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Dr Simone Raugei

Pacific Northwest National Laboratory, Richland WA(USA)

Monday, September 9th, 2013 at 11:00:00 AM

Conference room Querzoli - LENS - via Nello Carrara 1 - Sesto Fiorentino (Florence)

Published on-line at 10:22:37 AM on Tuesday, September 3rd, 2013

Rational Design of Molecular Electrocatalysts for Production of H2 and Oxidation of H2

Recent advances in Ni-based bio-inspired catalysts obt ained in the Energy Frontier Research Center (EFRC) for Molecular Electrocatalysis at the Pacific

Recent  advances in Ni-based   bio-inspired catalysts obt ained   in  the Energy Frontier Research Center (EFRC)  for Molecular Electrocatalysis at  the  Pacific  Northwest  National Laboratory  demonstrated  the possibility of  cleaving  H2 or generating H2  with efficiency superior  to  that  of  hydrogenase  enzymes.   

 In these catalysts the transformation between  H 2  and  protons  proceeds  via                 an interplay between  proton,  hydride  and  electron  transfer  steps  and  involves  the interaction  of  a dihydrogen  molecule with both a Ni(II)  center  and with pendant amine  bases                 incorporated   in  a  six-membered ring, whi ch   act as  proton  relays. 

 By using   ab initio molecular dynamics ,free energy calculations  and microkinetic modeling, we have carried out  an  exhaustive  characterization  of  these  molecular catalysts. It will be shown  that the metal center  and the pendant amine    act as a frustrated Lewis acid/base  pairs,  making  the  heterolytic  H 2  bond cleavage   or formation facile processes. A detailed microkinetic  modeli ng  of  the  catalytic cycle reveals  the importance  of  precisely controlled  delivery  of  protons   to  avoid  catalytically  inefficient pathways. Toward  the  rational  design  of catalysts with optimal  rates  and  overpotentials, we are devel oping  linear  free  energy rel ationships, based  on  extensive ab initio thermodynamic and     kinetic data,  to  be  employed  in  a  theoretically  driven  refinement  of catalysts using  macrokinetic  analysis.                                     

Acknowledgments       

This research was  supported as  part  of  the  Center  for  Molecular  Electrocatalysis,  an Energy Frontier Research Center funded   by the  US Department  of  Energy, Office of Science,Office               of Basic Energy Sciences. 

For further informations, please contact Prof. Roberto Righini.