Compact disc-based sensor utilizing Er₂O₃/Co₃O₄ nanorods anchored on rGO nanosheets for enhanced detection of...

A cost-effective rGO-Er₂O₃/Co₃O₄ (rGO-ECO) nanocomposites based hydrogen sulfide (H₂S) gas sensor was developed by utilizing a Compact Disc Electrode (CDE). XRD of rGO-ECO-6 composite showed a cubic crystalline structure with a crystallite size of ∼7.23 nm and HR-TEM shows a nanorod-like morphology. XPS analysis identified Er³⁺ (167.8, 172.4 eV) and Co³⁺ (779.6, 794.4 eV) states with oxygen vacancies and strong interfacial interactions, enhancing surface reactivity of the rGO-ECO-6 composite. EPR analysis revealed a defect-related signal at g ≈ 2.003, indicating abundant oxygen vacancies, while BET measurements showed a specific surface area of 59.18 m² g^-1, supporting enhanced gas adsorption in the rGO-ECO-6 composite. Among the rGO-ECO composites with varying erbium content, rGO-ECO-6 exhibited the most favourable structural and surface properties, making it suitable candidate for gas sensor applications. The rGO-ECO-6 composite formed a p-n heterojunction, significantly improving charge transport and gas adsorption capabilities due to the synergistic interaction between Co₃O₄, Er₂O_3, and rGO. The fabricated sensor exhibited outstanding performance for 10 ppm H₂S at room temperature, achieving a high sensor response (75%), rapid response (47 s) and recovery (11 s) times, excellent sensitivity (0.1441 ppm^-1), and low detection limit (1.11 ppm). Furthermore, the sensor demonstrated excellent selectivity, long-term stability over 100 days, and strong reproducibility with low RSD. Humidity tolerance was also evaluated, confirming reliable sensor operation across the 12-90% RH range. The results exhibit the potential of the rGO-ECO-6 nanocomposite as a promising candidate for real-time, low-power H₂S sensing in industrial safety and environmental monitoring applications.