<p>Silica nanosheets (SiO₂-NS) have drawn extensive interest in recent years due to their unique characteristics, including high specific surface area, narrow pore size distribution, high mechanical strength, controllable surface chemistry, and biocompatibility. Such characteristics make them excellent candidates for various applications, particularly in adsorption and sensing. However, the wet chemical synthesis of free-standing silica nanosheets with controllable thickness and textural properties remains a significant challenge. Here, we report synthetic method to synthesize flat, layered mesoporous silica nanosheets (SiO₂-NS) by chemical reduction of silicon tetrabromide (SiBr₄) using cetyltrimethylammonium bromide (CTAB) as a soft lamellar micelle template in a water–ethanol mixed solvent system. The resulting silica nanosheets exhibit lateral dimensions of 100–200&#xa0;nm and ultrathin thicknesses of approximately 1&#xa0;nm. The synthesized SiO₂-NS&#xa0;possesses outstanding textural properties, including a BET surface area of 971&#xa0;m²g⁻¹, a mean&#xa0;BJH pore diameter of 2.56&#xa0;nm, and&#xa0;a total pore volume of 0.73&#xa0;cm³g⁻¹. These structural properties enable the nanosheets to function as high-performance amine sorbents and, most significantly, highly sensitive room-temperature trimethylamine (TMA) sensors. The sensors exhibit a brief recovery time and rapid response, which demonstrates the material’s promise in medical diagnostics, environmental monitoring, and food quality applications.</p> Graphical abstract <p>Inorganic synthesis of silica with different morphologies as a function of CTAB concentration, and the evolution of silica nanosheets</p>