Methoxyazobenzene as universal catalyst of four-electron oxygen reduction in fuel cells in a wide range of pH

The oxygen reduction reaction (ORR) continues to be in the center of attention because of its role in the so-called green, electrochemical energy conversion. The main problem related to the oxygen reduction reaction is its slow kinetics on different electrode materials. In this work, methoxyazobenzene (MA) in the form of a thin film on a conductive support was tested as a catalyst for ORR in electrolytes of different pH values. The electrode modified with methoxyazobenzene demonstrated activity for ORR catalysis in electrolytes of all tested pH values. It was shown that the direct four-electron mechanism is dominant during the development of ORR on the electrode modified with methoxyazobenzene. The exchange current density increased noticeably with increasing temperature from 25 to 65 °C. The activation energy of the reaction was found to be 25 kJ mol-1.