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

This work proposes the use of a novel green and fast (<1h) route for the construction of electrocatalysts by microwave-assisted hydrothermal synthesis using carbon-supported metal oxide for H2O2 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 E1/2 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 kapp 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. © 2021 Elsevier B.V.