Sustainable microwave-assisted hydrothermal synthesis of carbon-supported ZrO2 nanoparticles for H2O2 electrogeneration

Highlights: • Carbon-based metal oxide catalyst was produced by sustainable MAH approach. • ZrO₂-5.1 wt% on PL6C presented a gain of 140 mV in E_1/2 and S_H2O2 of 88.8%. • Particles dispersion, ECSA, and oxide loading are key elements to consider in ORR. • ZrO₂/PL6C presented k_app values for H₂O₂ production ~2x higher than bare PL6C. This work proposes the use of a novel green and fast (2O₂ electrogeneration. Using ZrO₂ supported on carbon black Printex L6 (PL6C) as a non-toxic model catalyst, the present study evaluated different synthesis conditions and their effects on ORR activity and selectivity via the application of the rotating ring-disk electrode (RRDE) and gas diffusion electrode (GDE) techniques. RRDE results showed that the optimized ZrO₂/PL6C catalyst presented improvements in catalytic performance of 140 mV in the E_1/2 for ORR and in selectivity for H₂O₂ production of 88.8% compared to the unmodified PL6C (78%). The improved electrocatalytic performance was attributed to the high dispersion of small ZrO₂ nanoparticles (~7 nm) in direct contact with the carbon support which helped increase the ECSA values. GDE results showed that ZrO₂/PL6C was responsible for doubling the k_app values of H₂O₂ production and for the reduction of energy consumption by about 150 kWh g⁻¹ compared to the unmodified matrix. Key insights related to the construction of carbon-based metal oxide catalysts and the optimization of ORR are discussed further in the work aiming at providing useful contributions for future investigations and applications.