Significantly enhanced Fenton-based oxidation processes with CuS-Cu9S8 as co-catalyst by accelerating the Fe3+/Fe2+cycles

[Display omitted] •CuS-Cu9S8 micro-flower was applied to Fenton system as co-catalyst.•CuS-Cu9S8 has positive influence on the degradation of organic pollutions.•Cu+/Cu2+ redox pairs in the CuS-Cu9S8 accelerated the Fe2+/Fe3+ conversion cycle. The co-catalyst plays an important role for improving the catalysis efficiency in Fenton system. In this paper, a new co-catalyst, CuS-Cu9S8 micro-flower was successfully prepared by a facilely hydrothermal method. The effect of co-catalysis for CuS-Cu9S8 micro-flower was evaluated by degradation of Rhodamine B (RhB) in Fenton system, and the RhB solution could be degraded 90% in 15 min in the CuS-Cu9S8 co-catalytic Fenton system under optimal condition, which is apparently better than that of the conventional Fenton system (59%). And EPR result shows that the unsaturated S atoms on the surface of CuS-Cu9S8 can capture protons to form H2S and expose more Cu+/Cu2+ active sites on the surface of CuS-Cu9S8 flower. The high co-catalytic activity of CuS-Cu9S8 on pollutant degradation can be attributed to the acceleration for the rate-limiting Fe2+/Fe3+conversion by the exposed Cu+ /Cu2+ redox pairs. The cycle experiments show that CuS-Cu9S8 has excellent chemical stability and reusability.