Low‐Temperature Pyrolysis: A Universal Route to High‐Loading Single‐Atom Catalysts for Fuel Cells

Abstract High‐temperature pyrolysis (HTP, ≥900 °C) is a widely used method for synthesizing single‐atom catalysts (SACs). However, the high operational temperatures required for HTP pose significant challenges in achieving high single‐atom loading, primarily due to the Ostwald ripening effect. In this work, a low‐temperature trans‐metalation synthesis approach is developed which involves the exchange of cation between transition metal ions (M = Fe, Co, Cu, Ni, Mn, etc) and Zn ²⁺ ions on a nitrogen‐doped carbon (NC) matrix within a molten salt medium. This strategy effectively avoids phase transformations and enables the direct formation of high mass loading (3.7–4.7 wt.%) of atomically dispersed M‐N ₄ sites. Both experimental and theoretical analyses confirm that this cation‐exchange occurs at a lower temperature threshold of 450 °C, significantly reducing the energy barriers for SACs synthesis. Furthermore, the synthesized catalyst with atomically dispersed Fe sites demonstrate excellent performance toward oxygen reduction reaction and fuel cell with a peak power density of 1.12 W cm ⁻² in an H ₂ ─O ₂ fuel cell at 1.0 bar and 80 °C.