a b s t r a c tHighly efficient H 2 O 2 electrogeneration is required in the Advanced Oxidation Process for organic wastewater treatment. However, the development of more efficient catalytic particles used in gas diffusion electrodes (GDEs) to enable the oxygen reduction reaction through two-electron transfer is still of great importance. The performance of the Ta 2 O 5 nanoparticles on carbon black in catalyzing the ORR was evaluated using rotating ring-disk electrode. The current efficiency for H 2 O 2 electrogeneration on Ta 2 O 5 /C catalyst is 83.2% whereas carbon black exhibits 65.3%. GDEs were constructed using carbon black either unmodified or modified with Ta 2 O 5 nanoparticles. The modified GDE produces 27.9 mg L −1 of H 2 O 2 , while the unmodified GDE generates 19.1 mg L −1 of H 2 O 2 . Furthermore, the energy consumption for the H 2 O 2 electrogeneration is lower in modified than in unmodified GDE (15.0 kW h vs. 18.8 kW h). The high performance of the GDE (Ta 2 O 5 /C) renders it a viable alternative cathode in the electrochemical treatment of wastewaters.

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Electrogeneration of hydrogen peroxide (H 2 O 2) 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 H 2 O 2 electrogeneration. In the present study, we investigated the properties of ZrO 2 nanoparticles supported on carbon black (Printex L6) as electrocatalyst for H 2 O 2 production in acidic medium. The catalytic activity of ZrO 2 /C for oxygen reduction to H 2 O 2 is higher than the catalytic activity of treated carbon black. The highest selectivity of the ZrO 2 /C catalyst for H 2 O 2 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 H 2 O 2 electrogeneration, which is shown as a high current efficiency (I(H 2 O 2)%). In fact, increased H 2 O 2 yields from 74.5 to 84.2% were observed for the treated carbon black and ZrO 2 /C catalysts, respectively, whereas the I(H 2 O 2)% for the unmodified carbon black was 65.3%. Furthermore, the modification of carbon by ZrO 2 nanoparticles shifted the ORR half-wave potential towards ca. 137 mV, indicating lower energy consumption for producing H 2 O 2. Thus, the ZrO 2 /C nanoparticles are shown to be promising electrocatalysts for environmental applications.