Diamondoid Nanostructures as sp³ -Carbon-Based Gas Sensors

Diamondoids, sp³ -hybridized nanometer-sized diamond-like hydrocarbons (nanodiamonds), difunctionalized with hydroxy and primary phosphine oxide groups, enable the assembly of the first sp³ -C-based chemical sensors by vapor deposition. Both pristine nanodiamonds and palladium nanolayered composites can be used to detect toxic NO₂ and NH₃ gases. This carbon-based gas sensor technology allows reversible NO₂ detection down to 50 ppb and NH₃ detection at 25-100 ppm concentration with fast response and recovery processes at 100 °C. Reversible gas adsorption and detection is compatible with 50 % humidity conditions. Semiconducting p-type sensing properties are achieved from devices based on primary phosphine-diamantanol, in which high specific area (ca. 140 m²  g^-1 ) and channel nanoporosity derive from H-bonding.