Novel ruthenium based electrocatalyst for the convenient reduction of nitrogen-nitrogen bonds in azide to ammonia in aqueous solution

摘要

The interaction of azide (N_3~-) ion, at pH 5.3 with [Ru~(III)(EDTA) (H_2O)]~- (EDTA = ethylenediaminetetraacetate) was studied in aqueous solution by polarography and cyclic voltammetry. The product, [Ru~(III)(EDTA)(N_3)]~(2-) showed a multi-electronreduction step, which,is polarographically reversible but, cyclic voltammetrically irreversible, in the potential range - 0-1 to — 02 V vs SCE. This reduction step, which was different from the one-electron reduction step of CRu~(III)(EDTA)(H_2O)]; (E~(1/2) = - 0.113 V vs SCE) was assigned to the reduction of the coordinated azide ion to ammonia by the irreversible transfer of electrons from Hg-electrode via ruthenium metal. Azide, at pH 5.3, was reduced, electrolytically, for the first time, to ammonia at Hg-pooi cathode mediated by [Ru~(III)(EDTA) (N_3)]~(2-). The turnover number with respect to the formation of ammonia (moles of ammonia per mole of ruthenium per hour) was obtained from the constant potential electrolysis data. On the basis of experimental observations, a probable mechanism has been proposed for the electrocatalytic reduction of azide to ammonia in aqueous solution.