Expediting Oxygen Evolution by Optimizing Cation and Anion Complexity in Electrocatalysts Based on Metal Phosphorous...

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Optimizing the rate-determining step (RDS) of the oxygen evolution reaction (OER) is crucial for efficient electrochemical water splitting.
• Current challenges lie in precisely controlling the RDS to enhance energy efficiency.

Purpose of the Study:

• To demonstrate that OER RDS can be regulated by varying cation and anion complexity in metal phosphorous trichalcogenide (MPT3) electrocatalysts.
• To achieve high OER activity and provide a predictive model for catalyst performance.

Main Methods:

• Synthesis and electrochemical testing of a family of MPT3 electrocatalysts (M=Fe, Ni; T=S, Se).
• Density functional theory (DFT) calculations to determine OER activity descriptor (ΔG(O*)–ΔG(OH*)).
• Development of a cation/anion complexity index to correlate with catalyst performance.

Main Results:

• Identified (Ni,Fe)P(S,Se)3 as a highly active OER electrocatalyst with an ultra-low Tafel slope (34 mV dec⁻¹).
• DFT calculations confirmed an optimal OER activity descriptor (1.5 eV) for the catalyst.
• Established a direct proportionality between the OER activity descriptor and the proposed cation/anion complexity index.

Conclusions:

• The cation and anion complexity in MPT3 electrocatalysts effectively regulate the OER RDS.
• Cation-anion interactions play a pivotal role in determining catalyst performance.
• The cation/anion complexity index offers a simple yet effective method for predicting OER catalytic activity.