New Photocathodic Analysis Platform with Quasi-Core/Shell-Structured TiO₂@Cu₂O for Sensitive Detection of H₂O₂ Release from Living Cells

In this work, we clearly demonstrate for the first time the use of a p-type semiconductor, Cu₂O, as the core unit of a photocathode to set up a new photocathodic analysis platform. With the help of a facile protection strategy, the Cu₂O photocathode presented efficient photoelectrochemical performance for H₂O₂ sensing with a detection limit of 0.15 μM, which allowed the new photocathodic analysis platform to detect H₂O₂ released from living tumorigenic cells, thus demonstrating its potential application as a sensitive cancer detection probe. The protected TiO₂ layer was coated on Cu₂O to form a quasi-core/shell structure (TiO₂@Cu₂O) through a facile sol-gel method, which significantly enhanced the photostability, comparable to the TiO₂@Cu₂O samples prepared by a complicated atomic layer deposition method. In this new photocathodic analysis platform, the semiconductive metal oxides accomplish a job usually completed by conductive noble metals in an electroanalysis process. We believe that this photocathodic detection strategy opens up a new detection approach, extends the application range of semiconductor materials, and thus sheds light on the further fusing of photoelectrochemical technique with analytical methods.