Novel solid state of silica with ultra-high specific surface area

Catalysis, sorption, separation, energy storage, and biomedicine applications demand well-developed surface area materials. Nanoporous carbon has the largest specific surface area (SSA) among inorganic materials, of about 3000 m² g⁻¹, due to its unique atomic-thin structure. However, the practical efficiency of a material depends on its functional group number, chemical and thermal stability, toxicity, composition purity, and hydrophilicity, and the existing high-SSA materials do not sufficiently satisfy these requirements. Here we report on the synthesis of a new solid state of silica in the form of crumpled sheets of silicon-oxygen tetrahedra with an ultra-high (UH) SSA of 2500 m² g⁻¹. The material prepared by wet chemical synthesis consists of hydrated silica and organic groups mixed at the molecular level, which are associated through the Coulomb and van der Waals forces. After a soft removal of organics, the resulting UH SSA silica has a complex openwork structure with nano-sized pores (0.5–3 nm) separated from each other by the sheet with the thickness close to silicon-oxygen tetrahedron. The obtained micro-mesoporous material has an extremely hydroxylated form, high concentration of surface silanol groups stabilizing the delicate structure and determining its hydrophilicity and tunable surface functionalization, it is also incombustible, non-toxic, biocompatible and environment friendly. These advantageous properties would significantly improve application characteristics, for instance, high adsorption capability, stability in harsh conditions, high sensitivity and selectivity.