Synthesis and Characterization of ZrO2/C as Electrocatalyst for Oxygen Reduction to H2O2

Abstract

Electrogeneration of hydrogen peroxide (H2O2) has potential application in advanced oxidation processes. Amorphous carbon is well known as catalyst for oxygen reduction reaction (ORR) through two-electron pathway. However, modification of the carbon can improve its selectivity for the H2O2 electrogeneration. In the present study, we investigated the properties of ZrO2 nanoparticles supported on carbon black (Printex L6) as electrocatalyst for H2O2 production in acidic medium. The catalytic activity of ZrO2/C for oxygen reduction to H2O2 is higher than the catalytic activity of treated carbon black. The highest selectivity of the ZrO2/C catalyst for H2O2 production is attributable to the presence of oxygenated functional groups on its surface and consequently increase of the surface hydrophilicity in comparison with treated carbon black. This surface effect leads to highest H2O2 electrogeneration, which is shown as a high current efficiency (I(H2O2)%). In fact, increased H2O2 yields from 74.5 to 84.2% were observed for the treated carbon black and ZrO2/C catalysts, respectively, whereas the I(H2O2)% for the unmodified carbon black was 65.3%. Furthermore, the modification of carbon by ZrO2 nanoparticles shifted the ORR half-wave potential towards ca. 137 mV, indicating lower energy consumption for producing H2O2. Thus, the ZrO2/C nanoparticles are shown to be promising electrocatalysts for environmental applications.