Intramolecular Electron Transfer Governs Photoinduced Hydrogen Evolution by Nickel-Substituted Rubredoxin: Resolving Elementary Steps in Solar Fuel Generation

2019 ◽  
Vol 123 (46) ◽  
pp. 9792-9800 ◽  
Author(s):  
Sean C. Marguet ◽  
Michael J. Stevenson ◽  
Hannah S. Shafaat
Keyword(s):  
Electron Transfer ◽  
Hydrogen Evolution ◽  
Intramolecular Electron Transfer ◽  
Solar Fuel ◽  
Elementary Steps ◽  
Solar Fuel Generation

scholarly journals Nickel phlorin intermediate formed by proton-coupled electron transfer in hydrogen evolution mechanism

2015 ◽  
Vol 113 (3) ◽  
pp. 485-492 ◽  
Author(s):  
Brian H. Solis ◽  
Andrew G. Maher ◽  
Dilek K. Dogutan ◽  
Daniel G. Nocera ◽  
Sharon Hammes-Schiffer
Keyword(s):  
Electron Transfer ◽  
Proton Transfer ◽  
Hydrogen Evolution ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Strong Acid ◽  
Cyclic Voltammograms ◽  
Intramolecular Electron Transfer ◽  
Proton Coupled Electron Transfer ◽  
Proton Relay

The development of more effective energy conversion processes is critical for global energy sustainability. The design of molecular electrocatalysts for the hydrogen evolution reaction is an important component of these efforts. Proton-coupled electron transfer (PCET) reactions, in which electron transfer is coupled to proton transfer, play an important role in these processes and can be enhanced by incorporating proton relays into the molecular electrocatalysts. Herein nickel porphyrin electrocatalysts with and without an internal proton relay are investigated to elucidate the hydrogen evolution mechanisms and thereby enable the design of more effective catalysts. Density functional theory calculations indicate that electrochemical reduction leads to dearomatization of the porphyrin conjugated system, thereby favoring protonation at the meso carbon of the porphyrin ring to produce a phlorin intermediate. A key step in the proposed mechanisms is a thermodynamically favorable PCET reaction composed of intramolecular electron transfer from the nickel to the porphyrin and proton transfer from a carboxylic acid hanging group or an external acid to the meso carbon of the porphyrin. The C–H bond of the active phlorin acts similarly to the more traditional metal-hydride by reacting with acid to produce H2. Support for the theoretically predicted mechanism is provided by the agreement between simulated and experimental cyclic voltammograms in weak and strong acid and by the detection of a phlorin intermediate through spectroelectrochemical measurements. These results suggest that phlorin species have the potential to perform unique chemistry that could prove useful in designing more effective electrocatalysts.

scholarly journals Light Harvesting Proteins for Solar Fuel Generation in Bioengineered Photoelectrochemical Cells

2014 ◽  
Vol 15 (4) ◽  
pp. 374-384 ◽  
Author(s):  
Julian Ihssen ◽  
Artur Braun ◽  
Greta Faccio ◽  
Krisztina Gajda-Schrantz ◽  
Linda Thöny-Meyer
Keyword(s):  
Light Harvesting ◽  
Photoelectrochemical Cells ◽  
Solar Fuel ◽  
Solar Fuel Generation

Intramolecular Electron Transfer Mediated by a Tetrathiafulvalene Bridge in a Purely Organic Mixed-Valence System

2003 ◽  
Vol 42 (24) ◽  
pp. 2765-2768 ◽  
Author(s):  
Nicolas Gautier ◽  
Frédéric Dumur ◽  
Vega Lloveras ◽  
José Vidal-Gancedo ◽  
Jaume Veciana ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Mixed Valence ◽  
Intramolecular Electron Transfer

scholarly journals Solvent-induced on/off switching of intramolecular electron transfer in a cyanide-bridged trigonal bipyramidal complex

2016 ◽  
Vol 45 (43) ◽  
pp. 17104-17107 ◽  
Author(s):  
Rong-Jia Wei ◽  
Ryohei Nakahara ◽  
Jamie M. Cameron ◽  
Graham N. Newton ◽  
Takuya Shiga ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Spin Transition ◽  
Intramolecular Electron Transfer ◽  
Thermally Induced ◽  
Trigonal Bipyramidal ◽  
Transition Behaviour

A cyanide-bridged trigonal bipyramidal [Co3Fe2] cluster shows solvent-driven reversible on/off switching of its thermally induced electron-transfer-coupled spin transition behaviour.

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