Enhanced Fe dispersion via “pinning” effect of thiocyanate ion on ferric ion in Fe-N-S-doped catalyst as an excellent oxygen reduction reaction electrode

 Chengyong Shu, Yuanzhen Chen^∗, Xiao-Dong Yang, Yan Liu, Shaokun Chong, Yuan Fang, Yongning Liu, Wei-Hua Yang

highlight

• Improved iron salts stability and dispersibility by the introduction of SCN-.
• High oxygen reduction reaction activity in both acidic and alkalinen medium.
• Operation for 400 h as a cathode electrode in direct methanol fuel cell.
• Have an explicit cyanide N and pyrrolic N functional groups.  

In this study, by using thiocyanate as an iron ion dispersing agent, the pinning effect of thiocyanate ion (SCN-) enables the high dispersion of Fe3+ in a nitrogen-doped carbon polymer and significantly promotes ORR catalysis in both acidic and alkaline media. It shows 47.3 A g-1 kinetic ORR current density in 0.1 M H2SO4 solution at 0.8 V vs. RHE. In addition, SCN- can dope into the base material and modify the surface of catalysts,which generates strong cyanide N functional groups. Additionally, it also has a higher BET surface area and more uniform granularity, which accounts for the enhancement in mass transport.