Tunable e_g Orbital Occupancy in Heusler Compounds for Oxygen Evolution Reaction*

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Heusler compounds offer tunable electronic structures and robust properties, making them attractive for catalysis.
• Electrocatalysis, particularly the oxygen evolution reaction (OER), is crucial for energy conversion technologies.

Purpose of the Study:

• To investigate the potential of Co₂ YZ-type Heusler compounds as electrocatalysts for the oxygen evolution reaction (OER).
• To establish a correlation between the electronic structure (e_g orbital filling) of cobalt sites and OER activity.

Main Methods:

• Synthesis of various Co₂ YZ Heusler crystals using the arc-melting method.
• Systematic variation of Y and Z elements to precisely control the e_g orbital filling of cobalt.
• Electrocatalytic testing for the oxygen evolution reaction (OER).

Main Results:

• A direct correlation was identified between e_g orbital filling approaching unity and higher OER catalytic current in Co₂ MnZ compounds (Z=Ti, Al, V, Ga).
• This trend was also observed in other Heusler compounds like Co₂ VZ (Z=Sn, Ga).
• Demonstrated proof of concept for Heusler compounds as a novel class of OER electrocatalysts.

Conclusions:

• Heusler compounds are a viable new class of electrocatalysts for the oxygen evolution reaction.
• Manipulation of spin orbitals, specifically e_g orbital filling, significantly influences the catalytic performance of these materials.