title: Tandem Core-Shell Si-Ta3N5Photoanodes for Photoelectrochemical Water Splitting.
abstract: Nanostructured core-shell Si-Ta3N5photoanodes were designed and synthesized to overcome charge transport limitations of Ta3N5for photoelectrochemical water splitting. The core-shell devices were fabricated by atomic layer deposition of amorphous Ta2O5onto nanostructured Si and subsequent nitridation to crystalline Ta3N5. Nanostructuring with a thin shell of Ta3N5results in a 10-fold improvement in photocurrent compared to a planar device of the same thickness. In examining thickness dependence of the Ta3N5shell from 10 to 70 nm, superior photocurrent and absorbed-photon-to-current efficiencies are obtained from the thinner Ta3N5shells, indicating minority carrier diffusion lengths on the order of tens of nanometers. The fabrication of a heterostructure based on a semiconducting, n-type Si core produced a tandem photoanode with a photocurrent onset shifted to lower potentials by 200 mV. CoTiOxand NiOxwater oxidation cocatalysts were deposited onto the Si-Ta3N5to yield active photoanodes that with NiOxretained 50-60% of their maximum photocurrent after 24 h chronoamperometry experiments and are thus among the most stable Ta3N5photoanodes reported to date.
authors.forename: Ieva
authors.initials: I
authors.lastname: Narkeviciute
authors.forename: Pongkarn
authors.initials: P
authors.lastname: Chakthranont
authors.forename: Adriaan J M
authors.initials: AJ
authors.lastname: Mackus
authors.affiliation: SLAC National Accelerator Laboratory , 2575 Sand Hill Road, Menlo Park. California 94025, United States.
authors.forename: Christopher
authors.initials: C
authors.lastname: Hahn
authors.forename: Blaise A
authors.initials: BA
authors.lastname: Pinaud
authors.forename: Stacey F
authors.initials: SF
authors.lastname: Bent
authors.affiliation: SLAC National Accelerator Laboratory , 2575 Sand Hill Road, Menlo Park. California 94025, United States.
authors.forename: Thomas F
authors.initials: TF
authors.lastname: Jaramillo
keywords: Heterojunction; charge transport; heterostructure; oxygen evolution reaction; photoanode; photoelectrochemical water oxidation