Stoichiometry design in hierarchical CoNiFe phosphide for highly efficient water oxidation

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Rational design of trimetallic phosphide catalysts is crucial for improving surface reactions and catalytic efficiency.
• Developing advanced electrocatalysts is essential for energy conversion technologies like the oxygen evolution reaction (OER).

Purpose of the Study:

• To synthesize and optimize hierarchical CoNiFeP catalysts with controlled stoichiometry for enhanced OER performance.
• To investigate the catalytic mechanism and stability of the optimized trimetallic phosphide catalyst.

Main Methods:

• Synthesis of hierarchical CoNiFeP catalysts with precise stoichiometric control (x:y:z = (1-10):(1-10):1).
• Electrochemical evaluation of catalytic activity and long-term stability for the oxygen evolution reaction (OER).
• Density Functional Theory (DFT) calculations to understand the electronic structure changes and adsorption properties.

Main Results:

• The optimal composition, Co1.3Ni0.5Fe0.2P, exhibited remarkable catalytic activity (η = 320 mV at 10 mA cm⁻²) and stability (negligible decrease after 10 h).
• Surface phosphorus in Co1.3Ni0.5Fe0.2P was observed to be replaced by oxygen during the OER process.
• DFT calculations revealed increased density of states near the Fermi level for Co1.3Ni0.5Fe0.2P/Co1.3Ni0.5Fe0.2O, enhancing OH⁻ adsorption.

Conclusions:

• The optimized CoNiFeP catalyst demonstrates significant potential for efficient oxygen evolution reactions.
• Surface modification and electronic structure changes play a key role in the enhanced catalytic performance and stability.