Polyhydroxyurethane/Cobalt Nanocomposites as Green Non-PGM Electrocatalysts for OER

Developing low-cost, efficient non-platinum group metal (non-PGM) electrocatalysts for the oxygen evolution reaction (OER) is critical for advancing green hydrogen production. In search of such a non-PGM catalyst, in this study, biodegradable polyhydroxyurethane (PHU) and cobalt salt nanocomposites were developed as green OER electrocatalysts for alkaline conditions (pH ∼13). Various amino acid-based PHUs were blended with cobalt salt and sodium alginate (NaAL), yielding non-PGM electrocatalysts (PHU1-PHU6). NaAL enhanced catalytic performance by improving ion and mass transport at the PHU-alginate interface. The hybrid catalysts exhibited superior OER activity, with PHU6 achieving a current density of 32 mA/cm² at 1.58 V, outperforming the benchmark RuO₂ (17 mA/cm² at 1.45 V) and CoO_x (12 mA/cm² at 1.53 V). PHU6 also demonstrated a lower Tafel slope (102 mV/dec), higher electrochemical surface area (53 cm²), double-layer capacitance (1.32 mF), and similar overpotential (239 mV @ 10 mA/cm²) compared to RuO₂ and CoO_x. Its Faradic efficiency (∼80%) surpassed RuO₂ (76%) and CoO_x (73%). The structure of PHUs significantly influenced these electrochemical parameters, showcasing PHU6's promise as a cost-effective, sustainable OER catalyst with excellent performance and stability.