title: Rational design of carbon nitride photocatalysts by identification of cyanamide defects as catalytically relevant sites.
abstract: The heptazine-based polymer melon (also known as graphitic carbon nitride, g-C3N4) is a promising photocatalyst for hydrogen evolution. Nonetheless, attempts to improve its inherently low activity are rarely based on rational approaches because of a lack of fundamental understanding of its mechanistic operation. Here we employ molecular heptazine-based model catalysts to identify the cyanamide moiety as a photocatalytically relevant 'defect'. We exploit this knowledge for the rational design of a carbon nitride polymer populated with cyanamide groups, yielding a material with 12 and 16 times the hydrogen evolution rate and apparent quantum efficiency (400 nm), respectively, compared with the unmodified melon. Computational modelling and material characterization suggest that this moiety improves coordination (and, in turn, charge transfer kinetics) to the platinum co-catalyst and enhances the separation of the photogenerated charge carriers. The demonstrated knowledge transfer for rational catalyst design presented here provides the conceptual framework for engineering high-performance heptazine-based photocatalysts.
authors.affiliation: Max Planck Institute for Solid State Research, Heisenbergstraße 1, 70569 Stuttgart, Germany.|Department of Chemistry, University of Munich, Butenandtstraße 5-13, 81377 Munich, Germany.
authors.forename: Vincent Wing-Hei
authors.initials: VW
authors.lastname: Lau
authors.affiliation: Max Planck Institute for Solid State Research, Heisenbergstraße 1, 70569 Stuttgart, Germany.
authors.forename: Igor
authors.initials: I
authors.lastname: Moudrakovski
authors.affiliation: Department of Mechanical Engineering and Materials Science, Duke University, Durham, North Carolina 27708, USA.
authors.forename: Tiago
authors.initials: T
authors.lastname: Botari
authors.affiliation: Max Planck Institute for Solid State Research, Heisenbergstraße 1, 70569 Stuttgart, Germany.|Department of Chemistry, University of Munich, Butenandtstraße 5-13, 81377 Munich, Germany.
authors.forename: Simon
authors.initials: S
authors.lastname: Weinberger
authors.affiliation: Inorganic Chemistry III, University of Bayreuth, Universitätsstraße 30, 95447 Bayreuth, Germany.
authors.forename: Maria B
authors.initials: MB
authors.lastname: Mesch
authors.affiliation: Max Planck Institute for Solid State Research, Heisenbergstraße 1, 70569 Stuttgart, Germany.
authors.forename: Viola
authors.initials: V
authors.lastname: Duppel
authors.affiliation: Inorganic Chemistry III, University of Bayreuth, Universitätsstraße 30, 95447 Bayreuth, Germany.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Senker
authors.affiliation: Department of Mechanical Engineering and Materials Science, Duke University, Durham, North Carolina 27708, USA.
authors.forename: Volker
authors.initials: V
authors.lastname: Blum
authors.affiliation: Max Planck Institute for Solid State Research, Heisenbergstraße 1, 70569 Stuttgart, Germany.|Department of Chemistry, University of Munich, Butenandtstraße 5-13, 81377 Munich, Germany.|Nanosystems Initiative and Center for Nanoscience (CeNS), Schellingstraße 4, 80799 Munich, Germany.
authors.forename: Bettina V
authors.initials: BV
authors.lastname: Lotsch