Enhanced Electrocatalytic Activity of p-CuO/n-CeO2-Heterojunction-Based Nanocomposites for Superoxide Determination: Influence of the Cu/Ce Ratio

Graphical It's super ! The p-n junction was introduced to electrochemical catalysts for superoxide detection. Based on the superoxide dismutase mimic activity of CeO 2 and the high electrochemical catalytic activity of CuO, a non-enzymatic superoxide sensor was established. Owing to the construction of a p-n heterojunction, the sensing performances of p-CuO/n-CeO 2 composites were further enhanced. This method could serve as an effective strategy to overcome the intrinsic defects of semiconductor catalysts and improve their applications in electrochemical sensors. The performance of electrochemical sensors is mainly limited by the intrinsic properties of electrocatalysts fabricated on the electrode. Introducing a p-n heterojunction into semiconducing electrocatalysts is an effective strategy to enhance the sensing performance. In this paper, p-n-heterojunction-based CuO/CeO 2 nanocomposites were synthesized by a simple hydrothermal process, and the effect of different Cu/Ce molar ratios was explored. p-CuO/n-CeO 2 was found to exhibit higher conductivity and electrocatalytic activity toward the target superoxide anion (O 2 .− ) when compared to both bare CuO and CeO 2 . Characterization shows that different Cu/Ce ratios in p-CuO/n-CeO 2 materials result in a considerable variation in the Ce 3+ /Ce 4+ level, and energy band gap of CeO 2 , greatly affecting the electrochemical performance of p-CuO/n-CeO 2 . Under optimized conditions, these sensors exhibit high sensitivity and low detection limit toward O 2 .− . These results demonstrate that the performance of semiconductor-based electrochemical sensors may be enhanced by the electron-transfer process of p-n junction interfaces.