Efficient electrocatalytic degradation of tigecycline by copper foam-supported Pd-ZnS dual nanoparticle structures: A study of H* reduction and mechanism of action

Abstract

Tigecycline (TGC), a third-generation, broad-spectrum, potent antimicrobial drug based on a tetracycline structure, may pose potential hazards to ecosystems and human health due to its difficulty in natural degradation in the environment. However, the environmental degradation behavior of TGC has not been fully investigated, so it is still a major challenge to rationally design efficient, stable, environmentally friendly and cost-effective electrocatalysts for TGC degradation. In this study, Pd-ZnS NPs/CF composite electrode anchored on copper foam (CF) was synthesized by simple ultrasonic method and two-step electrodeposition. The degradation efficiency of TGC at the Pd-ZnS NPs/CF composite electrode was as high as 88.75 % within 30 min under neutral conditions, and the energy consumption was only 0.11 kWh/m³ . In addition, the overall Pd²⁺ contribution was as low as 0.00005 M after the introduction of inexpensive ZnS. The Pd-ZnS NPs/CF composite electrode exhibited excellent electrocatalytic activity and degradation of antibiotics under different aqueous environmental conditions. Suitable for degradation of a wide range of antibiotics with excellent cyclic stability. The TGC degradation rate was stabilized above 85.40 % after 240 min of continuous operation in a continuous flow reactor, and the composite electrode prepared once can be used for a long time. It highlights the broad application prospects of the composite electrode in the field of water treatment technology and the significant advantages of high efficiency, low energy consumption and stable long-term operation. In this study, the mechanism of action of ·OH and H* with TGC is also deeply investigated, and the dynamics of TGC degradation intermediates are probed using two-dimensional correlation spectroscopy (2DCOS) and density-functional theory (DFT) calculations. Finally, the ecotoxicity of Pd-ZnS NPs/CF composite electrodes is investigated, which provides a simple and feasible idea for the preparation of efficiently degraded antibiotic cathodes.