The construction of p–n heterojunctions instead of p-type or n-type semiconductors can improve the separation efficiency of photoinduced electrons and holes. In this work, BiOI/tetrapod-like ZnO whisker (T-ZnOw) p–n heterojunction photocatalysts with different Bi/Zn molar ratios were prepared by the in situ precipitation of BiOI on a T-ZnOw substrate. The BiOI/T-ZnOw photocatalysts efficiently degraded rhodamine B (RhB) and oxytetracycline (OTC) under visible light irradiation. The photocatalyst with a Bi/Zn molar ratio of 1 : 10 (BZ-10) exhibited the highest photocatalytic activity, with 97.1% and 88.0% removal of RhB and OTC, respectively. After degradation cycling experiments, the OTC removal efficiency was still 80.7%. The photocatalytic activity of the BZ-10 composite was improved compared to those of pure T-ZnOw and BiOI. This was attributed to the large specific surface area and the efficient separation of charge carriers caused by the formation of p–n heterojunctions between BiOI and T-ZnOw. The photodegradation mechanism was put forward based on radical trapping experiments and electron spin resonance (ESR) results. The synthesized BiOI/T-ZnOw heterojunction composite could be a promising photocatalyst in environmental photocatalysis.

A molecularly imprinted polymer (MIP) with 3D worm-like nanorod structures was constructed by cyclic voltammetry (CV) polymerization, using 3,4-ethylenedioxythiophene (EDOT) and pyrrole (Py) as bifunctional monomers, and rutin as the template on a glassy carbon electrode (GCE). The optimum polymerization conditions of MIP were obtained by the orthogonal test. The range analysis suggested that the potential range was the most influential factor. Compared with MIP/1.5 and MIP/1.9, the MIP films prepared in the potential range of 0–1.7 V (MIP/1.7) had better current response to rutin, faster charge transfer rate and higher doping levels by differential pulse voltammetry (DPV), Chronocoulometry and X-ray photoelectron spectroscopy (XPS) analysis. Rutin could be detected in the concentration range of 0.5 nM to 1 μ M, and 5 to 50 μ M with the low detection limit as 0.24 nM (S/N = 3). Moreover, MIP/1.7 exhibited 3-fold increase current response toward rutin by DPV when compared with the corresponding non-imprinted polymer (NIP), revealing the success of the imprinting. This sensor also exhibited high selectivity, good long-term stability, and acceptable reproducibility. The rutin content in Flos Sophorae Immaturus (FSI) was 25.37% with good accuracy.