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 nit rate 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 redu ction of nitrite and nitric oxide for which even non-substituted heteropoly anions were active. With the first series of derivatives, the electrocataly sis is triggered by the electrodeposited copper; Ni2+-containing heteropoly anions mimic more closely the catalytic reduction of nitrate by metal ion c yclams and related complexes. (C) 2001 Elsevier Science B.V. All rights res erved.