Designing high-performance Pt-based catalysts for energy-efficient hydrogen production via ethanol electrolysis in acidic PEM environments

Ethanol electrolysis reactions (EER) offer a sustainable alternative to conventional water electrolysis for hydrogen production. This study systematically evaluates Pt-based catalysts incorporating transition metals (Cu, Ni, Au, Co, Ir, In, Sm, Ag, Pd, Ru, Rh) into binary, ternary, quaternary, and quinary systems for EER. Catalysts were prepared via a NaBH₄ reduction method at ambient temperature and characterized using XRD, TEM, and SEM. Among binary catalysts, PtCu/C exhibited superior activity at low potentials, while PtCo/C achieved higher current density at high potentials. The ternary PtCuAu/C catalyst outperformed all catalysts in aqueous electrolyte, demonstrating the lowest onset (0.23 V) and peak (0.71 V) potentials, alongside the highest current density (0.91 mA/cm²). Additionally, chronoamperometry revealed that PtCuAu/C retained 92% of its initial activity after 3500 s at 0.5 V, confirming long-term stability. Notably, PtCuAu/C maintained 81% CO₂ selectivity and sustained stability in a proton exchange membrane electrolysis cell (PEMEC) at 80 °C, revealing its activity for practical hydrogen production. The enhanced CO tolerance of PtCuAu/C is attributed to synergistic interactions between Cu (promoting C–C bond cleavage) and Au (weakening CO adsorption). Durability was further confirmed via chronoamperometry and electrochemical impedance spectroscopy in aqueous electrolyte, showing minimal resistance degradation. These findings highlight PtCuAu/C as a promising candidate for scalable and energy-efficient green hydrogen production, guiding future multi-metallic catalyst design.