Molecule Confined Isolated Metal Sites Enable the Electrocatalytic Synthesis of Hydrogen Peroxide.
basic_science · Level V
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- Record sourced from PubMed, PMID 34541729.
- Also identified by DOI 10.1002/adma.202104891.
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Abstract
The direct synthesis of hydrogen peroxide (H<sub>2</sub> O<sub>2</sub> ) through the two-electron oxygen reduction reaction is a promising alternative to the industrial anthraquinone oxidation process. Selectivity to H<sub>2</sub> O<sub>2</sub> is however limited by the four-electron pathway during oxygen reduction. Herein, it is reported that aminoanthraquinone confined isolated metal sites on carbon supports selectively steer oxygen reduction to H<sub>2</sub> O<sub>2</sub> through the two-electron pathway. Confining isolated NiN<sub>x</sub> sites under aminoanthraquinone increases the selectivity to H<sub>2</sub> O<sub>2</sub> from below 55% to above 80% over a wide potential range. Spectroscopy characterization and density functional theory calculations indicate that isolated NiN<sub>x</sub> sites are confined within a nanochannel formed between the molecule and the carbon support. The confinement reduces the thermodynamic barrier for OOH* desorption versus further dissociation, thus increasing the selectivity to H<sub>2</sub> O<sub>2</sub> . It is revealed how tailoring noncovalent interactions beyond the binding site can empower electrocatalysts for the direct synthesis of H<sub>2</sub> O<sub>2</sub> through oxygen reduction.