Nitrogen-doping hollow carbon nanospheres derived from conjugated microporous polymers toward oxygen reduction reaction

The exploitation non-precious or metal-free electrocatalysts of oxygen reduction reaction (ORR) is of significance for construction of next-generation fuel cells. In this work, hollow-spherical conjugated micro-porous polymers (CMPs) comprising porphyrin units were synthesized as precursors to prepare N-doping porous carbon spheres (CMP-NP-x) by a direct pyrolysis method. The as-resulted CMP-NP-x exhibited spherical morphology with hollow structure similar to that of CMPs precursors. The BET surface area of CMP-NP-x can be tailored by the pyrolysis temperature varying from 868 m(2) g(-1) to 1118 m(2) g(-1). According to XPS analysis, the pyrrolic N content in the sample decreased but the graphitic N and pyridinic N increased with increasing of the pyrolysis temperature from 800 degrees C to 1000 degrees C. Taking advantages of porous structure with large accessible surface areas and N species active sites, the resulting CMP-NP-x showed superior ORR activity and methanol tolerance to commercial Pt/C catalyst. In particular, CMP-NP-900 possesses the highest onset potential (0.930 V), half-wave potential (0.857 V) and limiting current density of 4.45 mA cm(-2), compared with Pt/C catalyst and other samples, making it a promising metal free catalyst superior to commercial Pt/C catalyst in alkalic condition. (C) 2022 Elsevier Inc. All rights reserved.

Automated summary

This work synthesized a new type of non-precious metal catalyst CMP-NP-x, and controlled its surface area and nitrogen content by adjusting the pyrolysis temperature. The experimental results showed that CMP-NP-x exhibited excellent catalytic activity and methanol tolerance in the oxygen reduction reaction, making it more promising than commercial Pt/C catalyst.