Directional electron transfer in single-atom cobalt nanozyme for enhanced photo-Fenton-like reaction

In this study, enzyme-mimicking single-atom (EMSA) catalyst was fabricated by implanting cobalamin cofactor-resembling Co-N4 sites into graphite carbon nitride (g-C3N4). The EMSA-Co sites inherit the high catalytic activity and selectivity from natural enzymes and demonstrate outstanding performance for persulfate (PS) activation under visible light (Vis). The kinetic rate constant for BPA degradation in the EMSA-Co-g-C3N4 +PS+Vis system was about 33 times faster than that in the g-C3N4+PS+Vis system. The benefits of high reactivity and selectivity of the EMSA-Co sites led to efficient generation of the radical species (SO4•−, •OH and O2•–), resulting in the fast elimination of various organic pollutants. Mechanisms studies reveal that the directional ultrafast electron transfer in the EMSA-Co nanozyme leads to an accelerated redox circulation of the Co single sites, thereby boosting their performance for photo-Fenton-like reaction. This study opens up the avenue of robust and efficient enzyme-like SACs for applications in environmental remediation.