Fe-Doped CuGaO₂ Nanoparticles-Based Gas Sensor for Sub-ppm Triethylamine Detection

Metal–oxide–semiconductor, an important type of electronic material with the chemiresistive effect, plays the crucial role in the gas sensing application, especially the trace detection of compounds related to the human health issue. Herein, a new gas sensor is proposed on the basis of the Fe-doped p-type delafossite CuGaO2 nanoparticles, which provides an improved selectivity to common organic gases and response (4–10-ppm triethylamine) at low operation temperature of 160 °C with short response/recovery time (15/120 s) and long-term stability (fluctuation ~5%) in trace detection down to sub-ppm level (38 ppb). Based on the microstructural characterization and gas detection test results, the first-principles calculations based on density function theory (DFT) have been performed to reveal the gas sensing mechanism. The calculated adsorption energy and Bader charge has a counterpart in the response order to the target gases, which confirms that the chemiresistive signal is generated by the direct adsorption followed by the charge transfer. Furthermore, the charge distribution analysis confirms that Fe dopant has a synergistic effect with Cu adatom in both adsorption and electron transfer procedures, in addition to the elevation of intrinsic conductivity of the CuGaO2 substrate. It is a new aspect to investigate the functional metal–oxide–semiconductor-based chemiresistive gas sensors, which provides an approach to develop the hybrid material system toward the target gas component.