Observation of O–O Bond Forming Step of Molecular Co₄O₄ Cubane Catalyst for Water Oxidation by Rapid-Scan FT-IR Spectroscopy

Journal Article · Mon Jan 13 00:00:00 EST 2020 · ACS Catalysis

DOI:https://doi.org/10.1021/acscatal.9b03281· OSTI ID:1582635

Liu, Hongfei ^[1]; Frei, Heinz  ^[1]

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1. Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

Monitoring of water oxidation by the established Co cubane catalyst Co₄O₄(OAc)₄(py)₄ (abbrev. Co₄O₄, OAc = acetate, py = pyridine) by time-resolved rapid-scan ATR FT-IR spectroscopy revealed the O–O bond forming intermediate by its O–O stretch mode at 833 cm^–1. The catalysis was either driven in alkaline solution by a visible light sensitizer or in hydroxide (OH^–) containing acetonitrile solution using the one-electron oxidized cubane as the sole source of charge. Finally, the μ-peroxido structure of the intermediate was established by ¹⁸O isotopic labeling, and its catalytic relevancy and role in the O₂ evolving cycle were revealed by the kinetic relationship with decreasing cubium ([Co₄O₄]⁺) and recovery of the Co₄O₄ complex.

• Research Organization: Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES); Swiss National Science Foundation (SNSF)
• Grant/Contract Number: AC02-05CH11231; P2ZHP2_168445
• OSTI ID: 1582635
• Journal Information: ACS Catalysis, Vol. 10, Issue 3; ISSN 2155-5435
• Publisher: American Chemical Society (ACS)
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
water oxidation catalysis
cobalt oxide
cubane
time-resolved FT-IR
peroxo intermediate
O-O bond formation