Operando High-Valence Cr-Modified NiFe Hydroxides for Water Oxidation

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• High-valence metal-doped multimetal (oxy)hydroxides show promise for oxygen evolution reaction (OER) catalysis, surpassing noble metals.
• Rational design of dopants to modulate electronic properties remains a challenge.

Purpose of the Study:

• To introduce operando high-valence dopants into multimetal layered double hydroxides (LDHs) for OER catalysis.
• To investigate the electronic interactions and catalytic performance of these doped LDHs.

Main Methods:

• Density functional theory (DFT) simulations were employed to guide catalyst design.
• Ultrathin Cr-doped NiFe LDH (NiFeCr-LDH) was synthesized and characterized using X-ray absorption spectroscopy.
• Electrocatalytic performance for OER was evaluated, and applications in water splitting and CO2 electrolysis were demonstrated.

Main Results:

• Cr doping in NiFe LDH facilitated strong electronic interactions between Cr dopants and NiFe sites.
• NiFeCr-LDH exhibited ultralow OER overpotentials (189 mV at 10 mA cm⁻² and 284 mV at 1000 mA cm⁻²).
• The NiFeCr-LDH anode demonstrated efficient alkaline water splitting and CO2-to-CO electrolysis with low cell voltages.

Conclusions:

• High-valence metal doping, specifically Cr in NiFe LDH, effectively modulates electronic structures for enhanced OER catalysis.
• NiFeCr-LDH serves as a robust electrocatalyst for energy conversion applications like water splitting and CO2 reduction.