Structure-directing synthesis of porous CuO-SiO₂ nanocomposites using carbon nitride

Structure-directing synthesis, such as by the template method, allows us to control the porous structure and morphological properties of solid-state materials. Traditionally, molecules and zero-, one-, and three-dimensional materials have been used as structure-directing agents and templates. Recently, two-dimensional materials (e.g., graphene oxide and graphitic carbon nitride) have been investigated for their use in the synthesis of nanostructured materials. In this study, we used carbon nitride as the structure-directing agent for controlling SiO₂ and cupric oxide (CuO) formation in the development of porous CuO-SiO₂ nanocomposites via the calcination of a mixture of Cu²⁺, polyhedral oligomeric silsesquioxane (POSS), and carbon nitride to solve the problems with CuO (e.g., porosity control and low efficiency per weight relative to light materials). Further, we investigated the formation factors of the nanocomposites using comparative experiments to understand the roles of Cu²⁺, POSS, and carbon nitride. During calcination, carbon nitride induced the formation of SiO₂, which supported CuO; the effect of Cu species removed carbon nitride. Subsequently, porous CuO-SiO₂ nanocomposites were constructed. The constructed CuO-SiO₂ nanocomposites presented a unique morphology (i.e., a fluffy structure), high surface area, and narrow optical band gap. The demonstrated method may pave the way for the design of CuO composite materials and the development of their application as adsorbents and catalysts.