Atomically Dispersed FeN2 at Silica Interfaces Coupled with Rich Nitrogen Doping-Hollow Carbon Nanospheres as Excellent Oxygen Reduction Reaction Catalysts
Atomically Dispersed FeN2 at Silica Interfaces Coupled with Rich Nitrogen Doping-Hollow Carbon Nanospheres as Excellent Oxygen Reduction Reaction Catalysts
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DOI：
10.1021/acsaem.2c01507
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发表时间：
2022-09
影响因子：
6.4
通讯作者：
Tianwen Wu;Qingmin Hu;Hongbin Zhao;Xiaowei Cheng;Haibo He;Junping Dong;Jiaqiang Xu
中科院分区：
文献类型：
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作者：
Tianwen Wu;Qingmin Hu;Hongbin Zhao;Xiaowei Cheng;Haibo He;Junping Dong;Jiaqiang Xu
sio2辅助策略是制备高性能氧还原反应（ORR）催化剂的一种很有前途的方法。本研究采用二氧化硅界面辅助制备了原子分散的富氮掺杂纳米碳球催化剂。具有超薄sio2层（~ 3nm）的Fe-N /C@SiO2catalysts来源于ZIF-8@Fe/ sio2复合材料。将多孔sio2薄层包裹在ZIF-8表面，并通过一步合成将Fe原子装入二氧化硅中。与传统的合成策略不同，不需要额外的后处理，如sio2涂层的蚀刻和二次热解。ORR活性和稳定性高度依赖于sio2层的厚度。刚性sio2层不仅捕获了表面的挥发性氮，实现了高氮掺杂（11.14%），而且防止了ZIF框架的坍塌，形成了分层多孔结构。更重要的是，单个Fe原子以fen2构型的形式锚定在催化剂的外表面，从而大大提高了ORR活性。由于无活性二氧化硅层的辅助，在碱性介质中实现了显著的稳定性（操作14小时后活性衰减仅为1%）。
A SiO2-assisted strategy is a promising approach to prepare high-performance oxygen reduction reaction (ORR) catalysts. In this work, atomically dispersed FeN2on rich nitrogen doping-hollow carbon nanosphere catalysts were prepared by silica interface assists. The Fe–N/C@SiO2catalysts with an ultrathin SiO2layer (∼3 nm) were derived from ZIF-8@Fe/SiO2composites. A porous SiO2thin layer was wrapped on a ZIF-8 surface while loading Fe atoms inside silica by one-step synthesis. Different from the conventional synthetic strategy, no additional post-treatments such as etching of SiO2coatings and second pyrolysis are required. The ORR activity and stability are highly dependent on the thickness of the SiO2layer. The rigid SiO2layer not only traps the volatile nitrogen species on the surface to achieve a high nitrogen doping (11.14%) but also prevents the ZIF framework from collapse, forming hierarchical porous structures. Also more importantly, single Fe atoms are anchored in situ on the outer surface of the catalysts in the form of FeN2configuration, thus greatly boosting the ORR activities. Remarkable stability (only 1% activity attenuation after 14 h of operation) is achieved in alkaline media due to the assist of inactive silica layers.