Recent advances in synthesis of reshaped Fe and Ni particles at the tips of carbon nanofibers and their catalytic applications

• Catalytic chemical vapor deposition is an efficient and economic method to prepare the reshaped metal catalysts.
• Carbon adsorbates induced effect is one of the key factors governing the reshaping of metal particles.
• The reshaped catalysts are highly efficient for cellulose conversion, selective hydrogenation and ammonia decomposition.
• Metal particles over the reshaped catalysts are highly dispersed and spatially isolated, exhibiting higher stability.

Transition metals such as Fe and Ni are the most commonly used catalysts for the growth of carbon nanofibers (CNFs) via CCVD method, and they always remain in the raw products. Much attention has been paid to purify CNFs, i.e., to remove residual metal particles and supports, before their use in most cases. However, some recent studies show that the residual metal particles usually attach at the tips of CNFs, and exhibit a different shape in comparison with the initial metal catalysts and as a result unique catalytic performance. The present review focuses on the state-of-the-art of the developments of synthesis of reshaped Fe and Ni particles at the tips of CNFs and their catalytic applications in cellulose conversion, selective hydrogenation and ammonia decomposition. In particular, effects of catalyst support, carbon source and its concentration, reaction temperature and etching gas are discussed. Moreover, the carbon adsorbates induced effect is highlighted as one of the key factors governing the reshaping of Fe and Ni particles.

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