Single-atom platinum or ruthenium on C4N as 2D high-performance electrocatalysts for oxygen reduction reaction

Pt/C is a practical electrocatalyst for oxygen reduction reaction (ORR) in metal-air batteries and fuel cells, however, also suffers the drawbacks of high cost and instability, which have propelled people to search for new substitutes, such as single-atom metal electrocatalysts. Herein, C 4 N was firstly synthesized from 2,3-diyldiamine phenazine via one-step hydrothermal method rather than the traditional way that two monomers react in organic solvent, and then loaded with single-atom metal (Pt or Ru) to form new electrocatalysts. The so-formed M@C 4 N (M = Pt or Ru) electrocatalysts show more excellent ORR performances with higher half-wave potential and better stability and methanol tolerance as compared with the commercial Pt/C. Specifically, the half-wave potential of 1%Pt@C 4 N and 0.5%Ru@C 4 N is 0.861 V and 0.828 V, respectively. Density functional theory calculations reveal that 1%Pt@C 4 N has stronger adsorption of reactant species and faster kinetics than 0.5%Ru@C 4 N in ORR pathway.