Photoelectrochemical sensor based on Sn3O4/CdS heterojunction for detecting glucose in the body and Cu(Ⅱ) ion

In this work, photoactive composites of Sn3O4/CdS at different ratios were synthesized by a solvothermal method. First, Sn3O4 was synthesized. To further improve its photoelectric performance, Sn3O4/CdS-X(X = n(Sn3O4)/n(CdS)) with different molar ratios were synthesized by solvothermal method. The composition, surface structure, valence state and optical properties of Sn3O4/CdS-X were studied by a series of characterization methods. The test results show that Sn3O4/CdS-X have better photoelectric performance than Sn3O4 and CdS. UV–visible diffuse reflectance spectroscopy (UV–vis DRS) and photoluminescence (PL) demonstrate Sn3O4/CdS-0.55 exhibits the broadest visible light absorption range (360 ∼ 540 nm) and the strongest ability of photogenerated carrier separation. Based on the above performance advantages, Sn3O4/CdS-0.55 was opted to construct the PEC sensor for glucose and Cu(Ⅱ) ion. The linear range for detecting glucose is 0.5 µM-40 mM, and the LOD is 0.067 µM (S/N = 3). For Cu(Ⅱ) ion, these values are 1–290 µM and 0.066 µM, respectively. Moreover, the sensor shows superior selectivity, stability, and reproducibility, which can be used to detect actual samples.