Electrocatalytic oxygen evolution from water on a Mn(III-V) dimer model catalyst--a DFT perspective.

Area of Science:

• Computational Chemistry
• Catalysis
• Biomimetic Chemistry

Background:

• Water oxidation and oxygen evolution reaction (OER) are crucial for artificial photosynthesis and renewable energy.
• Understanding the OER mechanism at the molecular level is essential for designing efficient catalysts.

Purpose of the Study:

• To computationally monitor a complete water oxidation and oxygen evolution reaction (OER) cycle.
• To investigate a biomimetic model catalyst for OER.
• To elucidate the mechanism of O-O bond formation and O2 evolution.

Main Methods:

• Density Functional Theory (DFT) calculations were employed to model the OER cycle.
• A biomimetic model catalyst featuring a μ-OH bridged Mn(III-V) dimer was utilized.
• The reaction mechanism was divided into electrochemical and chemical steps, with a focus on electron and proton transfer.

Main Results:

• The study identified unstable Mn(V)=O/Mn(IV)-O˙ intermediates that form a μ-peroxy O-O bond.
• A Zener
• spintronic
• type mechanism was proposed for virtually barrierless O2 evolution.
• DFT was extended to estimate the activation barrier for O-O bond formation, addressing limitations in transition state calculations.

Conclusions:

• The biomimetic Mn dimer catalyst effectively facilitates the OER cycle.
• The proposed spintronic mechanism offers a pathway for highly efficient oxygen evolution.
• DFT is a valuable tool for studying OER mechanisms, with methods adapted to handle rate-limiting steps.