Enzyme-free photoelectrochemical sensing of glucose based on the TiO2/CuO heterojunction

Conventional enzyme-based glucose sensors have good selectivity and sensing performance, but the disadvantages of the enzyme itself (enzyme activity is susceptible to pH and temperature) lead to a limited number of uses and result in high costs. Therefore, photoelectrochemical enzyme-free glucose sensors have attracted research interest in recent years. In this work, the TiO2/CuO heterojunction was constructed and photoelectrochemical enzyme-free glucose sensing was realized. The sensing sensitivity of the TiO2/CuO heterojunction photoelectrode prepared by magnetron sputtering and thermal annealing process was 864 μAμM-1 cm-2 in the range of 1–9 mM with a detection limit of 58.6 μM at 0.2 V, exhibiting satisfactory stability as well as interference resistance. This better sensing performance mainly comes from: 1) the absorption of photogenerated carriers generated from sunlight by TiO2 films, which participate in glucose redox; 2) the conversion of the metal valence state (Cu2+/Cu3+) of the P-type semiconductor CuO under alkaline conditions can promote glucose redox; 3) the heterojunction formed by CuO and TiO2 reducing the compounding of photogenerated carriers thus improving the photoelectric conversion efficiency. The heterojunction formed by CuO and TiO2 greatly facilitates the surface carrier transfer of glucose oxidation reaction. This work provides a new way for enzyme-free glucose sensing and promotes the development of glucose detection technology.