Efficient degradation of tetracycline residues in pharmaceutical wastewater by Ni/Fe bimetallic atomic cluster composite catalysts with enhanced electron transfer pathway

Metal cluster catalysts have large atomic load, interaction between atomic sites, and wide application of catalysis. In this study, a Ni/Fe bimetallic cluster material was prepared by a simple hydrothermal method and used as an efficient catalyst to activate the degradation system of peroxymonosulfate (PMS), which showed nearly 100% tetracycline (TC) degradation performance over a wide pH range (pH = 3-11). The results of electron paramagnetic resonance test, quenching experiment and density functional theory (DFT) calculation show that the non-free radical pathway electron transfer efficiency of the catalytic system is effectively improved, and a large number of PMS are captured and activated by high density Ni atomic clusters in Ni/Fe bimetallic clusters. The degradation intermediates identified by LC/MS showed that TC was efficiently degraded into small molecules. In addition, the Ni/Fe bimetallic cluster/PMS system has excellent efficiency for degrading various organic pollutants and practical pharmaceutical wastewater. This work opens up a new way for metal atom cluster catalysts to efficiently catalyze the degradation of organic pollutants in PMS systems.