Conductive polypyrrole encapsulating Cd0.5Zn0.5S to enhance hydrophilicity and charge separation towards robust photodegradation of tetracycline hydrochloride and photoreduction of Cr (VI)

Abstract

To effectively promote the charge transfer by using the synergistic effect between different materials is a compelling avenue for solving unsatisfactory photocatalytic efficiency of single photocatalyst. Herein, a layer of conducting polymer polypyrrole (PPy) was first applied to cover on the surface of Cd0.5Zn0.5S nanoparticle for constructing a novel polymer-inorganic PPy/Cd0.5Zn0.5S heterostructure (PPy/CZS) by in-situ oxidative polymerization. The as-prepared PPy/CZS heterostructure exhibited much fast and superior photocatalytic performances for the photocatalytic oxidation of harmful antibiotic-pollutant tetracycline hydrochloride (TCH) and reduction of toxic heavy metal ion Cr (VI) compared to single Cd0.5Zn0.5S. The optimized 10PPy/CZS sample presented the highest photoreduction rate of Cr (VI) with 100% in 30 min and the photodegradation efficiency of TCH was 87.4% within 25 min, respectively. The apparent rate constants of TCH photodegradation (0.0729 min−1) and Cr (VI) photoreduction (0.1330 min−1) over 10PPy/CZS were 5.41 and 2.62 times more than those of the pure Cd0.5Zn0.5S (0.0135 and 0.0506 min−1), respectively. The designed 10PPy/CZS heterojunction with intimate contact interfaces could not only efficiently increase the surface area, the superficial high-hydrophilicity and the visible-light responsive ability, but also accelerate the transferring and separation of photo-induced charge pairs, resulting in the striking photocatalytic activity. Furthermore, a possible photodegradation pathway of TCH and photoreaction mechanism were also presented in depth. This present work would provide a viable avenue to design fast and efficient Cd0.5Zn0.5S based photocatalysts for solving the environment issues.