Self-generated carbon nanotubes for protecting active sites on bifunctional Co/CoOx schottky junctions to promote oxygen reduction/evolution reactions via efficient valence transition
Self-generated carbon nanotubes for protecting active sites on bifunctional Co/CoOx schottky junctions to promote oxygen reduction/evolution reactions via efficient valence transition
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自生成碳纳米管，用于保护双功能 Co/CoOx 肖特基结上的活性位点，通过有效的价态跃迁促进氧还原/放出反应
DOI：
10.1016/j.jcis.2019.09.060
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发表时间：
2019
影响因子：
9.9
通讯作者：
Zou Jinlong
中科院分区：
文献类型：
--
作者：
Zhang Peng;Cai Zhuang;You Shijie;Wang Fangyu;Dai Ying;Zhang Chunyue;Zhang Yanhong;Ren Nanqi;Zou Jinlong
防止活性物种的聚集和腐蚀是获得稳定的氧还原反应（ORR）和析氧反应（OER）催化活性的可行途径。本文中，通过使用Co螯合的三聚氰胺前体，自生成竹节状N掺杂碳纳米管（中空BS-NCNT作为壳）以原位包裹Co/CoOx Schools结（核），从而获得作为双功能ORR/OER催化剂的Co/CoOx@ BS-NCNT。对于ORR，Co/CoOx@ BS-NCNT（700 °C）表现出比商业Pt/C（10重量%）更正的峰（0.822 V vs. RHE）和半波（0.842 V vs. RHE）电势。BS-NCNTs的上级ORR活性主要归因于在具有高电导率和活性N物种的管状结构中包裹的CoOx中富集的配位不饱和Co2+（四面体CoTd 2+）。此外，碳纳米管的π-π键被N取代激活，这提供了惊人的电子捕获和传输能力，用于增强ORR活性。对于OER，Co/CoOx@ BS-NCNT（700 °C）获得的电势（1.590 V vs. RHE）小于RuO 2/C在10 mA cm−2时的电势。Co/CoOx@BS-NCNTs（700 °C）的出色OER活性和耐久性源于C-骨架和Co物种之间的强相互作用，以及由外部生长的CNT保护的有效Co 3 +/Co 4+（Co 4 +OOH作为活性位点）转变。此外，CoOx表面丰富的氧空位可以促进OH−/或OER相关中间体的吸附，从而提高OER活性。因此，这项研究为开发具有高催化活性和稳定性的能量转换的NCNTs包裹的Co物种提供了一种有前途的策略。
Protecting active species from aggregation and corrosion may be feasible to obtain stable catalytic activities for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Herein, bamboo-shapedN-doped carbon nanotubes (hollow BS-NCNTs as shells) are self-generated to in situ wrap the Co/CoOxschottky junctions (cores) to obtain the Co/CoOx@BS-NCNTs as bifunctional ORR/OER catalysts by using the Co-chelated melamine precursor. For ORR, Co/CoOx@BS-NCNTs (700 °C) exhibits more positive peak (0.822 V vs. RHE) and half-wave (0.842 V vs. RHE) potential than those of commercial Pt/C (10 wt%). Superior ORR activity is mainly attributed to the enriched coordination-unsaturated Co2+(tetrahedral CoTd2+) in the CoOxwrapped in the tubular structure of BS-NCNTs featuring high electrical conductivity and active N species. Moreover, the π-π bonds of CNTs are activated by N substitution, which provides a stunning electron capture and transmission capability for enhancing ORR activity. For OER, Co/CoOx@BS-NCNTs (700 °C) obtains a smaller potential (1.590 V vs. RHE) than that of RuO2/C at 10 mA cm−2. The outstanding OER activity and durability of Co/CoOx@BS-NCNTs (700 °C) originates from strong interactions between C-skeleton and Co species, and efficient Co3+/Co4+(Co4+OOH as active sites) transition protected by the externally-grown CNTs. Furthermore, abundant oxygen vacancies on CoOxsurface can facilitate the adsorption of OH−/or OER-related intermediates to improve OER activity. Therefore, this study provides a promising strategy to develop NCNTs-wrapped Co species with high catalytic activity and stability for energy conversion.