Photoelectrochemical Behavior of n-Type Si(111) Electrodes Coated With a Single Layer of Graphene
By Nielander, Adam C.; Bierman, Matthew J.; Petrone, Nicholas; Strandwitz, Nicholas C.; Ardo, Shane; Yang, Fan; Hone, James & Lewis, Nathan S.
Published in Journal of the American Chemical Society
2013
Abstract
The behavior of graphene-coated n-type Si(111) photoanodes was compared to the behavior of H-terminated n-type Si(111) photoanodes in contact with aqueous K3[Fe(CN)6]/K4[Fe(CN)6] as well as in contact with a series of outer-sphere, one-electron redox couples in nonaqueous electrolytes. The n-Si/Graphene electrodes exhibited stable short-circuit photocurrent densities of over 10 mA cm -2 for >1000 s of continuous operation in aqueous electrolytes, whereas n-Si -H electrodes yielded a nearly complete decay of the current density within ∼100 s. The values of the open-circuit photovoltages and the flat-band potentials of the Si were a function of both the Fermi level of the graphene and the electrochemical potential of the electrolyte solution, indicating that the n-Si/Graphene did not form a buried junction with respect to the solution contact.