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

## TL;DR

This study shows that adding molybdenum and boron to NiCo-based alloys improves their efficiency and stability for the oxygen evolution reaction, a key process in sustainable energy technologies.

## Contribution

The paper introduces a quaternary NiCoMoB alloy with an optimized Mo/B ratio and a surfactant-assisted synthesis method for enhanced OER performance.

## Key findings

- NiCoMoyBy with a 1:1 Mo/B ratio showed the best OER activity with an overpotential of 284 mV.
- NiCoMoyBy-SA nanoparticles achieved the lowest onset potential of 1.45 V and high stability over 10 days at 100 mA/cm2.
- The catalysts demonstrated minimal overpotential increase (0.02 mV/h) and retained activity under high current densities.

## Abstract

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.