Bio-Inspired Hierarchical Carbon Structures Coated with Zeolite for High-Yield Carbon Nanotube Synthesis

Efficient synthesis of carbon nanotubes (CNTs) remains challenging due to catalyst nanoparticle agglomeration during catalytic chemical vapor deposition (CCVD). In this study, biomorphic carbon materials (BCMs) derived from natural wood were coated with LTA zeolite and used as structured supports for cobalt-catalyzed CNT synthesis. The carbonized BCMs preserved their hierarchical cellular architecture, while the LTA zeolite coating provided a microporous interfacial layer for cobalt catalyst loading. CNTs were synthesized by CCVD using acetylene at 650 °C. CNT growth was successfully achieved on the LTA-zeolite-coated biomorphic supports, with TGA-derived carbon deposition values ranging from 2.21% to 21.82%. Red pine and red cedar exhibited comparatively low carbon deposition values of 2.40% and 2.21%, respectively, whereas cypress and Gorman spruce showed substantially higher values of 21.82% and 21.01%, respectively. The highest carbon deposition value was obtained for the cypress-derived BCM. Transmission electron microscopy confirmed the formation of well-developed multiwalled carbon nanotubes with support-dependent diameters and highly graphitized walls. The results demonstrate successful CNT growth on LTA-zeolite-coated biomorphic carbon supports and reveal pronounced support-dependent differences associated with the biomorphic pore architecture and gas-transport characteristics.