Heterometallic molecular Ni-salen catalysts for efficient electrocatalytic oxygen evolution reaction

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• The electrochemical oxygen evolution reaction (OER) is crucial for energy conversion technologies like water splitting.
• Developing efficient and stable electrocatalysts for OER remains a significant challenge.
• Salen-based metal complexes offer tunable electronic and structural properties for catalytic applications.

Purpose of the Study:

• To synthesize and investigate novel salen-based heterometallic nickel (Ni) complexes as electrocatalysts for the OER.
• To elucidate the catalytic mechanism and identify key active species during the OER process.
• To evaluate the catalytic activity and long-term stability of the developed Ni complexes.

Main Methods:

• Synthesis of salen-based heterometallic Ni complexes.
• Electrochemical characterization using techniques such as cyclic voltammetry and chronoamperometry.
• In-situ electrochemical analysis to probe the active catalytic interface.
• Stability testing under OER conditions.

Main Results:

• Complex 4, a salen-based heterometallic Ni complex, exhibited significant OER activity, achieving 50 mA cm^-2 at a low overpotential of 350 mV.
• The catalytic process was found to follow the lattice oxygen mechanism (LOM).
• Complex 4 demonstrated excellent stability, maintaining its performance for 24 hours.
• Electrochemical analysis identified the formation of a 4/Ni(O)OH heterointerface, which serves as the active catalytic site.

Conclusions:

• Salen-based heterometallic Ni complexes are promising electrocatalysts for the oxygen evolution reaction.
• Complex 4 shows superior performance and stability, driven by the formation of a unique 4/Ni(O)OH heterointerface.
• The lattice oxygen mechanism (LOM) plays a key role in the OER catalyzed by these complexes, offering insights for future catalyst design.