Mesoporous silicas, especially those exhibiting ordered pore systems and uniform pore diameters, have shown great potential for sensing applications in recent years. Morphological control grants them versatility in the method of deployment whether as bulk powders, monoliths, thin films, or embedded in coatings. High surface areas and pore sizes greater than 2 nm make them effective as adsorbent coatings for humidity sensors. The pore networks also provide the potential for immobilization of enzymes within the materials. Functionalization of materials by silane grafting or through cocondensation of silicate precursors can be used to provide mesoporous materials with a variety of fluorescent probes as well as surface properties that aid in selective detection of specific analytes. This review will illustrate how mesoporous silicas have been applied to sensing changes in relative humidity, changes in pH, metal cations, toxic industrial compounds, volatile organic compounds, small molecules and ions, nitroenergetic compounds, and biologically relevant molecules.

Hybrid macroporous materials with thiol functional groups attached to titania and zirconia frameworks have been prepared via colloidal crystal templating techniques for use as heavy metal ion adsorbents. Synthesis procedures are described for the preparation of thiol–metal oxide materials containing either siloxane or sulfonate linkages. The hybrid macroporous materials were characterized by SEM, FT-IR, ²⁹Si MAS NMR, elemental analysis, and nitrogen adsorption. The materials contained high levels of chemically anchored thiol groups and had uniform porous structures. The hybrid macroporous materials were effective adsorbents for the removal of heavy metal ions from solution, with adsorption capacities ranging from 0.33 to 1.41 mmol g⁻¹ for mercury(II) ions and 0.27 to 1.24 mmol g⁻¹ for lead(II) ions. The hybrid materials remained effective for metal ion adsorption after regeneration by an acid wash, with metal ion loading capacities of the recycled materials being on average two-thirds that of the original capacities. The metal ion adsorption capacity and reusability of hybrid macroporous materials makes them promising adsorbents for wastewater cleanup.