Exploring stable non-precious catalysts with excellent activities for electrochemical oxygen reduction is vital for minimizing noble metal consumption in the study of sustainable energy technologies.  

Single-atom Fe homogenously anchored on N-doped carbon (Fe-N_x/C) catalysts are considered as the most promising candidate. However, environmentally hazardous and toxic solvents as well as acid are necessarily needed in the synthesis of Fe-N_x/C catalysts, restricting the application on a large scale.  

"Considering the overall factors of practical application, we must propose a green synthesis method for highly efficient catalysts," said Prof. LIANG Hanpu from the Qingdao Institute of Bioenergy and Bioprocess Technology (QIBEBT) of the Chinese Academy of Sciences (CAS).  

Recently, a research team led by Prof. LIANG reported the facile and environment-friendly synthesis of a single-atom Fe catalyst. Their study was published in ACS Sustainable Chemistry & Engineering. 

The researchers synthesized iron doped ZIF8 precursor in aqueous solution, which was followed by one-step high temperature pyrolysis without the need for subsequent acid leaching. Then, they obtained rod-like nitrogen doped carbon nanorods decorated with isolated Fe-N₄ sites (Fe-SA/NCS).  

The as-synthesized Fe-SA/NCS catalyst exhibited remarkable electrocatalytic performance and long-term stability for oxygen reduction reaction both in KOH and HClO₄, which was attributed to Fe-N₄ active sites.  

Moreover, the Zinc-Air battery with Fe-SA/NCS as cathode material exhibited a relatively low charge/discharge overpotential, higher power density as well as long-term rechargeable stability compared to commercial JM Pt/C catalyst.  

The synthetic strategy developed in this study affords an efficient approach for the green synthesis of non-precious single-atom catalysts for high-performance fuel cells and metal-air batteries.