A Linear Mn₃ Molecular Cluster as a Bifunctional Electrocatalyst for Overall Water Splitting

Area of Science:

• Inorganic Chemistry
• Materials Science
• Electrochemistry

Background:

• Developing efficient molecular electrocatalysts is crucial for sustainable energy technologies.
• Manganese-based clusters offer potential due to their earth-abundant nature and tunable electronic properties.
• Linear multinuclear metal complexes are of interest for catalytic applications.

Purpose of the Study:

• To synthesize and characterize a novel manganese cluster with a linear MnII···MnII···MnII motif.
• To evaluate the electrocatalytic activity of the synthesized cluster for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER).
• To elucidate the reaction mechanisms using computational studies.

Main Methods:

• Synthesis of the manganese cluster [Mn3L2(μ2-OAc)2] (1) using H2L and Mn(OAc)2·4H2O.
• Characterization techniques including FTIR, UV-vis, FESEM, TGA, PXRD, and SCXRD.
• Electrochemical measurements for OER and HER activity, including overpotential determination.
• Density Functional Theory (DFT) calculations for mechanistic insights.

Main Results:

• The cluster [Mn3L2(μ2-OAc)2] (1) was successfully synthesized and structurally characterized, revealing a linear MnII···MnII···MnII arrangement.
• Compound 1 exhibited outstanding electrocatalytic activity for OER (324 mV) and HER (130 mV) at 10 mA/cm².
• DFT studies indicated the MnII-Ophenoxide-MnII linkage as the active site for both OER and HER.

Conclusions:

• The synthesized manganese cluster [Mn3L2(μ2-OAc)2] (1) is a highly effective molecular electrocatalyst for both OER and HER.
• The flexible organic ligand H2L facilitates the formation of the desired linear cluster structure.
• The MnII-Ophenoxide-MnII bridge plays a critical role in the catalytic mechanisms, paving the way for designing advanced electrocatalysts.