Dual‐Shelled Hollow Leafy Carbon Support with Atomically Dispersed (N,S)‐Bridged Hydroxy‐Coordinated Asymmetric Fe Sites for Oxygen Reduction

Abstract Single‐atom catalysts (SACs) are widely studied in various chemical transformations due to their high catalytic activity and atom utilization. However, modulating the catalytic performance of catalysts by adjusting the microenvironment remains a great challenge. In this paper, a novel master‐double guest vulcanization‐assisted strategy is reported for synthesizing Fe single‐atom catalysts on N,S codoped porous hollow leaf carbon (Fe_SA/N,S‐PHLC) with highly exposed FeN₃SOH sites. Fe(mIm) (guest I) is loaded on the surface of ZIF‐L (host) and then trithiocyanuric acid (TCA, guest II) is bonded with Fe(mIm), and the resulting ZIF‐L@Fe(mIm)@TCA precursors can be converted to Fe_SA/N,S‐PHLC with controllable structures. In addition, XPS analysis yield an increase in pyridine N content in Fe_SA/N,S‐PHLC compared to Fe_SA/N‐PHLC. It can be demonstrated by theoretical calculations that the N,S‐coordinated axially hydroxy‐coordinated asymmetric Fe centers synergistically with the abundance of pyridinic nitrogen facilitate the adsorption and desorption of oxygen intermediates, and the 3d orbitals of the Fe active centers can be optimized. The prepared Fe_SA/N,S‐PHLC catalyst has a half‐wave potential (E_1/2) of 0.91 V under alkaline conditions, and E_1/2 = 0.75 V under acidic conditions. It shows excellent cycle stability (882 h) and power density (217 mW cm⁻²) in the assembly of zinc–air battery (ZABs) devices.