Zirconia on Reduced Graphene Oxide Sheets: Synergistic Catalyst with High Selectivity for H2O2 Electrogeneration

In situ electrogeneration of hydrogen peroxide through the oxygen reduction reaction (ORR) represents a potentially greener route for wastewater treatment. However, the development of adequate catalysts following a two-electron pathway with high selectivity and low overpotential is still of great importance. To address this issue, nanoparticles of zirconium oxide supported on reduced graphene oxide (rGO) sheets were prepared by hydrothermal reaction, and the composite catalysts were tested for ORR in both acid and alkaline media. The presence of zirconium oxides (ZrO2-x and ZrO2) improved significantly the activity of rGO to ORR and its selectivity to H2O2 electrogeneration. Indeed, an increase from 73.7% to 89.5% was obtained in acid solution, and from 72.9% to 83.1% in alkaline medium. The high activity of the composite catalysts is assigned to the synergistic effect between the ZrO2-x and rGO. The highest selectivity for the H2O2 electrogeneration was correlated to the presence of ZrO2 phase. In addition, the zirconia-rGO catalysts are stable and reusable. Therefore, these composites are very promising catalysts to be used in gas diffusion electrodes for Advanced Oxidation Processes.