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

Abstract 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.