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Title: Charge separation related to photocatalytic H 2 production from a Ru–apoflavodoxin–Ni biohybrid

The direct creation of a fuel from sunlight and water via photochemical energy conversion provides a sustainable method for producing a clean source of energy. Here we report the preparation of a solar fuel biohybrid that embeds a nickel diphosphine hydrogen evolution catalyst into the cofactor binding pocket of the electron shuttle protein, flavodoxin (Fld). The system is made photocatalytic by linking a cysteine residue in Fld to a ruthenium photosensitizer. Importantly, the protein environment enables the otherwise insoluble Ni catalyst to perform photocatalysis in aqueous solution over a pH range of 3.5–12.0, with optimal turnover frequency 410 ± 30 h –1 and turnover number 620 ± 80 mol H 2/mol hybrid observed at pH 6.2. For the first time, a reversible light-induced charge-separated state involving a Ni(I) intermediate was directly monitored by electron paramagnetic resonance spectroscopy. As a result, transient optical measurements reflect two conformational states, with a Ni(I) state formed in ~1.6 or ~185 μs that persists for several milliseconds as a long-lived charge-separated state facilitated by the protein matrix.
Authors:
 [1] ; ORCiD logo [2] ;  [3] ;  [2] ;  [2] ; ORCiD logo [2]
  1. Argonne National Lab. (ANL), Argonne, IL (United States); Bridgewater State Univ., Bridgewater, MA (United States)
  2. Argonne National Lab. (ANL), Argonne, IL (United States)
  3. Argonne National Lab. (ANL), Argonne, IL (United States); The Univ. of Chicago, Chicago, IL (United States); Stanford Univ., Stanford, CA (United States)
Publication Date:
Grant/Contract Number:
AC02-06CH11357
Type:
Accepted Manuscript
Journal Name:
ACS Energy Letters
Additional Journal Information:
Journal Volume: 2; Journal Issue: 1; Journal ID: ISSN 2380-8195
Publisher:
American Chemical Society (ACS)
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 14 SOLAR ENERGY
OSTI Identifier:
1364651