Engineering the doping amount of rare earth element erbium in CdWO4: Influence on the electrochemical performance and the application to the electrochemical detection of bisphenol A

Rare earth elements Er doped CdWO4 (Er-CdWO4) nanorods were successfully prepared. The morphology, crystal structure, chemical environments and electrochemical properties of Er-CdWO4 nanomaterials were regulated by changing the doping amount of Er. Scanning electron microscope (SEM) and transmission electron microscopy (TEM) have shown that the introduction of moderate content of Er could optimize the morphology of CdWO4. X-ray diffraction (XRD) results suggested that the larger Er ions partially replaced the Cd ions in CdWO4 nanocrystals and produced favorable lattice gaps and defects around the unit cell. The high-resolution X-ray photoelectron spectroscopy (XPS) of O 1 s and the enhanced peak intensity in electron spin resonance (EPR) declared that the doping of Er generated more oxygen vacancies in Er-CdWO4. Based on the physico-chemical characterizations, 0.5 wt% Er-CdWO4 was confirmed to be the best electrocatalyst within the tested samples, which exhibited the fastest electron transfer performance and the strongest electrocatalytic capacity to BPA. Taking the low-cost and simply prepared Er-CdWO4 with the optimal content of Er as the electrode modifier, a novel electrochemical sensor (Er-CdWO4/CPE) for BPA has been constructed for the first time, which exhibited the wide linear ranges from 0.01 to 6 μM and the limit of detection of 0.003 μM, respectively. Moreover, satisfactory reproducibility, stability and anti-interference performance were also achieved on Er-CdWO4/CPE. Meanwhile, the proposed sensor successfully realized the determination of BPA spiked in local tap water samples.