Electrode-adsorption activates trans-[Cr(cyclam)Cl2]+ for electrocatalytic nitrate reduction

Cyclic voltammetry reveals that aqueous trans-[Cr(cyclam)Cl-2](+) is reversibly reduced at a mercury electrode, with a small prewave suggesting an adsorptive interaction between the complex and electrode surface. A catalytic current is observed in the presence of excess nitrate, with the onset potential for catalysis at the prewave. Nitrate is electrocatalytically reduced to nitrite, with preliminary mechanistic investigations implicating a chromium oxo intermediate.