Enhanced electron transfer kinetics via constructing co-catalytic system of cerium oxide and carbon dots enabling efficient electrosynthesis of hydrogen peroxide in neutral media

Abstract

The sluggish kinetics coupled with the competition of four-electron pathway in neutral media diminishes the production efficiency of hydrogen peroxide (H2O2) via the two-electron oxygen reduction reaction (2e− ORR). To address this dilemma, this contribution proposes one electron modulation strategy to expedite the charge transfer capability by integrating carbon dots with CeO2 (CDs/CeO2) for the efficient neutral electrosynthesis of H2O2. It was found that the integration could effectively bolster both the activity and selectivity of 2e− ORR on CDs and CeO2. Remarkably, the highest 2e− selectivity could reach up to 92 % for the optimized CDs/CeO2, substantially surpassing that (77 %) of pristine CeO2, together with about 1.5 times enhancement of activity. Meanwhile, it also delivered a superior long durability at 20 mA cm−2 for 24 h and a high Faraday efficiency of 97 %. Further in-situ transient potential scanning (TPS) technique revealed that the pseudo-capacitance and charge storage capacity of CeO2 were significantly tuned by CDs during dynamic ORR process, being conducive to the reaction kinetics and the 2e− selectivity. The findings in this work not only extends the co-catalytic system based on CDs and rare earth materials for 2e− ORR, but also offers novel insights into correlation between their electron distribution dynamics and 2e− ORR performance.