HYDRIDIC AND ELECTROCATALYTIC PROPERTIES OF HYPO-HYPER-D-ELECTRONIC COMBINATIONS OF TRANSITION-METAL INTERMETALLIC PHASES

Hydridic and electrocatalytic properties of hypo-hyper-d-electronic co mbinations of transition metals in their intermetallic phases and allo ys for the hydrogen storage, hydridic batteries and its electrode reac tions (HELR) have been considered in the light of Fermi dynamics (or t he electronic density of states), work function and the Brewer or Mied ema intermetallic bonding theory (structural factors). It has been poi nted out that such an intermetallic hypo-hyper-d-electronic interactio n of transition metals (or the doped effect of a hyper-d- upon the bul k or surface of a hypo-d-electronic metal, or vice versa), which leads to the defined optimal mutual (bulk or surface) electronic density of states for both hydridic storage and/or electrocatalytic reaction (ca thodic evolution (HER) and/or anodic oxidation (HOR) of hydrogen), imp oses the same catalytic effect as the Non-Faradaic promotion by induce d polarization, or the so-called NEMCA effect (Non-Faradaic Electroche mical Modification of Catalytic Activity). The main impact has been im posed on the most promising hydridic battery system (Ti-Ni, crystallin e and sintered), as well as on typical electrocatalytic issues (Mo-Co, Mo-Ni, Zr-Ni). It has also been inferred that each phase diagram of a hypo-hyper-d-electronic combination of transition metals behaves in b oth the hydridic and electrocatalytic sense as the part of Periodic Ta ble: intermetallic phases and alloys between two pure constituents obe y typical volcano plots for both hydridic and catalytic activity in ac cordance with the changes in their electronic density of states and we ll-defined crystal structure, thereby resulting in intermetallic bondi ng effectiveness and a mutual work function. (C) 1998 International As sociation for Hydrogen Energy.