Direct preparation and conversion of copper hydroxide-based monolithic xerogels with hierarchical pores

Abstract

Copper hydroxide-based monolithic xerogels with controlled hierarchical pores have been prepared directly by a sol–gel process from an ionic precursor, CuCl₂·2H₂O. Propylene oxide acts as a gelation inducer by increasing pH homogeneously in a reaction solution. Poly(acrylamide) is utilized not only to control macroscopic phase separation but also to support the network physically. Glycerol contributes to the formation of monolithic gels by suppressing the growth of copper hydroxide crystals. An appropriate starting composition leads to co-continuous gel skeletons and macropores. Although the as-dried gels were amorphous, post-treatments (calcination and solvothermal treatment) formed metallic copper and copper oxides (CuO and Cu₂O) without the collapse of the monolithic form and macrostructure.