Porous Cu with a dispersion of nanoscale Al₂O₃ particles is fabricated by freeze-drying CuO-Al₂O₃/camphene slurry and sintering. Camphene slurries with CuO-Al₂O₃ contents of 5 and 10 vol% are unidirectionally frozen at -30°C, and pores are generated in the frozen specimens by camphene sublimation during air drying. The green bodies are sintered for 1 h at 700°C and 800°C in H₂ atmosphere. The sintered samples show large pores of 100 μm in average size aligned parallel to the camphene growth direction. The internal walls of the large pores feature relatively small pores of ~10 μm in size. The size of the large pores decreases with increasing CuO-Al₂O₃ content by the changing degree of powder rearrangement in the slurry. The size of the small pores decreases with increasing sintering temperature. Microstructural analysis reveals that 100-nm Al₂O₃ particles are homogeneously dispersed in the Cu matrix. These results suggest that a porous composite body with aligned large pores could be fabricated by a freeze-drying and H₂ reducing process.

Carbon nanofibers (CNF) are widely used as active agents for electrodes in Li-ion secondary battery cells, supercapacitors, and fuel cells. Nanoscale coatings on CNF electrodes can increase the output and lifespan of battery devices. Atomic layer deposition (ALD) can control the coating thickness at the nanoscale regardless of the shape, suitable for coating CNFs. However, because the CNF surface comprises stable C–C bonds, initiating homogeneous nuclear formation is difficult because of the lack of initial nucleation sites. This study introduces uniform nucleation site formation on CNF surfaces to promote a uniform SnO₂ layer. We pretreat the CNF surface by introducing H₂O or Al₂O₃ (trimethylaluminum + H₂O) before the SnO₂ ALD process to form active sites on the CNF surface. Transmission electron microscopy and energy-dispersive spectroscopy both identify the SnO₂ layer morphology on the CNF. The Al₂O₃-pretreated sample shows a uniform SnO₂ layer, while island-type SnOx layers grow sparsely on the H₂Opretreated or untreated CNF.

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