A core-shell confinement strategy towards single-atom Fe-N/S-C bifunctional catalyst for selective nitroarene reduction and olefin epoxidation

Heteroatom doping provides an effective approach to regulating the catalytic properties of single-atom catalysts for chemical reactions. However, the economical and controllable production of efficient single-atom catalysts with tailored coordination structures presents a formidable challenge. In this study, we demonstrate a novel core-shell confinement strategy to fabricate a single-atom iron catalyst on carbon nanoshells (Fe-N/S-C) for the bifunctional selective reduction of nitroarenes and epoxidation of olefins. Through the encapsulation of polydopamine-coated nano-Fe 2 O 3 within sulfur-rich petroleum asphalt, atomically dispersed Fe-N 3 S 1 with asymmetric coordination were meticulously engineered through one-step thermal treatment, obviating the need for additional sources of iron, nitrogen, or sulfur. Under mild reaction conditions, the Fe-N/S-C catalyst achieved a complete conversion of p-nitrophenol with over 99 % selectivity and a high overall turnover frequency (TOF) of 116.9 h −1 . Meanwhile, the Fe-N/S-C catalyst could also accomplish an 80.2 % conversion in the epoxidation of styrene with a high selectivity of 93.6 %. The remarkable catalytic activities, as well as exceptional stability, notably surpass those of reported single-atom Fe-N-C and noble metal catalysts. Experimental results and theoretical calculations indicate that the negative charge induced by sulfur doping efficiently modulates the electron distribution of the active center and enhances the adsorption/desorption and activation of the reaction substrates, thereby accelerating the catalytic processes involved in selective reduction and oxidation. This work offers a promising approach to the development of cost-effective and potent catalysts for chemical transformations.