Carbothermal shock enabled facile and fast growth of carbon nanotubes in a second

Carbon nanotubes (CNTs) hold great promise in many fields because of their unique structures and properties. However, the preparation of CNTs generally involves cumbersome equipment and time-consuming processes. Here, we report an ultra-fast carbothermal shock (CTS) approach for synthesizing CNTs with a simple homemade setup by employing Joule heating of a carbon substrate. Carbonized silk fabric (CSF) loaded with transition metal salts in ethanol solution was used as the substrate, which was treated with a pulse voltage of 40 V for only 50 ms and then covered with uniform CNTs grown with bimetallic alloy catalyst nanoparticles (diameter: ~ 9 nm). The temperature ramp rate is as high as 10⁵ K/s. The as-obtained sample has a unique fluffy structure similar to the trichobothrium of spiders, endowing it versatile applications such as airflow sensors or air filters. The CTS technique presents an easy-accessible and highly efficient approach for synthesizing CNTs, which may be also applied in synthesizing other nanomaterials.