Metal-free N, B, F ternary-doped carbon electrocatalyst for boosting the oxygen reduction reaction and high-performance zinc-air battery

Developing efficient metal-free carbon-based electrocatalysts for the oxygen reduction reaction (ORR) is significant and challenging to reduce the cost of fuel cells and metal-air batteries for large-scale applications. Herein, a novel metal-free N, B, F ternary-doped carbon electrocatalyst (FBNC Delta(1:6)-950) exhibited an excellent ORR performance with half-wave potential of 0.858 V vs. reversible hydrogen electrode (RHE) via an almost exclusively four-electron transfer pathway in 0.1 M KOH, even better than the commercial Pt/C (20 %). Moreover, the FBNC Delta(1:6)-950-based zinc-air battery (ZAB) shown an excellent power density of 147 mW.cm(-2) and long-term stability of 100 h. The FBNC Delta(1:6)-950 was constructed via pyrolyzing zeolite imidazole framework (ZIF-8) precursor containing BF4- at 950 degrees C under N-2 to volatilize the Zn. According to the structural characterization and theoretical calculations, B and F from BF4- not only increased the number of active sites of pyridine-N by etching intact carbon matrix, but also co-modified part of pyridine-N to further optimize the electronic structure and reduce the adsorption energy of *OH, both of which together result in the excellent performance of FBNC Delta(1:6)-950. This work provides a fresh perspective on the advancement of highly active metal-free carbon-based electrocatalysts for the ORR and ZAB.