The energy saving mechanism of gas diffusion electrode based on Pt/C catalyst for saving energy and green electrodeposition of manganese dioxide

•The electricenergy consumption of the electrolysis with Pt/C GDE can save 60% at 80 A/m2.•The oxygen reduction reaction of Pt/C GDE, rather than the hydrogen evolution reaction of the traditional cathode (Cu), is used in electrodeposition of manganese dioxide.•The oxygen reduction reaction of Pt/C GDE adopts a 4-electron transfer process as the main process in electrolyte (O2 + 4H+ + 4e− → 2H2O).

The electrodeposition of manganese dioxide is obtained by using Pt/C GDE rather than the traditional electrode (Cu) in order to save energy and protect the environment. Thus, the energy-saving mechanism of Pt/C gas diffusion electrode (Pt/C GDE) in high temperature and strong acid MnSO4 media is studied. The cell voltage and the cathode potential of Pt/C GDE and Cu electrode are tested in 30 g/dm3 H2SO4 + 120 g /dm3 MnSO4 at 80 ± 2 °C to exhibit the energy-saving effect. The results show that the cell voltage can be reduced more than 1.13 V using Pt/C GDE as cathode instead of the traditional electrode (Cu), and the electric energy consumption of electrolysis with Pt/C GDE can save 60% at 80 A/m2. The CV curves and polarization curves of Pt/C GDE and the polarization curve of hydrogen evolution reaction on a Cu electrode are researched. The results indicate that the polarization curve of Cu electrode is much more negative than that of the Pt/C GDE at same current density. The reaction of Pt/C GDE is oxygen reduction at the cathode.The amperometric oxygen reduction current of the GDE with Pt/C is about 28 times higher than that of GDE without Pt/C at 0.4 V vs. Ag/AgCl. The Pt/C catalyst particle sizes range from 2 nm–6 nm by HRTEM. The oxygen reduction reaction mechanism of Pt/C GDE is researched in strong acid containing manganese ion by rotating disk electrode (RDE). The DO2DO2 and CO2CO2 values are 0.715 × 10−9 m2s−1 and 3.3 mol · m−3 in electrolyte. Koutecky-Levich analysis indicates that the oxygen reduction reaction of Pt/C GDE adopts a 4electron transfer process as main process as the main process in electrolyte (O2 + 4H+ + 4e− → 2H2O). Therefore, the major causes of the new method for saving energy is that the oxygen reduction reaction of Pt/C GDE, rather than the hydrogen evolution reaction of tradition cathode (Cu), is used, and that the high catalytic activity (the 4-electron transfer process) of Pt/C catalyst also contributes.

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