**6. Conclusion**

It was shown that the electrochemical reduction of nitric oxide in an atmosphere containing excess oxygen is not effective due to the low selectivity of the cathode materials. To solve the problem of effective electrochemical reduction of nitric oxide in the presence of the excess oxygen *S.Bredikhin et al.* (Awano et al., 2004b; Bredikhin et al., 2001a, 2001b) proposed the concept of artificially designed multilayer structure which should operate as an electrode with high selectivity. Our investigations have shown that substitution of traditional cathodes by the multilayer electro-catalytic electrode with an electrochemically assembled nanostructure leads to a dramatic decrease in the value of the electrical power required for NO decomposition. It was shown that multilayer electro-catalytic electrode should consist at list from three main functional layers: Cathode; Electro-catalytic electrode; Covering layer, in order to operate as an electrode with high selectivity. In 2008 *K.Hamamoto et.al.* (Hamamoto et al., 2008) proposed to use an electrochemical reactor with fourth additional NOx adsorption layer. The values of current efficiency in such reactors increase up to 20% and the values of the NO/O2 selectivity up to 25. These results indicate that this new type of electro-catalytic reactor can be used for practical applications. From our point of view, such systems should substitute traditional catalytic systems for exhaust gas purification.
