Hypo–hyper- d-electronic interactive nature of synergism in catalysis and electrocatalysis for hydrogen reactions

Abstract

The nature, causes and consequences of the existence of volcano plots along transition series with resulting theoretical conclusions have been extended on the Brewer hypo–hyper- d-electronic combinations of both intermetallic phases and interionic composites. It has been pointed out that every such phase diagram behaves in electrocatalytic properties as the part of Periodic Table between initial constituents or their periods, and thereby features the Gschneidner type of volcano curve for the hydrogen electrode reactions (helr), in common with the well known electrocatalytic volcano plots for the hydrogen evolution reaction (her) upon individual transition metals. Several characteristic Brewer type intermetallic systems (Ti–Ni, Zr–Ni, Mo–Ni, Mo–Pt) were investigated and their comparable electrocatalytic and hydridic properties were revealed from volcanic plots along the corresponding phase diagrams. Electrocatalysis appears as the hypo–hyper- d-electronic interactive effect of transition element composites either within metallic lattice, or their ions upon the substrate surface.