title: Enhanced Performance of Si MIS Photocathodes Containing Oxide-Coated Nanoparticle Electrocatalysts.
abstract: Electrodepositing low loadings of metallic nanoparticle catalysts onto the surface of semiconducting photoelectrodes is a highly attractive approach for decreasing catalyst costs and minimizing optical losses. However, securely anchoring nanoparticles to the photoelectrode surface can be challenging-especially if the surface is covered by a thin insulating overlayer. Herein, we report on Si-based photocathodes for the hydrogen evolution reaction that overcome this problem through the use of a 2-10 nm thick layer of silicon oxide (SiOx) that is deposited on top of Pt nanoparticle catalysts that were first electrodeposited on a 1.5 nm SiO2|p-Si(100) absorber layer. Such insulator-metal-insulator-semiconductor (IMIS) photoelectrodes exhibit superior durability and charge transfer properties compared to metal-insulator-semiconductor (MIS) control samples that lacked the secondary SiOxoverlayer. Systematic investigation of the influence of particle loading, SiOxlayer thickness, and illumination intensity suggests that the SiOxlayer possesses moderate conductivity, thereby reducing charge transfer resistance associated with high local tunneling current densities between the p-Si and Pt nanoparticles. Importantly, the IMIS architecture is proven to be a highly effective approach for stabilizing electrocatalytic nanoparticles deposited on insulating overlayers without adversely affecting mass transport of reactant and product species associated with the hydrogen evolution reaction.
authors.affiliation: Department of Chemical Engineering, Lenfest Center for Sustainable Energy, Columbia University in the City of New York , 500 W. 120th St., New York, New York 10027, United States.
authors.forename: Natalie Y
authors.initials: NY
authors.lastname: Labrador
authors.affiliation: Department of Chemical Engineering, Lenfest Center for Sustainable Energy, Columbia University in the City of New York , 500 W. 120th St., New York, New York 10027, United States.
authors.forename: Xinxin
authors.initials: X
authors.lastname: Li
authors.affiliation: Department of Chemical Engineering, Lenfest Center for Sustainable Energy, Columbia University in the City of New York , 500 W. 120th St., New York, New York 10027, United States.
authors.forename: Yukun
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Materials Measurement Laboratory, National Institute of Standards and Technology , 100 Bureau Drive, Gaithersburg, Maryland 20878, United States.
authors.forename: Haiyan
authors.initials: H
authors.lastname: Tan
authors.affiliation: Materials Measurement Laboratory, National Institute of Standards and Technology , 100 Bureau Drive, Gaithersburg, Maryland 20878, United States.
authors.forename: Rongyue
authors.initials: R
authors.lastname: Wang
authors.affiliation: Department of Chemical Engineering, Lenfest Center for Sustainable Energy, Columbia University in the City of New York , 500 W. 120th St., New York, New York 10027, United States.
authors.forename: Jeffrey T
authors.initials: JT
authors.lastname: Koberstein
authors.affiliation: Materials Measurement Laboratory, National Institute of Standards and Technology , 100 Bureau Drive, Gaithersburg, Maryland 20878, United States.
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Moffat
authors.affiliation: Department of Chemical Engineering, Lenfest Center for Sustainable Energy, Columbia University in the City of New York , 500 W. 120th St., New York, New York 10027, United States.
authors.forename: Daniel V
authors.initials: DV
authors.lastname: Esposito
keywords: Photoelectrochemistry; UV-ozone; electrocatalysis; nanoparticles; photocatalysis; platinum; silicon; silicon dioxide