Synergistically tuned ionic liquid supported redox active cobalt oxide/PANI electrocatalyst for boosting molecular hydrogen evolution

Developing cost-effective, bifunctional electrocatalysts with high activity across a broad pH range is critical for scalable hydrogen production. Cobalt-based catalysts, while promising, are often limited by poor conductivity, interfacial resistance, and instability of active sites. Here, we report an in-situ engineered hybrid electrocatalyst comprising reduced graphene oxide (rGO), cobalt oxide (Co₃O₄), and polyaniline (PANI), synergistically doped with the ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIM TFSI). This ionic doping modulates interfacial proton transfer, enhances ion transport, and improves surface wettability, enhancing electrochemical stability and activity. The hybrid (r-Co₃O₄/P) exhibits low overpotentials of 158 mV and 176 mV at 10 mA cm⁻² in 0.1 M H₂SO₄ and 0.1 M KOH, respectively, with excellent durability over 10,000 cycles. It achieves turnover frequencies of 1.56 s⁻¹ (acidic) and 0.32 s⁻¹ (alkaline) at 100 mV overpotential, demonstrating strong intrinsic hydrogen evolution activity. These results establish ionic liquid-doped hybrid catalysts as viable bifunctional HER candidates for next-generation water electrolysis systems.