A win-win strategy of wastewater recycling and treatment: synchronous hydrogen production and norfloxacin degradation

Abstract

It is highly desirable to efficiently produce hydrogen utilizing industry wastewater and to clean wastewater at the same time. Herein, WS2 with sulfur vacancy (Vs) is synthesized through a simple molten salt method. The WS2 samples with less and more Vs are labeled as WS2-1 and WS2-2, respectively. The results show that in a 1 M KOH solution, the oxygen evolution reaction overpotentials at 10 mA/cm2 (η10) are 306 and 220 mV for WS2-1 and WS2-2, respectively; while the overpotentials at 10 mA/cm2 (η10) of WS2-1 and WS2-2 are both 220 mV for the hydrogen evolution reaction. Besides, density functional theory calculations prove that the introduction of Vs regulates the electronic structure of WS2 and promotes the adsorptions of H2O and OH−. In addition, a higher Vs concentration can further boost the conductivity, electron density, and adsorptions of H2O and OH−. Moreover, while using the simulated norfloxacin wastewater as the electrolyte, the hydrogen evolution reaction is obviously improved by norfloxacin oxidation reaction. After operating at 1 V for 2 h, 41.6% of norfloxacin has been degraded over WS2-2 and 95.7% of current density is still retained, confirming a good stability. This work demonstrates that hydrogen production and pollutant degradation can be achieved synchronously, and this work provides a win-win strategy for wastewater recycling and treatment.