Electrocatalytic Reduction of NO

Electrocatalytic reduction of NOs" takes place efficiently in the presence of a catalytic amount of Co(III)(cyclam) or Ni(II)(cyclam) in aqueous media at a mercury cathode (Scheme 99) [403]. 

The electrocatalytic reduction of NOs" ions on noble metal electrodes has been the subject of several studies. (The reduction of nitrate has recently gained renewed attention in view of its relevance to pollution control.)... 

It follows from a comparison of Fig. 5(b) and (c) with Fig. 6(b) and (c) that the electrocatalytic reduction of NOs" ions depends strongly on structural factors, reflected by the voltammetric behavior in pure FI2SO4 solution. This observation is in accordance with earlier findings [173, 233, 234] that (100) crystal faces have an excellent catalytic activity toward the reduction of N03 ions compared with the other low index planes. 

Figure 4.10. Proposed mechanism for electrocatalytic reduction of NO or NO, as per Bedioui. ...

Gootzen JFE, Peeters PGJM, Dukers JMB, Lefferts L, Visscher W, Van Veen JAR (1997) The electrocatalytic reduction of NO- 3 on Pt, Pd and Pt -l- Pd electrodes activated with Ge. J Electroanal Chem 434 171-183... 

Cooperative effect of Mn- and Fe-centers within Mn2Fe2P4W3o in the electrocatalytic reduction of nitrite In the preceding sections, it was well established that Fe(III)-substituted POMs catalyze the reduction of NO and/or N02 [1]. The first step in this process is the formation of a complex with the Fe(II) form of the POM and nitrogen oxide. 

In contrast, experiments with pure NO [10, 155] at pH = 5 show that the catalytic process starts directly in the iron reduction-potential domain. We have also checked the catalytic reduction of NO at pH = 1. All these results converge to designate NO as the species electrocatalytically reduced by the present complexes throughout the pH domain evaluated. 

When the cytochrome d functionalized electrode was exposed to a nitric oxide an increase in the reduction current was observed due to coordination and subsequent oxidation followed by an electrocatalytic reduction of the biomolecule. This can also be used in an amperometric mode for NO-biosensing [56,151]. 

However, Hori (1986) found the electrocatalytic reduction of carbon dioxide to methane on a molybdenum cathode to be electrocatalytic [11]. One hundred percent reduction of carbon dioxide to methanol at 0°C was reported. What remains open to research is the use of nonaqueous solvents, for example, acetonitrile, because there would be then no competition from hydrogen evolution. Carbon dioxide does undergo electrochemical reduction in acetonitrite to glycolic acid. Here is a research topic, which could have world consequences and cost very little (about 105 per year per researcher, even a dozen would make a great difference in five years). 

Others have fabricated PPy nanowires by template-free potentiostatic polymerization in LiC104 and Na2C03 [3,4], which leads to the formation of disordered polymer mats at the electrode surface. These electrodes were used for the electrocatalytic reduction of nitrite and the oxidation of ascorbic acid. However, no comparisons were made between the nanostructured surfaces and bulk electropolymerized films. 

Developments of all the three strategies as applied to the redox processes of the NOx continue unabated [43-47] every time a new chemical shows promise for electrocatalytic reduction of the NO . There are several recent examples, which cannot be cited exhaustively. In particular, the electrocatalytic reduction of nitrite has become a popular test of the electrocatalytic behaviors of polyoxomet-alates [48-52]. 

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