Multivalent copper-carbon-catalyzed persulfate/O2 system: The relation between copper valence and the species of reactive oxygen

Modulation of nano electrocatalysts for targeted excitation of different reactive oxygen species (ROS) is a key challenge to achieve environmentally catalyzed efficient pollutant degradation. In this study, multivalent copper catalysts (Cu (0)/Cu (I)/Cu (II)) load on the surface of biochar (CBX) are prepared by the hydrothermal-impregnation method, and the modulation effect of different valences of copper on the pathway of reactive oxygen species (ROS) generation is investigated. X-ray diffraction (XRD) analysis shows the coexistence of three copper valence states. Radical scavenging experiment and DFT calculations indicate that Cu (I) dominates the adsorption and activation of peroxodisulfate (PS) to efficiently generate ·SO 4 - and ·OH. Cu (II) selectively generates 1 O 2 by modulating the dissolve oxygen conversion pathway; whereas Cu (0) acts as an activation center for bound oxygen and significantly promotes ·O 2 - generation. The nano-electrocatalytic system prepared at 600°C (CB6-PS) degraded 98.3% of enrofloxacin (ENR) over a period of time (60   min). Mechanistic studies indicate that the catalytic system realizes the coupling reaction between the radical pathway (·SO 4 - /·OH /·O 2 - ) and the nonradical pathway ( 1 O 2 ) by the synergistic action of multivalent copper, which providing a new theoretical basis and technical strategy for the development of targeted ROS generation function.