On the catalytic behavior of copper toward oxygen reduction reaction in alkaline solution



The kinetic and mechanistic aspects of the oxygen reduction reaction as well as the electrocatalytic effect of copper surface in alkaline solution were studied by cyclic voltammetry and rotating disk electrode technique. In the potential range of -0.4 to -1.4 V/SCE time dependent cathodic peaks at -0.9 V/SCE, -1.2 V/SCE and plateau extending through this domain were observed. Direct reduction of oxygen along with the dominating reduction of copper oxides which formed during time delay at open circuit potential is discussed in the light of electrochemical techniques. The number of electrons transferred per O2 molecule (n) obtained on different copper surface is close to 4 on oxide free surface and gradually decreases to 2 when the oxide layers cover the copper surface. Moreover calculation of rate constant of oxygen reduction on copper surface, demonstrated a faster kinetic of reaction on oxide free surface of copper. Tearing down and building up of the surface causing increased surface area is also observed.