Unveiling the intrinsic electrochemical mechanism of supporting electrolyte and the interaction mechanism in electrochemical oxidation of tetracycline with nano-PbO2†

Abstract

Electrochemical oxidation (EO) for the removal of antibiotics is a promising technique because of the green and sustainable electrical-to-chemical energy conversion. However, the interaction mechanism between different electrolyte molecules and organic pollutants along with the generation pathway of reactive oxygen species remains unclear. Here, a β-PbO₂ electrode was successfully prepared and employed as an effective tool for organic pollutant removal. The EO process with the β-PbO₂ electrode and Na₂SO₄ electrolyte could completely remove tetracycline (TC) and achieve an impressive kinetic rate constant of 0.239 min⁻¹. Quantum chemical calculations confirmed that hydrogen bonding was the primary binding force between TC and Na₂SO₄. Density functional theory calculations emphasized the key roles of radical and non-radical pathways in TC removal via the key reaction site (O atom in PbO₂). Consequently, this study provided a novel insight into the intrinsic electrochemical behavior changes with various electrolytes, paving the way for a novel electrochemical process in water treatment applications.