Hierarchical Ternary Carbon Nanocomposite on Stainless Steel for Low-Overpotential Hydrogen Evolution in Alkaline Water Electrolysis

Alkaline water electrolysis (AWE) is a promising technology for sustainable hydrogen production, though its efficiency is often limited by high overpotentials and the low electroactive surface area of conventional electrodes. In this study, a monolayer ternary carbon nanomaterial (CNM) composite electrode was fabricated on stainless steel current collectors using reduced graphene oxide (rGO), carbon nanotubes (CNT), and Vulcan carbon black (XC-72) as conductive carbon filler (CCF) with a hybrid PVA–PTFE binder. Thermal treatment was employed to partially decompose the PVA, creating a hierarchical porous structure that enhances electrolyte accessibility and electron transport. Electrochemical evaluations in 0.12 M NaOH, using a three-electrode system, showed significantly higher anodic peak currents for the modified electrode (approximately 5.1×10^-3 A) compared with bare stainless steel (5.0×10^-4 A) at 50 mV/s. Electrochemical impedance spectroscopy (EIS) indicated a reduced solution resistance (Rs) of 1.91–2.2 Ω.cm² and increased interfacial capacitance. The modified electrode achieved a peak current density (i₀) of 143.61 mA/cm² at 1.0 V, representing a 134% increase over the bare substrate. Furthermore, gas evolution tests produced 1.393 mL/min of oxyhydrogen (HHO) at 4.0 V, compared to 1.169 mL/min for the unmodified electrode, with stable operation observed over four hours of continuous testing. These results demonstrate that the synergistic combination of rGO, CNTs, and carbon black forms a conductive hierarchical network that effectively increases electroactive surface area, providing a cost-effective strategy for enhancing hydrogen evolution in alkaline water electrolysis.