B, N Codoped and Defect‐Rich Nanocarbon Material as a Metal‐Free Bifunctional Electrocatalyst for Oxygen Reduction and Evolution Reactions

Abstract

The development of highly active, inexpensive, and stable bifunctional oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) catalysts to replace noble metal Pt and RuO2 catalysts remains a considerable challenge for highly demanded reversible fuel cells and metal–air batteries. Here, a simple approach for the facile construction of a defective nanocarbon material is reported with B and N dopants (B,N‐carbon) as a superior bifunctional metal‐free catalyst for both ORR and OER. The catalyst is prepared by pyrolyzing the composites of ethyl cellulose and high‐boiling point 4‐(1‐naphthyl)benzeneboronic acid in NH3 atmosphere with an inexpensive Zn‐based template. The obtained porous B,N‐carbon with rich carbon defects exhibits excellent ORR and OER performances, including high activity and stability. In alkaline medium, B,N‐carbon material shows high ORR activity with an onset potential (E onset) reaching 0.98 V versus reversible hydrogen electrode (RHE), very close to that of Pt/C, a high electron transfer number and excellent stability. This catalyst also presents the admirable ORR activity in acidic medium with a high E onset of 0.81 V versus RHE and a four‐electron process. The OER activity of B,N‐carbon is superior to that of the precious metal RuO2 and Pt/C catalysts. A Zn–air battery using B,N‐carbon as the air cathode exhibits a low voltage gap between charge and discharge and long‐term stability. The excellent electrocatalytic performance of this porous nanocarbon material is attributed to the combined positive effects of the abundant carbon defects and the heteroatom codopants.

B, N Co‐Doped Three‐Dimensional Carbon Aerogels with Excellent Electrochemical Performance for the Oxygen Reduction Reaction

“…It is found that the contents of pyridinic N and graphitic N are clearly higher than that of pyrrolic N, suggesting the excellent electrocatalytic activity of BN‐CA‐900 for ORR may be expected according to the previous reports . The B 1s high‐resolution spectra of the BN‐CA‐900 (Figure d) show four peaks at 190.2, 191.1, 192.3, and 190.7 eV, which could be ascribed to the BC 3 , BC 2 O, BCO 2 , and B−N configurations, respectively, indicating the multi‐model existence of B in BN‐CA‐900. The XPS analysis proves that we have successfully synthesized B, N co‐doped carbon materials.…”

In Situ Synthesis and Electrocatalytic Performance of Fe/Fe2.5C/Fe3N/Nitrogen‐Doped Carbon Nanotubes for the Oxygen Reduction Reaction

“…In addition, carbon defects are also created by the release of some gases from the decomposition of the precursor during the graphitization process. Numerous studies have shown that carbon defects are favorable to provide more active sites and the transfer of electrons, which are beneficial to accelerate the ORR process.…”

“…There are two kinds of lattices of 0.190 nm and 0.208 nm in the HRTEM images of Fe x C y N z /N‐CNT‐30, which corresponds to the (110) plane of Fe and the (021) plane of Fe 2.5 C or the (111) plane of Fe 3 N, respectively . In addition, Figure f reveals the well‐graphitized carbon layers with some broken fringes in the shells and a twisted morphology . By combining with HRTEM and the Raman spectra results, it is can be reasonably deduced that Fe x C y N z /N‐CNT‐30 possesses abundant carbon defects, which is believed to play a positive effect on ORR activity.…”

Recent Advances in Carbon‐Based Bifunctional Oxygen Catalysts for Zinc‐Air Batteries

“…In general, heteroatom doping often induces crystalline disorder and representative defects, such as vacancies, lattice reconstruction, and dangling groups, which could also significantly enhance the catalytic activities . Extensive research efforts have been devoted to investigating the nanostructured carbon with both heteroatom doping and abundant structural defects for oxygen catalysis in ZABs . Studt et al.…”