CeO_x-Induced Spatial and Electronic Modulation for General Direct Oxo Coupling in Transition Metal Hydroxides

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Electrochemical water splitting is key for sustainable hydrogen generation.
• The oxygen evolution reaction (OER) kinetics are a major bottleneck, often limited by transition metal catalysts.
• Optimizing OER requires strategies to enhance catalytic activity and stability.

Purpose of the Study:

• To develop a novel catalyst for accelerating the oxygen evolution reaction (OER) in electrochemical water splitting.
• To investigate the synergistic effects of anchoring CeOₓ nanoparticles onto Ni(OH)₂ nanosheets for dual spatial and electronic modulation.
• To demonstrate the potential of this strategy for efficient and stable hydrogen production.

Main Methods:

• Synthesis of CeOₓ nanoparticles anchored onto two-dimensional Ni(OH)₂ nanosheets.
• Characterization of the catalyst's structure, morphology, and electronic properties.
• Electrochemical testing of the catalyst for OER performance in alkaline media.
• Integration of the catalyst into an alkaline anion exchange membrane water electrolyzer (AEMWE).

Main Results:

• The CeOₓ@Ni(OH)₂ catalyst achieved a low overpotential of 152 mV at 10 mA cm⁻², significantly enhancing OER kinetics.
• The catalyst demonstrated excellent long-term stability, operating continuously for over 2000 hours with minimal performance decay.
• In an alkaline anion exchange membrane water electrolyzer (AEMWE), the catalyst required 1.91 V to reach 1 A cm⁻² and operated stably for 450 hours.
• The synergistic effect shifted the OER mechanism to the oxide pathway mechanism (OPM), improving catalytic efficiency.

Conclusions:

• Anchoring CeOₓ nanoparticles onto Ni(OH)₂ nanosheets effectively modulates spatial and electronic properties, accelerating OER kinetics.
• The CeOₓ@Ni(OH)₂ catalyst exhibits superior performance and stability for electrochemical water splitting.
• The OPM activation strategy is broadly applicable to other transition metal hydroxides, offering a promising route for enhancing alkaline OER.