Samarium-Doped PbO2 Electrocatalysts for Environmental and Energy Applications: Theoretical Insight into the Mechanisms of Action Underlying Their Carbendazim Degradation and OER Properties

Abstract

This study presents the fabrication of a samarium-doped Ti/Sb-SnO<inf>2</inf>/PbO<inf>2</inf> electrode and investigates its applications in polluted water treatment and energy conversion. Physicochemical properties were characterized by scanning electron microscopy with energy-dispersive X-ray spectroscopy, X-ray powder diffraction analysis, and Raman spectroscopy. The Ti/Sb-SnO<inf>2</inf>/Sm-PbO<inf>2</inf> electrode showed 2.5 times higher oxygen evolution potential activity than the Ti/Sb-SnO<inf>2</inf>/PbO<inf>2</inf> electrode. Density Functional Theory was used to conduct first-principles calculations, and the obtained results indicated that Sm doping enhances the production of reactive oxygen species. The application of the Ti/Sb-SnO<inf>2</inf>/Sm-PbO<inf>2</inf> electrode in carbendazim (CBZ) removal was investigated, since CBZ is a fungicide whose presence in the environment, including food, water, and soil, poses a threat. After 60 min of the treatment under optimized working parameters, the degradation rate of CBZ reached 94.2% in the presence of 7.2 g/L Na<inf>2</inf>SO<inf>4</inf> with an applied current density of 10 mA/cm² in an acidic medium (pH 4). Of the four investigated parameters, the current density had the most significant influence on the degradation process. At the same time, the initial pH value of the solution was shown to have the least impact on degradation efficiency. These results imply a potential use of the proposed treatment for CBZ removal from wastewater.