Strategic Structure Tuning of Yolk‐Shell Microcages for Efficient Nitrogen Fixation

• Published in: ChemSusChem 2021-06, Vol.14 (12), p.2521-2528
• Main Authors: Guo, Huinan, Li, Weiqin, Chen, Kai, Yue, Mengyuan, Huang, Yike, Liu, Yafei, Shao, Huaxu, Chen, Chengcheng, Wang, Caiyun, Wang, Yijing
• Format: Article
• Language: English
• Subjects: Ammonia; Bamboo; Carbon nanotubes; Catalysts; Chemical reduction; cobalt; Diffusion effects; electrocatalysis; N-doping; Nanocrystals; Nitrogen; nitrogen fixation; Nitrogenation; Pyrolysis; Structural engineering; yolk–shell
• ISSN: 1864-5631; 1864-564X
• DOI: 10.1002/cssc.202100502

The electrocatalytic nitrogen reduction reaction (ENRR) under ambient conditions is considered as a promising process to produce ammonia. Towards highly efficient catalysts, here an optimized one‐step pyrolysis strategy was tailored to design yolk–shell microcages (YS Co@C/BLCNTs), consisting of Co nanocrystals encapsulated in N‐doped carbon framework and bridged by bamboo‐like carbon nanotubes (BLCNTs). The cavity created between yolk and shell not only served as a “micro‐bag” to store the reactant N2 and enhance its dissolution, but also induced a “cage effect” to confine the diffusion of reaction intermediate, hence making the reaction proceed in the direction of producing NH3. This catalyst displayed excellent catalytic activities for ENRR: a high NH3 yield of 12.87 μg mgcat−1 h−1 at a high faradaic efficiency of 20.7 % at −0.45 V (vs. reversible hydrogen electrode, RHE). After 5 cycles of consecutive ENRR process, the NH3 yield rate was 11.29 μg mgcat−1 h−1, indicating the excellent electrocatalytic stability. These results provide a structural engineering for ENRR catalyst with doped N, cooperating with non‐precious metal to activate the inert triple bond of N2 and achieve NH3 fixation. In the bag: An optimized one‐step pyrolysis strategy is used to design yolk–shell microcages (YS Co@C/BLCNTs), consisting of Co nanocrystals encapsulated in N‐doped carbon framework and bridged by bamboo‐like carbon nanotubes (BLCNTs).The yolk–shell microcage catalyst integrates the advantages of “micro‐bag” and “cage effect” to realize effective nitrogen fixation.