Design of ligand mediated anisotropic Co3O4 nanorods for improved green hydrogen production electrochemically across different pH levels and substrates

Abstract

Designing an efficient electrocatalyst for the Hydrogen Evolution Reaction (HER) is the need of the hour to overcome the energy crisis. Herein, we report a simple solvothermal strategy to synthesize anisotropic Co₃O₄ nanorods by the controlled growth of nanoparticles. The reaction time was systematically varied from 12 to 24 h, in 6 h intervals to optimize the nanostructure and enhance HER performance. For the HER, we fabricated working electrodes with glassy carbon electrodes (GCEs) and Ni foam to deposit the synthesized nanostructures. The HER was performed in both acidic and alkaline electrolytes to thoroughly investigate the HER mechanism. Among the tested electrocatalysts, the nanorods obtained after 12 h of synthesis exhibited the best performance on Ni foam, requiring only 170 mV overpotential to drive 10 mA cm⁻² current density with the corresponding Tafel slope value of 98 mV dec⁻¹ in 1 M KOH. In contrast, 10 mA cm⁻² current density was achieved at 411 mV overpotential with a Tafel slope of 35 mV dec⁻¹, exhibiting faster kinetics on GCEs. These results surpass most of the previously reported data, making Co₃O₄ nanorods an efficient alternative to costly Pt.