title: Volcano plots in hydrogen electrocatalysis - uses and abuses.
abstract: Sabatier's principle suggests, that for hydrogen evolution a plot of the rate constant versus the hydrogen adsorption energy should result in a volcano, and several such plots have been presented in the literature. A thorough examination of the data shows, that there is no volcano once the oxide-covered metals are left out. We examine the factors that govern the reaction rate in the light of our own theory and conclude, that Sabatier's principle is only one of several factors that determine the rate. With the exception of nickel and cobalt, the reaction rate does not decrease for highly exothermic hydrogen adsorption as predicted, because the reaction passes through more suitable intermediate states. The case of nickel is given special attention; since it is a 3d metal, its orbitals are compact and the overlap with hydrogen is too low to make it a good catalyst.
authors.affiliation: PRELINE, Universidad Nacional del Litoral, Santa Fe, Argentina ; Institute of Theoretical Chemistry, Ulm University, D-89069 Ulm, Germany.
authors.forename: Paola
authors.initials: P
authors.lastname: Quaino
authors.affiliation: Institute of Theoretical Chemistry, Ulm University, D-89069 Ulm, Germany.
authors.forename: Fernanda
authors.initials: F
authors.lastname: Juarez
authors.affiliation: Institute of Theoretical Chemistry, Ulm University, D-89069 Ulm, Germany ; Faculdad de Matemática, Astronomía y Física, IFEG-CONICET, Universidad Nacional de Córdoba, Córdoba, Argentina.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Santos
authors.affiliation: Institute of Theoretical Chemistry, Ulm University, D-89069 Ulm, Germany.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Schmickler
keywords: Sabatier’s principle; electrocatalysis; hydrogen evolution; volcano curve