title: Tuning the isoelectric point of graphene by electrochemical functionalization.
abstract: The ability to control the charge-potential landscape at solid-liquid interfaces is pivotal to engineer novel devices for applications in sensing, catalysis and energy conversion. The isoelectric point (pI)/point of zero charge (pzc) of graphene plays a key role in a number of physico-chemical phenomena occurring at the graphene-liquid interface. Supported by theory, we present here a methodology to identify the pI/pzc of (functionalized) graphene, which also allows for estimating the nature and extent of ion adsorption. The pI of bare graphene (as-prepared, chemical vapor deposition (CVD)-grown) is found to be less than 3.3, which we can continuously modify up to 7.5 by non-covalent electrochemical attachment of aromatic amino groups, preserving the favorable electronic properties of graphene throughout. Modelling all the observed results with detailed theory, we also show that specific adsorption of ions and the substrate play only an ancillary role in our capability to tune the pI of graphene.
authors.affiliation: Max Planck Institute for Solid State Research, D-70569 Stuttgart, Germany.
authors.forename: Laura
authors.initials: L
authors.lastname: Zuccaro
authors.affiliation: Max Planck Institute for Solid State Research, D-70569 Stuttgart, Germany.
authors.forename: Janina
authors.initials: J
authors.lastname: Krieg
authors.affiliation: Dept. of Biology, University of Rome Tor Vergata, I-00133 Rome, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Desideri
authors.affiliation: Max Planck Institute for Solid State Research, D-70569 Stuttgart, Germany.|Institut de Physique de la Matière Condensée, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland.
authors.forename: Klaus
authors.initials: K
authors.lastname: Kern
authors.affiliation: Max Planck Institute for Solid State Research, D-70569 Stuttgart, Germany.
authors.forename: Kannan
authors.initials: K
authors.lastname: Balasubramanian