Visible-light-driven room-temperature gas sensor based on carbyne nanocrystals

Abstract Most gas sensors are fabricated from semiconducting metal oxides or two-dimensional nanomaterials. This study demonstrates a visible-light-driven room-temperature gas sensor made of novel carbyne nanocrystals. Carbyne nanocrystals were synthesized by laser ablation in liquids. X-ray diffraction showed that the nanocrystals were monocrystalline. Scanning electron microscopy and transmission electron microscopy revealed that they were stacked flakes consisting of rod-like crystals approximately 10 nm wide and 50–100 nm long. Under illumination by 447 nm light, a sensor containing the nanocrystals detected NO2 molecules at concentrations as low as 2 ppm at room temperature, with response and recovery times of less than 100 s. The light-driven sensing was attributed to the fluorescence emission of the carbyne nanocrystals. The device also exhibited good selectivity and stability. First-principles calculations showed that the carbyne nanocrystals had a high adsorption energy for NO2 molecules and low adsorption energies for other gases, resulting in sensitive NO2 detection. These findings demonstrate the potential of carbyne nanocrystals for use as a gas sensing material.