Active sites engineering leads to exceptional ORR and OER bifunctionality in P,N Co-doped graphene frameworks
Active sites engineering leads to exceptional ORR and OER bifunctionality in P,N Co-doped graphene frameworks
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DOI：
10.1039/c6ee03446b
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发表时间：
2017-05-01
影响因子：
32.5
通讯作者：
Guo, Zhengxiao
中科院分区：
文献类型：
--
作者：
Chai, Guo-Liang;Qiu, Kaipei;Guo, Zhengxiao
氧还原反应（ORR）和析氧反应（OER）的双功能催化剂是可充电金属-空气电池和再生燃料电池非常需要的催化剂。然而，商用氧电催化剂（主要是贵金属基）只能表现出ORR或OER活性，并且还存在固有的成本和稳定性问题。在单一催化剂上实现高效的ORR和OER双功能仍然具有挑战性。无金属结构为在一种催化剂内设计这种双功能提供了相对较大的范围，同时提高了成本效益和耐用性。在此，通过紧密耦合的计算设计和实验开发，在磷和氮共掺杂的石墨烯框架（PNGF）中实现了高效的双功能- ORR和OER活性均达到无金属催化剂的理论极限，在（bi）功能和耐用性方面优于贵金属催化剂。特别是，通过鉴定OER的活性P-N位点和ORR的n掺杂位点，我们成功地通过一锅合成强化了这些位点，以定制PNGF。所得催化剂在3 mA cm（-2）下的ORR电位为0.845 V，在10 mA cm（-2）下的OER电位为1.55 V。其ORR和OER的总过电位为705 mV，远低于此前报道的无金属双功能催化剂。
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.