Improved oxygen reduction performance of a N, S co-doped graphene-like carbon prepared by a simple carbon bath method

Rationally designing and optimizing metal-free electrocatalysts for the oxygen reduction reaction (ORR) is of great importance for fuel cells and metal-air batteries, but remains a great challenge. A N,S-codoped graphene-like carbon (GLC) was synthesized by a simple carbon-bath pyrolysis method, in which urea and thiourea (1:1 w/w) were used as both the sacrificial template and source of nitrogen and sulfur, and glucose as the carbon precursor. A mixture of these materials was placed in a crucible that was contained in a larger crucible full of carbon powder. Compared with N-doped or S-doped GLCs synthesized using only urea or thiourea, respectively, the N,S-codoped GLC had a pore volume of 0.63 cm(3)/g and a larger specific surface area of 583.68 m(2)/g, the highest micropore to total surface area of 29.39% and micropore to total pore volume of 12.70%, and the highest pyridinic-N and graphitic-N content of up to 92.2%. The N,S-codoped GLC showed a high electrocatalytic activity for ORR with a mid-wave potential (E-1/2) of 0.82 V-RHE, which was more positive than that of Pt/C (E-1/2=0.80 V-RHE) in an alkaline electrolyte. The N, S-codoped GLC catalyst had better stability and superior methanol tolerance compared with commercial Pt/C (20 wt%), a benchmark catalyst.