Ni-NiO Heterojunction: A Binder-Free Catalyst for Enhanced Oxygen Evolution Reaction

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Developing efficient electrocatalysts is crucial for energy conversion technologies like alkaline electrolysis.
• Nickel-based materials are promising but require optimization for enhanced activity and stability.

Purpose of the Study:

• To synthesize and characterize novel nanostructured nickel suboxides.
• To investigate the effect of annealing environments on material properties and electrocatalytic performance for the oxygen evolution reaction (OER).

Main Methods:

• Two-step electrochemical anodization to create porous nickel suboxides.
• Annealing in different atmospheres (air, Ar, Ar/H2).
• Characterization using XPS, FE-SEM, HR-TEM, and Mott-Schottky analysis.
• Electrochemical performance evaluation for OER.

Main Results:

• Annealing in Ar/H2 yielded a Ni-NiO heterojunction with high defect density.
• The Ni-NiO heterojunction exhibited significantly enhanced electrocatalytic activity for OER.
• Achieved a low overpotential (293 mV at 10 mA cm-2) and Tafel slope (74 mV dec-1).
• Demonstrated excellent stability over 1000 cycles, outperforming RuO2 by 1.72x.

Conclusions:

• Binder-free Ni-NiO heterojunctions are highly effective electrocatalysts for OER.
• Defect engineering and heterojunction formation are key strategies for improving catalyst performance.
• This work presents a promising pathway for developing advanced electrocatalysts for alkaline electrolysis.