Introducing N atoms into hydrogen-substituted graphdiyne for enhanced NH3 sensing performance at room temperature†

The detection of ammonia at room temperature has important applications in ensuring production safety, indoor air quality and human health. However, existing ammonia sensors tend to be less sensitive at ppb levels. Here, we report a novel material based on hydrogen-substituted graphdiyne (HsGDY), which is formed by annealing at 700 °C in an ammonia atmosphere for 2 h (N-HsGDY-700). The sensor prepared from N-HsGDY-700 has excellent NH₃ sensing capability, high response values, fast responses and good selectivity. The response to 10 ppb of NH₃ at room temperature (20 °C) is −38.5%, showing excellent sensitivity. In addition, the sensor has significantly high selectivity to NH₃ in the presence of typical interfering gases, including CO, CO₂, NO, NO₂, H₂, H₂S, toluene, acetonitrile, formaldehyde, acetone, methanol and ethanol. In addition, the sensor has good long-term stability and fast response with a 49 s response time to 100 ppm of NH₃. The excellent sensing properties of N-HsGDY-700 can be attributed to its highly π-conjugated structure due to its acetylene bonds and doped N atoms, which are favorable for NH₃ adsorption and charge transfer to the N-HsGDY-700 surface.