Dramatic increase in the oxygen reduction reaction for platinum cathodes from tuning the solvent dielectric constant.
Hydrogen fuel cells (FC) are considered essential for a sustainable economy based on carbon-free energy sources, but a major impediment are the costs. First-principles quantum mechanics (density functional theory including solvation) is used to predict how the energies and barriers for the mechanistic steps of the oxygen reduction reaction (ORR) over the fcc(111) platinum surface depend on the dielectric constant of the solvent. The ORR kinetics can be strongly accelerated by decreasing the effective medium polarizability from the high value it has in water. Possible ways to realize this experimentally are suggested. The calculated volcano structure for the dependence of rate on solvent polarization is considered to be general, and should be observed in other electrochemical systems.
CNR-ICCOM and IPCF, Consiglio Nazionale delle Ricerche via Giuseppe Moruzzi 1, 56124 Pisa (Italy); Materials and Process Simulation Center, California Institute of Technology, MC 139-74, Pasadena, CA 91125 (USA). alessandro.fortunelli@cnr.it, afloer@caltech.edu.
Alessandro
A
Fortunelli
William A
WA
Goddard
Yao
Y
Sha
Ted H
TH
Yu
Luca
L
Sementa
Giovanni
G
Barcaro
Oliviero
O
Andreussi
density functional calculations; electrochemistry; hydrogen fuel cells; reaction energy barriers; solvation