Iron nanoparticle engineered N-doped graphitic carbon composite as a binary electrocatalyst for overall water splitting and supercapacitor

Abstract

In this study, we report on the tailored synthesis of nitrogen-(N)-doped carbon and iron-(Fe)-loaded N-doped carbon composites and their use for the oxygen evolution reaction (OER), hydrogen evolution reaction (HER), overall electrochemical water splitting, and supercapacitors. FE-SEM and HR-TEM analyses reveal that the developed composite material exhibits a core-shell structure with enhanced porosity upon Fe incorporation. By adjusting the ratio of Fe to N-doped carbon in the composites, it was identified that the catalyst 5Fe@NC demonstrates outstanding electrochemical activity alongside commendable stability. Specifically, the 5Fe@NC electrocatalyst achieves current densities of +10 mAcm−2 and -10 mAcm−2 in alkaline electrolyte with minimal overpotentials of 376 mV and 520 mV, respectively. Notably, impressive Tafel slopes of 84 mV/dec and 212 mV/dec for the OER and HER were obtained, indicating superior kinetic activity of the developed composite materials. As a supercapacitor, 5Fe@NC electrode material exhibits a measurable specific capacitance of 294 F/g at 0.5 A/g current density with excellent durability (78 % retention after 1000 charge-discharge cycles). Furthermore, we conducted assessments on stability, charge transfer resistance, and ECSA, yielding excellent outcomes. This work successfully demonstrates a highly effective dual-purpose electrocatalyst prepared from indole and furfural (heterocycles abundant in biomass), exhibiting excellent electrochemical activity and stability in facilitating HER and OER within alkaline electrolytes.