Carbon Dots-Modified Hollow Mesoporous Photonic Crystal Materials for Sensitivity- and Selectivity-Enhanced Sensing of Chloroform Vapor

• Uniform-sized hollow mesoporous silica spheres form colloidal photonic crystals for gas sensing. • 'Nanoreceptors' have been introduced for increasing the sensing sensitivity and specificity. • A chloroform gas sensor is created with a sensitivity of 0.79 nm ppm−1 with a limit of detection of 3.22 ppm, which are the best reported values in fast-response chloroform vapor sensors without multi-signal assistance. • The sensor exhibits fast response (7.5 s positive, 9 s negative) and stable performance across a wide range of humidity (20–85% RH) and temperature (25–55 °C).