Enhanced activation of H2O2 by bimetallic Cu2SnS3: A new insight for Cu (II)/Cu (I) redox cycle promotion

Despite that the development of Cu2SnS3 (CTS) catalyst has attracted increasing interests, few study has reported to investigate its heterogeneous catalytic degradation of organic pollutants in a Fenton-like process. Furthermore, the influence of Sn components towards Cu (II)/Cu (I) redox cycling in CTS catalytic systems remains a fascinating research.In this work, a series of CTS catalysts with controlled crystalline phases were prepared via a microwave-assisted pathway and applied in the H2O2 activation for phenol degradation. The efficiency of phenol degradation in CTS-1/H2O2 system (CTS-1: the molar ratio of Sn (copper acetate) and Cu (tin dichloride) is determined to be Sn:Cu = 1:1) was systematically investigated by controlling various reaction parameters including H2O2 dosage, initial pH and reaction temperature. We discovered that Cu2SnS3 exhibited superior catalytic activity to the contrast monometallic Cu or Sn sulfides and Cu (I) acted as the dominant active sites. The higher Cu (I) proportions conduce to the higher catalytic activities of CTS catalysts. Quenching experiments and electron paramagnetic resonance (EPR) further proved that the activation of H2O2 by CTS catalyst produces reactive oxygen species (ROS) and subsequently leads to degradation of the contaminants. A reasonable mechanism of enhanced H2O2 activation in Fenton-like reaction of CTS/H2O2 system was proposed for phenol degradation by investigating the roles of copper, tin and sulfur species.The developed CTS acted as a promising catalyst in Fenton-like oxidation progress for phenol degradation. Importantly, the copper and tin species contribute to a synergetic effect for the promotion of Cu (II)/Cu (I) redox cycle, which thus enhanced the activation of H2O2. Our work may offer new insight on the facilitation of Cu (II)/Cu (I) redox cycle in Cu-based Fenton-like catalytic systems.