Volcanic periodicity plots along transition series, hypo-hyper-d-d-interelectronic correlations and electrocatalysis for hydrogen electrode reactions

Abstract

Volcano plots of various physical and chemical properties along transition series reveal the periodicity features of elements based on the d-d-electronic correlations, with rather similar equivalent shape, and consequently, when plotted into one another, yield various relevant linear interdependences. As the consequence, the d-band has been inferred and confirmed for the bonding, adsorptive and catalytic orbital. Such state of evidence leads to the conclusion that on the same way every hypo-hyper-d-d-interelectronic phase diagram behaves similar (local) volcano dependence as the part of the Periodic Table between two initial periods of interacting ingredients. In other words, their intermetallic phases of the same average d-electronic configuration replace the (‘missing’) elements in their energy state and behaviour in between, and consequently, have been used to assess the synergistically active electrocatalysts for the hydrogen electrode reactions from the peak values of the corresponding volcano plots. In the same context, the general hypsometric type of kinetic relations, including the Boltzmann-Maxwell distribution law that implies the exponential energy dependence, brings various energy states in mutual linear interdependence with the logarithm of the reaction rates.