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/CeO₂ nanocomposites were synthesized by a simple hydrothermal process, and the effect of different Cu/Ce molar ratios was explored. p‐CuO/n‐CeO₂ was found to exhibit higher conductivity and electrocatalytic activity toward the target superoxide anion (O₂^.−) when compared to both bare CuO and CeO₂. Characterization shows that different Cu/Ce ratios in p‐CuO/n‐CeO₂ materials result in a considerable variation in the Ce³⁺/Ce⁴⁺ level, and energy band gap of CeO₂, greatly affecting the electrochemical performance of p‐CuO/n‐CeO₂. Under optimized conditions, these sensors exhibit high sensitivity and low detection limit toward O₂^.−. These results demonstrate that the performance of semiconductor‐based electrochemical sensors may be enhanced by the electron‐transfer process of p‐n junction interfaces.