Synergy of Fenton-like property and self-oxygen supply for realizing enhanced near-infrared-driven integrated wastewater treatment

Near-infrared-driven photocatalysis represents the maximized utilization of solar energy and how to enhance its activity is of great significance. To achieve this, we design a synergetic composite of SnFe2O4@CaO2 in this work. CaO2 layer could react with H2O to generate H2O2 and O-2. Then, SnFe2O4 could trigger Fenton-like reaction to convert H2O2 to (OH)-O-center dot and O-center dot(2) (-) for the pollutant degradation, which is a similar process to the advanced oxidation process. Additionally, SnFe2O4 is a NIR-responsive photocatalyst, which could convert dissolved oxygen into reactive oxygen species (ROS) under irradiation. Thus, the synergetic action between CaO2 and SnFe2O4 gives a better catalytic outcome. The experimental results demonstrate that (OH)-O-center dot and O-center dot(2) (-) are the main free radicals of the reaction. The kinetics characteristics of the free radicals generation are examined and a possible photocatalysis degradation mechanism is proposed. Moreover, the SnFe2O4@CaO2 exhibits excellent photocatalytic sterilization performance. Therefore, the SnFe2O4@CaO2 achieved integrated treatment of wastewater.