Abstract
Various electrodes modified with cobalt‐porphyrin‐clay complexes (CoTMPyP‐ and CoTAPP‐Mon, Ver, and AW‐Kao), silver colloid (AgCol), and polymers [PVA and P(2VPy)] were synthesized and their electrochemical properties were investigated to evaluate the possibility of creating oxygen sensors. The oxygen reduction based on the two‐electron transfer mechanism (Eq. 1) occurred in the cobalt‐porphyrin‐clay/AgCol/polymer‐modified electrode and the peak current density
depended quantitatively on the concentration of oxygen. As for the evaluation of oxygen sensors in the modified electrode systems at the optimal composition, (i) the 
increased linearly with the concentration of oxygen, (ii) the response was a reversible and rapid one, and (iii) the modified electrodes in the Mon and Ver systems were most stable 
. The cobalt‐porphyrin‐clay/AgCol/polymer‐modified electrode systems acted effectively as oxygen sensors.