Photo-electrochemical sensor based on MoO3/ZnCdS Z-type heterojunction for detecting 4-Nitrophenol and hexavalent chromium

In this study, firstly, ZnxCd1−xS (x = 0.7, 0.5, 0.3) was synthesized. The results from testing show the photocurrent response of Zn0.3Cd0.7S is better than the other two materials. In order to improve PEC performance, different molar amount of MoO3 was introduced to synthesize composites MoO3/Zn0.3Cd0.7S-Y (Y=0.10、0.20、0.25、0.30、0.40). It is found that the properties of the composites are better than MoO3 and Zn0.3Cd0.7S. Furthermore, the results from UV–visible diffuse reflectance spectroscopy (UV–vis DRS) and photoluminescence (PL) indicate MoO3/Zn0.3Cd0.7S-0.3 has the widest visible light absorption range and the most powerful photogenerated carrier separation capability in all samples. On the basis of analysis, a PEC sensor based on MoO3/Zn0.3Cd0.7S-0.3 was constructed to detect 4-Nitrophenol (4-NP) and hexvalent chromium (Cr (VI)). The linear range of 4-NP sensor is 0.05–100 μM, LOD is 0.028 μM (S/N = 3). For Cr (VI), these values are 0.1–240 μM and 0.019 μM, respectively. Simultaneously, the sensor has positive stability, reproducibility and selectivity, and can be utilized in actual samples. Hence, the PEC sensor based on MoO3/Zn0.3Cd0.7S-0.3 will have a promising application to detect 4-NP and Cr (VI).