Systematic Investigation of the Role of Molybdenum and Boron in NiCo-Based Alloys for the Oxygen Evolution Reaction

Quaternary NiCoMoB electrocatalysts exhibited significantly enhanced OER performance compared to their ternary NiCoMo and NiCoB counterparts. An optimal Mo/B ratio of 1 (NiCoMo_yB_y) 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. NiCoMo_yB_y-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 NiCoMo_xB_1-x, NiCoMo_yB_y, and NiCoMo_yB_y-SA exhibiting 293, 284, and 270 mV, respectively. NiCoMo_yB_y-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 NiCoMo_yB_y-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.