A family of molecular nickel hydrogen evolution catalysts providing tunable overpotentials using ligand-centered proton-coupled electron transfer paths

2018 ◽  
Vol 54 (91) ◽  
pp. 12820-12823 ◽  
Author(s):  
Yutaro Aimoto ◽  
Keita Koshiba ◽  
Kosei Yamauchi ◽  
Ken Sakai
Keyword(s):  
Electron Transfer ◽  
Hydrogen Evolution ◽  
Proton Coupled Electron Transfer

The overpotential for H2 evolution from water can be rationally controlled by tuning the ligand-centered proton-coupled electron transfer (PCET) processes.

scholarly journals Role of pendant proton relays and proton-coupled electron transfer on the hydrogen evolution reaction by nickel hangman porphyrins

2014 ◽  
Vol 111 (42) ◽  
pp. 15001-15006 ◽  
Author(s):  
D. Kwabena Bediako ◽  
Brian H. Solis ◽  
Dilek K. Dogutan ◽  
Manolis M. Roubelakis ◽  
Andrew G. Maher ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Proton Coupled Electron Transfer

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 Electron–Nuclear Dynamics Accompanying Proton-Coupled Electron Transfer

2021 ◽  
Vol 143 (8) ◽  
pp. 3104-3112
Author(s):  
Yusuke Yoneda ◽  
S. Jimena Mora ◽  
James Shee ◽  
Brian L. Wadsworth ◽  
Eric A. Arsenault ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Nuclear Dynamics ◽  
Proton Coupled Electron Transfer
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