efficiency were calculated to be 0.003528 mol and 0.036699 g/kWh for NiFe3O4@N-PC. The exceptional performance of the bimetallic oxide@N-PC composite highlights not only potential as a non-noble electrocatalyst but also stipulates an originating catalytic function for advanced energy conversion electrocatalysts and beyond. © 2022 Hydrogen Energy Publications LLC