School of Chemical Engineering and Technology Xi''an Jiaotong University Xi''an 710049 China;
School of Chemical Engineering and Technology Xi''an Jiaotong University Xi''an 710049 China;
CSIRO Mineral Resources Clayton Vic 3168 Australia;
School of Materials Science and Engineering Central South University Changsha 410083 China;
State Key Laboratory of Space Power-Sources Technology Shanghai Institute of Space Power-Sources Shanghai 200245 China;
School of Chemical Engineering and Technology Xi''an Jiaotong University Xi''an 710049 China;
State Key Laboratory of Materials-Oriented Chemical Engineering School of Energy Science and Engineering and Institute of Advanced Materials Nanjing Tech University Nanjing 211800 China;
fuel cells; metal-free catalysts; nitrogen-doped porous carbon; oxygen reduction reaction;