Ultrasmall surface functionalized nanoclusters (Ni, Cu and Co) for high performance oxygen evolution catalysis

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• The oxygen evolution reaction (OER) is critical for water electrolysis but suffers from sluggish kinetics, hindering efficient hydrogen production.
• Nanoscale materials engineering offers enhanced surface area and tunable properties to accelerate the OER process.
• Developing cost-effective and efficient electrocatalysts is crucial for sustainable hydrogen energy.

Purpose of the Study:

• To synthesize and characterize thiol-stabilized transition metal ultrasmall nanoclusters (MNCs) as potential OER electrocatalysts.
• To investigate the size and surface chemistry control of MNCs for optimized catalytic activity.
• To evaluate the electrochemical performance of Ni, Co, and Cu MNCs for the oxygen evolution reaction.

Main Methods:

• Synthesis of transition metal nanoclusters (MNCs) using 1-dodecanethiol and 2-phenylethanethiol.
• Characterization using UV-visible, FT-IR, EDX, XPS, STEM, and HRTEM techniques.
• Electrochemical evaluation of OER activity, including onset potential, current density, Tafel slope, and mass activity.

Main Results:

• Successfully synthesized uniform MNCs (size ≤ 2 nm) with controlled size and surface chemistry.
• Nickel nanoclusters (NiNCs) exhibited excellent OER performance: low onset potential (~1.46 V vs. RHE), high current density (~125 mA cm⁻² at 1.7 V), and a low Tafel slope (99 mV dec⁻¹).
• NiNCs outperformed benchmark catalysts RuO₂ and IrO₂, showing superior activity, mass activity (~400 A g⁻¹ at 1.7 V), and stability.

Conclusions:

• Thiol-stabilized transition metal ultrasmall nanoclusters, particularly NiNCs, are highly effective electrocatalysts for the oxygen evolution reaction.
• The precise control over size and surface chemistry of MNCs is key to enhancing OER kinetics.
• These findings present a promising pathway for developing advanced, cost-effective electrocatalysts for sustainable hydrogen production via water electrolysis.