Abstract Cu aerogel is an ideal material as the X‐ray backlight target in laser diagnosis experiments owing to its porous structure and K‐shell X‐ray emission spectrum. However, because of their poor formability and oxidation resistance, the preparation of pure Cu aerogels with nanoscale particles and pores is still difficult. In this study, a Cu aerogel is fabricated by reducing nanoporous Cu‐based aerogels and assembling Cu nanoparticles. Numerous pores ranging from 1 to 10 nm are present in the Cu aerogel, resu…