B and N isolate-doped graphitic carbon nanosheets from nitrogen-containing ion-exchanged resins for enhanced oxygen reduction.

Lei Wang,Honggang Fu,Wei Zhou,Dongdong Zhao,Lu Zhao,Chungui Tian,Ruihong Wang,Jie Yin,Peng Yu

doi:10.1038/srep05184

Abstract

B,N-codoped carbon nanostructures (BNCS) can serve as alternative low-cost metal-free electrocatalysts for oxygen reduction reactions (ORR). However, the compensation effect between the p- (B atoms) and n-type (N atoms) dopants would make the covalent boron-nitride (BN) easily formed during the synthesis of BNCS, leading to a unsatisfactory ORR activity. Therefore, it has been challenging to develop facile and rapid synthetic strategies for highly active BNCS without forming the direct covalent BN. Here, a facile method is developed to prepare B and N isolate-doped graphitic nanosheets (BNGS) by using iron species for saving N element and simultaneous doping the B element from nitrogen-containing ion-exchanged resins (NR). The resulting BNGS exhibits much more onset potential (Eonset) compared with the B-doped graphitic carbon nanosheets (BGS), N-doped graphitic carbon nanosheets (NGS), as well as B,N-codoped disorder carbon (BNC). Moreover, the BNGS shows well methanol tolerance propery and excellent stability (a minimal loss of activity after 5,000 potential cycles) compared to that of commercial Pt/C catalyst. The goog performance for BNGS towards ORR is attributed to the synergistic effect between B and N, and the well electrons transport property of graphitic carbon in BNGS.

Highlights

The two-step method could prevent the combination of B and N, leading to the synthetic B,N-codoped graphene exhibits good performance towards oxygen reduction reactions (ORR), the high-cost of the material derived from graphite oxide (GO) and the complicate synthesized process would limit the realization in practical application
The [Fe(CN)6]32 ions were introduced into the backbone of nitrogen-containing ion-exchanged resins (NR) via a ion-exchanged route to form NR-[Fe(CN)6]32 composite
The N atoms were fixed in the backbone of NR, which could avoid the directly combine between B and N atoms in the B and N isolate-doped graphitic nanosheets (BNGS) during the carbonized process

Summary

Introduction

The two-step method could prevent the combination of B and N, leading to the synthetic B,N-codoped graphene exhibits good performance towards ORR, the high-cost of the material derived from graphite oxide (GO) and the complicate synthesized process would limit the realization in practical application. Despite the tremendous progress in B- and N-codoped CNS for the ORR, to our best knowledge, there have been no reports of the B and N isolate-doped graphitic carbon nanosheets (BNGS) with controllable content of B and N dopants from ion-exchanged route.

Results

Conclusion