Effect of Porous and Highly N,O-Doped Amorphous Carbon Materials with Defects Generated by KOH Etching on the Stability of ORR Catalysts

Abstract

A porous N-doped carbon (PNC) carrier with high N content, a rich pore structure, and a high specific surface area was prepared by high-temperature carbonization of polyaniline (CPANI) and KOH activation. The influence of KOH activation on the structure of the carriers was discussed through structural and morphological characterization. The PNC-2 (the mass ratio of CPANI/KOH was 1:2) carrier had more pyridine N- and O-containing functional groups that were conducive to the oxygen reduction reaction (ORR) activity and stability of catalysts. Then, PtCo alloy was loaded into carriers by the immersion method, obtaining a series of catalysts for the ORR. In acidic media, PtCo/PNC-2 has the best performance (Tafel slope = 65.7 mV dec^–1, electron-rich active surface area (ECSA) = 129.2 m²g_Pt^–1, half-wave potential = 0.913 V), whose initial current density was 97 mA cm^–2 and maximum power density was 676 mW cm^–2 in a single-cell test. After 10,000 potential cycles, the mass activity of the PtCo/PNC-2 catalyst retained at 85%. Finally, it was confirmed that high pyridine N- and O-containing functional group contents could effectively inhibit the agglomeration and shedding of PtCo nanoparticles in the durability test. It can be seen that PNC carriers are beneficial for improving the performance of ORR catalysts.