FeNi (oxy)hydroxides embedded with high-valence Mo atoms: A efficient and robust water oxidation electrocatalyst

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Oxygen evolution reaction (OER) is crucial for water splitting but hindered by high thermodynamic barriers.
• Transition metal (oxy)hydroxides are promising OER electrocatalysts, but their intrinsic activity needs improvement.
• Modulating electronic states via doping is a key strategy to enhance OER performance.

Purpose of the Study:

• To develop a novel electrocatalyst for efficient alkaline oxygen evolution reaction (OER).
• To investigate the effect of high-valence molybdenum doping on FeNi (oxy)hydroxides.
• To explore a self-reconstruction strategy for synthesizing advanced electrocatalysts.

Main Methods:

• Synthesis of MoFeNi (oxy)hydroxides using a self-reconstruction strategy with MoNiB as a sacrificial template.
• Electrocatalytic performance testing for OER in alkaline media.
• Characterization using various techniques and theoretical calculations to understand catalytic mechanisms.

Main Results:

• MoFeNi (oxy)hydroxides exhibited excellent OER activity with low overpotentials (η100 = 252 mV, η500 = 288 mV) and a small Tafel slope (18.35 mV dec⁻¹).
• The catalyst demonstrated robust stability, operating continuously at 500 mA cm⁻² for extended periods.
• Theoretical calculations confirmed that high-valence Mo doping optimized electronic structures and intermediate adsorption/desorption energies.

Conclusions:

• High-valence molybdenum doping is an effective strategy to enhance the intrinsic activity of FeNi (oxy)hydroxides for OER.
• The self-reconstruction synthesis route provides a novel approach for creating advanced electrocatalysts.
• The developed MoFeNi electrocatalyst shows great potential for applications in anion exchange membrane (AEM) electrolyzers.