Molybdenum-sulfur dimers as electrocatalysts for the production of hydrogen at low overpotentials.
(CpMomu-S)2S2CH2, 2, and related derivatives serve as electrocatalysts for the reduction of protons with current efficiencies near 100%. The kinetics of the electrochemical reduction process has been studied, and the effects of varying the proton source, the solvent, the cyclopentadienyl substituents, and the sulfur substituents on the catalyst have been examined. The reduction of excess p-cyanoanilinium tetrafluoroborate under a hydrogen atmosphere in 0.3 M Et4NBF4/acetonitrile buffered at pH 7.6 is catalyzed by 2 at -0.64 V versus ferrocene, with an overpotential of 120 mV. Protonation of the sulfido ligand in 2 is an initial step in the catalytic process, and the rate-determining step at high acid concentrations appears to be the elimination of dihydrogen. The elimination may occur either from adjacent hydrosulfido sites or from a hydrosulfido-molybdenum hydride intermediate.
Appel
Aaron M
AM
Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309, USA.
DuBois
Daniel L
DL
DuBois
M Rakowski
MR
D002384:Catalysis; D019281:Dimerization; D004563:Electrochemistry; D006859:Hydrogen / Q000737:chemistry*; D015394:Molecular Structure; D008982:Molybdenum / Q000737:chemistry*; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D010084:Oxidation-Reduction; D012997:Solvents / Q000737:chemistry; D013237:Stereoisomerism; D013455:Sulfur / Q000737:chemistry*; D013816:Thermodynamics
D009942:Organometallic Compounds; D012997:Solvents; D013455:Sulfur; D006859:Hydrogen; D008982:Molybdenum