Cost-effective electrogeneration of H2O2 utilizing HNO3 modified graphite/polytetrafluoroethylene cathode with exterior hydrophobic film.

Electrochemical 2-electrons oxygen reduction process has been regarded as the effective strategy for H2O2 generation in wastewater treatment. However, its large-scale application is still limited by the relatively high cost of the carbon materials and short-term stability. In this study, a nitric acid modified graphite/polytetrafluoroethylene (PTFE) composite cathode with exterior hydrophobic film was fabricated for cost-effective electrogeneration of hydrogen peroxide (H2O2). Experimental results show that 2 M HNO3 modification rendered the introduction of much more defect sites and oxygen/nitrogen-containing groups on graphite. As a result, H2O2 electrogeneration was 3.0 times as much as that of virgin graphite counterpart at 3 mA cm-2. Moreover, the additional introduction of exterior hydrophobic film on the as-prepared graphite/PTFE cathode did not only further promote H2O2 electrogeneration, but also endowed the cathode with strong hydrophobic stability. As for the modified cathode with exterior hydrophobic film, the influence of mass graphite/PTFE binder ratio (1:1-4:1) and pH (3.0-9.0) on H2O2 electrogeneration was slight, but the current density (3.0-15 mA cm-2) had evident effect on H2O2 electrogeneration. Generally, owing to its low price and being easily available, the modified graphite would be cost-effectively utilized to prepare the gas diffusion cathode for the large-scale electrogeneration of H2O2 in industry.