Issue 5, 2017

Active sites engineering leads to exceptional ORR and OER bifunctionality in P,N Co-doped graphene frameworks

Abstract

Bifunctional catalysts for the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) are highly desirable for rechargeable metal–air batteries and regenerative fuel cells. However, the commercial oxygen electrocatalysts (mainly noble metal based) can only exhibit either ORR or OER activity and also suffer from inherent cost and stability issues. It remains challenging to achieve efficient ORR and OER bifunctionality on a single catalyst. Metal-free structures offer relatively large scope for this bifunctionality to be engineered within one catalyst, together with improved cost-effectiveness and durability. Herein, by closely coupled computational design and experimental development, highly effective bifunctionality was achieved in a phosphorus and nitrogen co-doped graphene framework (PNGF) – with both ORR and OER activities reaching the theoretical limits of metal-free catalysts, superior to their noble metal counterparts in both (bi)functionality and durability. In particular, with the identification of active P–N sites for OER and N-doped sites for ORR, we successfully intensified these sites by one-pot synthesis to tailor the PNGF. The resulting catalyst achieved an ORR potential of 0.845 V vs. RHE at 3 mA cm−2 and an OER potential of 1.55 V vs. RHE at 10 mA cm−2. Its combined ORR and OER overpotential of 705 mV is much lower than those previously reported for metal-free bifunctional catalysts.

Graphical abstract: Active sites engineering leads to exceptional ORR and OER bifunctionality in P,N Co-doped graphene frameworks

Supplementary files

Article information

Article type
Paper
Submitted
25 Nov 2016
Accepted
13 Mar 2017
First published
13 Mar 2017
This article is Open Access
Creative Commons BY license

Energy Environ. Sci., 2017,10, 1186-1195

Active sites engineering leads to exceptional ORR and OER bifunctionality in P,N Co-doped graphene frameworks

G. Chai, K. Qiu, M. Qiao, M. Titirici, C. Shang and Z. Guo, Energy Environ. Sci., 2017, 10, 1186 DOI: 10.1039/C6EE03446B

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