Regulating localized state electron and ordered electron transfer in Cu2Se using Indium element for efficient heterogeneous Fenton-like process

Local electron density at the reaction center atoms is closely related to the H2O2 activation performance of a heterogeneous Fenton -like catalyst. However, the random electron transfer often restricts the oriented electron delivery to the active center. In this study, we proposed that only efficient electrons and their ordered transfer were desirable to boost Cu(II)/Cu(I) cycle for H2O2 activation based on regulation of local electron density and electron transfer efficiency of Cu atoms in Cu2Se. Experimental results and density function theory (DFT) calculation proved that Indium atom can drive electrons to accumulate on Cu active center and provide an efficient electron transfer pathway in CuInSe2 (from Se -* Cu to In -* Se -* Cu). Hence, compared with Cu2Se, more reductive electrons can participate in the H2O2 activation process for CuInSe2, which resulted in much more efficient ofloxacin (OFX) degradation with a TOC removal rate up to 71.5 %. The electron exchange capacity of CuInSe2 was further regulated by changing the atomic ratios of Cu and In elements including CuInSe2, Cu1.5In0.5Se2 and Cu1.75In0.25Se2. CuInSe2 had the lowest electron exchange capacity and exhibited the highest reaction activity with a radical transformation efficiency from H2O2 of 9.83 x 10-4, in contrast, the value for Cu1.75In0.25Se2 was 2.78 x 10-4. We provided a new insight for improving the heterogeneous Fenton catalytic performance.