Simultaneous growth strategy for constructing a Cu–Fe/carboxylate-decorated carbon composite with improved interface compatibility and charge transfer to boost the visible photocatalytic degradation of tetracycline

Abstract

Developing efficient photocatalysts for the oxidative degradation of recalcitrant pharmaceutical pollutants is significant and challenging. In this study, a simultaneous growth strategy was proposed to construct an interpenetrating-structured Cu–Fe/carboxylate-decorated carbon (CDC) composite by the one-pot hydrothermal carbonization of a mechanical activation (MA)-treated precursor (starch, FeCl3, and CuCl2) in the presence of a carboxylate. The as-prepared MA-Cu–Fe/CDC composite was used as a highly active photocatalyst for effectively degrading tetracycline (TC), owing to the columnar-structured Cu–Fe-based components, improved interface compatibility, and increased oxygen vacancy concentration. This promoted the utilization efficiency of visible light, charge transfer, and separation of photoinduced holes–electrons, thus effectively boosting the photocatalytic activity. As abundant active radicals were generated by MA-Cu–Fe/CDC under visible light irradiation, 100% of TC was removed after 50 min (kinetic rate constant of 0.092 min−1), and a mineralization ratio of 85.4% was achieved after 180 min. The photocatalytic degradation of TC was a gradual detoxification process. Moreover, MA-Cu–Fe/CDC maintained good photocatalytic activity after five cycles (TC removal of 98.9%), with almost no change in the surface chemical structure and a low leaching rate of metal ions owing to its excellent structural stability. This efficient and stable visible light-driven photocatalyst can potentially be used for constructing a photocatalytic degradation system for the sustainable and energy-conserving treatment of organic contaminants.