Semiconductor Electrodes. XXXIII. Photoelectrochemistry of n-Type WSe2 in Acetonitrile

摘要

The photoelectrochemical behavior of n-type WSe2 single crystal electrodes in acetonitrile solutions containing several redox couples was investigated. Electrodes with discontinuities in the van der Waals' surface show large dark currents and recombination of electrons with photooxidized solution species. Pretreatment of such a surface with Cl(-) passivates these dark active sites and increases the photocurrent density. The observed photopotentials at WSe2 for redox couples with potentials, V sub redox, more positive than 0.5 V vs SCE show behavior consistent with Fermi level pinning; the onset potential of photocurrents increases linearly with increasing V sub redox while the photopotential remains constant. The energy position at which pinning occurs depends on the density of surface states and the concentration of solution species.