High-loaded single-atom Cu-N3 sites catalyze hydrogen peroxide decomposition to selectively induce singlet oxygen production for wastewater purification

Single-atom catalysts (SACs) have been widely used in Fenton-like water treatment, but studies on the selective induction of H2O2 to produce singlet oxygen (1O2) are rare. Herein, a carbon nitride supported high-loaded single-atom Cu-N3 catalyst (Cu-CN, Cu load is 15.46 wt%) is prepared to activate H2O2 to selectively form 1O2. Experimental and DFT calculation results reveal that the key factor for 1O2 production is the Cu-N3 coordination structure. Specifically, Cu-N3 coordination structure is conducive to decomposing H2O2 into·OOH/·O2-. Besides, the density of Cu-N3 sites is another key factor, high Cu-N3 site density is conducive to the rapid conversion of·OOH/·O2- to 1O2. Benefitting from the dominant role of 1O2, the Fenton-like degradation performance of Cu-CN/ H2O2 system is not disturbed under high salinity conditions, and the performance is significantly enhanced at high pH. This work represents an important reference in understanding SACs for activated H2O2 to generate 1O2.