Electroreduction-oxidation of CO2 was studied by anodic stripping voltammetry on different SPE electrodes. The catalytic capacity of these electrodes for CO2 electroreduction was examined by comparing the oxidation charges of both the products (R(CO2)) produced by electroreduction of CO2 (Q(ox)) and the adsorbed hydrogen (Q(H)). SEM analysis was used to understand the catalytic capacity of different electrodes. A new electrochemical system based on a PtAu-SPE electrode, which had the best comprehensive catalytic capacity among the investigated electrodes, showed a satisfactory linear response (Q(ox)) to CO2 concentration in the range 0-40% when adsorption time t(ad)less than or equal to1 min. In addition, this system possessed advantages such as no leakage, high efficiency, excellent reproducibility and good stability. Furthermore, the composition of R( CO2) on the Pt-SPE and the Pt alloy-SPE electrodes was investigated by XPS analysis.