Low-cost transition metals (Fe, Ni, Co) on carbon aerogel for water electrolysis and supercapacitor applications

Abstract

Cost-effective transition metals (TM = Fe, Ni, Co) were immobilized on carbon aerogel (CA) using microwave irradiation, followed by nitrogen doping into one catalyst series through heat treatment. The physical characterization of the synthesized catalysts included N<inf>2</inf> sorption, inductively coupled plasma-mass spectrometry, X-ray diffraction analysis, transmission electron microscopy, Raman spectroscopy, FTIR spectroscopy, and X-ray photoelectron spectroscopy. Co/CA displayed the best performance for oxygen evolution reaction (OER) electrocatalysis in alkaline water electrolysis, followed by Ni/CA. Co/CA exhibited a small Tafel slope of 110 mV dec⁻¹ and required an overpotential of just 276 mV to reach 10 mA cm⁻², lower than that of the commercial IrO<inf>2</inf> electrocatalyst. Additionally, Co/CA and Ni/CA demonstrated excellent long-term stability during OER, with activity increasing over time. Capacitance measurements also showed the potential of TM/CA materials as supercapacitor electrodes. Fe/CA achieved the highest performance, with a specific capacitance of 322 F g^-1 at a moderate current of 1 A g^-1. It retained up to 96 % of its capacitance over 1000 cycles, indicating excellent stability.