First examples of efficient participation of selected metal-ion-substituted heteropolyanions in electrocatalytic nitrate reduction

For the first time, to our knowledge, the electrocatalytic reduction of nitrate is achieved using heteropolyanions. Cu2+- and Ni2+- containing Dawson-type polyoxometalates proved efficient in this issue. The presence of these substituents seems necessary, in contrast with the observed catalytic reduction of nitrite and nitric oxide for which even non-substituted heteropolyanions were active. With the first series of derivatives, the electrocatalysis is triggered by the electrodeposited copper; Ni2+-containing heteropolyanions mimic more closely the catalytic reduction of nitrate by metal ion cyclams and related complexes. (C) 2001 Elsevier Science B.V. All rights reserved.