A Keggin Polyoxometalate Shows Water Oxidation Activity at Neutral pH: POM@ZIF‐8, an Efficient and Robust Electrocatalyst

• Published in: Angewandte Chemie International Edition Vol. 57; no. 7; pp. 1918 - 1923
• Main Authors: Mukhopadhyay, Subhabrata, Debgupta, Joyashish, Singh, Chandani, Kar, Aranya, Das, Samar K.
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 12.02.2018
• Edition: International ed. in English
• Subjects: Anions; Catalysis; Chemical evolution; EGR-1 protein; electrocatalysis; Keggin polyoxometalates; Metal-organic frameworks; neutral pH; Oxidation; pH effects; Polyoxometallates; Void space; water oxidation; ZIF-8 MOF; ZIF-8 MOF; neutral pH; water oxidation; electrocatalysis; Keggin polyoxometalates
• ISSN: 1433-7851; 1521-3773; 1521-3773
• DOI: 10.1002/anie.201711920

Keggin‐type polyoxometalate anions [XM12O40]n− are versatile, as their applications in interdisciplinary areas show. The Keggin anion [CoW12O40]6− turns into an efficient and robust electrocatalyst upon its confinement in the well‐defined void space of ZIF‐8, a metal–organic framework (MOF). [H6CoW12O40]@ZIF‐8 is so stable to water oxidation that it retains its initial activity even after 1000 catalytic cycles. The catalyst has a turnover frequency (TOF) of 10.8 mol O2(mol Co)−1 s−1, one of the highest TOFs for electrocatalytic oxygen evolution at neutral pH. Controlled experiments rule out the chances of formation and participation of CoOx in this electrocatalyic water oxidation. Active upon encapsulation: An efficient (turnover frequency ca. 11 s−1) and robust electrochemical water oxidation catalyst was designed and synthesized by exploring host–guest chemistry between two catalytically inactive components, zeolitic imidazolate framework‐8 and a Keggin polyoxometalate anion. The encapsulated unsubstituted Keggin anion shows water oxidation activity at neutral pH.