Molten salt as ultrastrong polar solvent enables the most straightforward pyrolysis towards highly efficient and stable single-atom electrocatalyst

Abstract

Abstract Currently, pyrolysis as the most widely used method still has some key issues not well resolved for synthesis of carbon-supported single-atom catalysts (C-SACs), e.g., the sintering of metal atoms at high temperature as well as the high cost and complicated preparations of precursors. In this report, molten salts are demonstrated to be marvellous medium for preparation of C-SACs by pyrolysis of small molecular precursors (ionic liquid). The ultrastrong polarity on one hand establishes robust interaction with precursor and enables better carbonization, resulting in largely enhanced yield. On the other hand, the aggregation of metal atoms is effectively refrained while no nanoparticle or cluster is formed. By this strategy, a C-SAC with atomically dispersed Fe-N4 sites and a high specific area over 2000 m2 g−1 is obtained, which illustrates high ORR activity in both acid and alkaline media. Moreover, this SAC exhibits superior methanol tolerance and stability after acid soaking at 85 °C for 48 h. It is believed that the molten-salts-assisted pyrolysis can be developed into a routine strategy as it not only can largely simply the synthesis of C-SACs, but also can be extended to prepare other types of SACs.