Enhanced photocatalytic degradation of ciprofloxacin by modulating charge carrier transfer at the heterointerface of cyano-modified carbon nitride/boron nitride

The regulation of photoexcited charge carrier transfer behavior can substantially enhancing the photocatalytic performance of materials. In this study, a heterojunction photocatalyst, featuring cyano-modified carbon nitride tubes (Cy-CNT) and boron nitride (BN) nanosheets, was synthesized using a thermal condensation method. Characterization results and theoretical calculations revealed that the presence of cyano groups and unique C–N–B bonds in Cy-CNT/BN endowed it with excellent photocatalytic performance. The cyano modification induced the redistribution of charge density within the molecule and resulted in the formation of a locally uneven electronic configuration, which attenuated photogenerated electron-hole pair recombination. As an electron transfer bridge, the C–N–B bond established an interfacial transfer channel to promote electron migration and electron-hole pair separation. Consequently, the production of •O 2 − and 1 O 2 by Cy-CNT/BN was substantially enhanced by factors of 7.7 and 1.5, respectively, compared with those generated by the pristine carbon nitride tube (CNT). Ciprofloxacin was thus efficiently degraded by Cy-CNT/BN, and the kinetic constant (0.034 min −1 ) was 2.7 and 1.6 times that of CNT and Cy-CNT, respectively. Meanwhile, a floating photocatalyst was prepared by loading Cy-CNT/BN on polyurethane sponge, and the results indicated that this floating photocatalyst had good practicality in the remediation of antibiotic-contaminated surface water. The life cycle assessment results showed that, compared with CNT and Cy-CNT, Cy-CNT/BN exhibited minimum environmental impacts and had a reduced environmental burden. This paper presents a new strategy for charge carrier regulation of carbon nitride-based photocatalysts, which may promote the development of antibiotic-contaminated water remediation technology.