Molybdenum carbonyl complexes as HER electrocatalysts

Abstract Four cyclopentadienyl and allylic molybdenum carbonyl complexes have been prepared and tested as proton reduction electrocatalysts using trifluoroacetic acid as the proton source in acetonitrile. Cyclic voltammetry studies showed that these complexes are able to function as moderate electrocatalysts with overpotentials of about 0.9 V and catalytic efficiency of up to 60%. The average turnover number and turnover frequency for each of the molybdenum catalyst measured over a five-hour period have been calcualted to be in the range of 16–24 and 3.2 h−1 to 5.4 h−1 respectively for 1 mM catalyst and 20 acid equivalent. A mechanism to account for the proton reduction process is also proposed based on the electrochemical and spectroscopic measurements.