Quaternary NiCoMoB electrocatalysts exhibited significantly enhanced OER performance compared to their ternary NiCoMo and NiCoB counterparts. An optimal Mo/B ratio of 1 (NiCoMoyBy) demonstrated a superior OER activity, attributed to a balance between the electronic and structural contributions from Mo and B, maximizing the electrocatalytic site density and activity. NiCoMoyBy-SA, a nanoparticle version synthesized via a surfactant-assisted method, showed further improved performance. The OER activity was evaluated by comparing overpotentials at 10 mA/cm2, with NiCoMoxB1-x, NiCoMoyBy, and NiCoMoyBy-SA exhibiting 293, 284, and 270 mV, respectively. NiCoMoyBy-SA also demonstrated the lowest onset potential (1.45 V), reflecting a superior efficiency. Chronoamperometry in 1 M pre-electrolyzed KOH at 30 °C highlighted NiCoMoyBy-SA's stability, activating within hours at 10 mA/cm2 and stabilizing over 7 days. At 50 mA/cm2, the overpotential increased minimally (0.02 mV/h over 2 days), and even at 100 mA/cm2 for 10 days, the activity declined only slightly, affirming a high stability. These findings demonstrate NiCoMoB electrocatalysts as cost-effective, efficient OER electrocatalysts, advancing sustainable energy technologies.
Keywords: boron; cryo-milling; electrocatalyst; high-energy surfactant-assisted ball milling (HE-SABM); mechanical alloying; oxygen evolution reaction (OER); stability.