Molten Salt‐Assisted Synthesis of Porous Precious Metal‐Based Single‐Atom Catalysts for Oxygen Reduction Reaction

Abstract

Abstract Precious metal‐based single‐atom catalysts (PM‐SACs) hosted in N‐doped carbon supports have shown new opportunities to revolutionize cathodic oxygen reduction reaction (ORR). However, stabilizing the high density of PM‐N x sites remains a challenge, primarily due to the inherently high free energy of isolated metal atoms, predisposing them to facile atomic agglomeration. Herein, a molten salt‐assisted synthesis strategy is proposed to prepare porous PM 1 /N‐C Pores (PM = Ru, Pt, and Pd) electrocatalysts with densely accessible PM‐N x sites. A hierarchically porous N‐doped carbon substrate (N‐C Pores ), synthesized via the NaCl‐assisted pyrolysis of zeolitic imidazolate framework‐8, effectively improves the utilization of PM‐N x sites by increased reactants accessible surface area and reduced mass transfer resistance. In accordance with theoretical calculations, the as‐prepared Ru 1 /N‐C Pores , featuring superior intrinsic active Ru‐N 4 sites, exhibit outstanding ORR turnover frequency of 6.19 e − site −1 s −1 , and outperforms the commercial Pt/C with a 5.3‐fold of mass activity (5.83 ± 0.61 A mg −1 ) at 0.8 V versus reversible hydrogen electrode. The commendable activity and stability of Ru 1 /N‐C Pores in a real fuel cell device further affirm its practical applicability.