High-Performance MEMS Gas Sensors Utilizing an N-CQD/NiCo2O4 Composite for H2S Detection and Concentration Regression Prediction.

Hydrogen sulfide (H2S) poses significant risks in industrial settings due to its high toxicity and flammability, making its efficient detection crucial for operational safety. In this study, high-performance MEMS gas sensors based on a nitrogen-doped carbon quantum dot/nickel cobaltite (N-CQD/NiCo2O4) nanocomposite were developed, achieving highly sensitive H2S detection. Characterization techniques such as XRD, XPS, SEM, and TEM confirmed the successful loading of N-CQDs onto the NiCo2O4 surface, leading to an increase in oxygen vacancy concentration. The sensor with NCQD/NCO-2 exhibited excellent H2S selectivity, good repeatability, and long-term stability over 40 days. At low-temperature heating, the response to 1000 ppm H2S was enhanced by a factor of 6.84, with a theoretical detection limit of 9.42 ppb. Beyond the material-level enhancement, this work integrates N-CQD-mediated surface/interfacial activation, a low-temperature-heated MEMS sensor array, and a lightweight temporal regression model for H2S quantification. The DCG-Net model achieved accurate concentration prediction with an R2 value of 0.9902 and was successfully deployed, offering a compact material-device-algorithm solution for intelligent H2S monitoring.