N-doped graphdiyne derivative for highly selective and ultrasensitive NH₃ sensing at room temperature

The detection of ammonia (NH₃) at room temperature is of paramount importance for human health, production safety, and environmental protection. However, the application of common NH₃-sensitive materials is seriously limited by their low sensitivity and poor selectivity. Herein, starting from molecular structure design, an N-doped graphdiyne derivative (N-GDYD) with a definite N-doping site was synthesized via the Glaser coupling of 2,4,6-tris((trimethylsilyl) ethynyl)-1,3,5-triazine. Owing to the rich ethynyl groups and triazine N atoms, the N-GDYD gas sensor showed excellent NH₃ sensing performance at room temperature (20 °C). For instance, it possessed a high response value of -67.7%, an extremely short response time of 92 s, and a short recovery time of 280 s for 100 ppm NH₃. Although the NH₃ concentration decreased to 10 ppb, it still exhibited a response of -12.4%. In particular, the N-GDYD gas sensor exhibited a specific response to NH₃ and showed negligible responses to 13 other types of gases and organic reagent vapors. In situ UV-vis spectra and DFT calculation results confirmed that the alkyne bond and N atoms in the triazine ring were the adsorption sites for NH₃. These active sites have strong interactions with NH₃ and thus promoted electron transportation from the NH₃ molecules to N-GDYD. Evidently, this work provides a new strategy for the design of high-performance NH₃ sensing materials.