title: Metal-Free Motifs for Solar Fuel Applications.
abstract: Metal-free motifs, such as graphitic carbon nitride, conjugated polymers, and doped nanostructures, are emerging as a new class of Earth-abundant materials for solar fuel devices. Although these metal-free structures show great potential, detailed mechanistic understanding of their performance remains limited. Here, we review important experimental and theoretical findings relevant to the role of metal-free motifs as either photoelectrodes or electrocatalysts. First, the light-harvesting characteristics of metal-free photoelectrodes (band energetics, exciton binding energies, charge carrier mobilities and lifetimes) are discussed and contrasted with those in traditional inorganic semiconductors (such as Si). Second, the mechanistic insights into the electrocatalytic oxygen reduction and evolution reactions, hydrogen evolution reaction, and carbon dioxide reduction reaction by metal-free motifs are summarized, including experimental surface-sensitive spectroscopy findings, studies on small molecular models, and computational modeling of these chemical transformations.
authors.affiliation: Department of Chemistry, Center for Photochemical Sciences, Bowling Green State University, Bowling Green, Ohio 43403; email: ilics@bgsu.edu , mzoric@bgsu.edu , ushap@bgsu.edu , yunjinh@bgsu.edu , kglusac@bgsu.edu.
authors.forename: Stefan
authors.initials: S
authors.lastname: Ilic
authors.affiliation: Department of Chemistry, Center for Photochemical Sciences, Bowling Green State University, Bowling Green, Ohio 43403; email: ilics@bgsu.edu , mzoric@bgsu.edu , ushap@bgsu.edu , yunjinh@bgsu.edu , kglusac@bgsu.edu.
authors.forename: Marija R
authors.initials: MR
authors.lastname: Zoric
authors.affiliation: Department of Chemistry, Center for Photochemical Sciences, Bowling Green State University, Bowling Green, Ohio 43403; email: ilics@bgsu.edu , mzoric@bgsu.edu , ushap@bgsu.edu , yunjinh@bgsu.edu , kglusac@bgsu.edu.
authors.forename: Usha Pandey
authors.initials: UP
authors.lastname: Kadel
authors.affiliation: Department of Chemistry, Center for Photochemical Sciences, Bowling Green State University, Bowling Green, Ohio 43403; email: ilics@bgsu.edu , mzoric@bgsu.edu , ushap@bgsu.edu , yunjinh@bgsu.edu , kglusac@bgsu.edu.
authors.forename: Yunjing
authors.initials: Y
authors.lastname: Huang
authors.affiliation: Department of Chemistry, Center for Photochemical Sciences, Bowling Green State University, Bowling Green, Ohio 43403; email: ilics@bgsu.edu , mzoric@bgsu.edu , ushap@bgsu.edu , yunjinh@bgsu.edu , kglusac@bgsu.edu.
authors.forename: Ksenija D
authors.initials: KD
authors.lastname: Glusac
keywords: carbon nitride; conjugated polymers; doped; electrocatalyst; graphene; photoelectrode