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<p>This study explores the synthesis and gas sensing properties of cobalt oxide (Co<sub>3</sub>O<sub>4</sub>), reduced graphene oxide (rGO), and rGO/Co<sub>3</sub>O<sub>4</sub> composite thin films, fabricated using pulsed laser ablation (PLA) and drop-casting techniques. The synthesis was performed using a Q-switched Nd:YAG laser (1064&#xa0;nm, 10&#xa0;ns pulse width, 4&#xa0;Hz repetition rate, 140&#xa0;mJ energy) with laser pulses ranging from 300 to 1000 pulses to control nanoparticle size. FE-SEM analysis revealed a particle size range of 23.9–51&#xa0;nm, while XRD confirmed a polycrystalline cubic spinel structure for Co<sub>3</sub>O<sub>4</sub> and a layered structure for rGO. The gas sensing performance was evaluated by exposing the films to hydrogen sulfide (H<sub>2</sub>S) and nitrogen dioxide (NO<sub>2</sub>) at different operating temperatures (150–250&#xa0;°C). The rGO/Co<sub>3</sub>O<sub>4</sub> composite films exhibited enhanced sensitivity, fast response, and rapid recovery times, particularly at an optimal temperature of 200&#xa0;°C. The composite achieved maximum H<sub>2</sub>S sensitivity of 107.8%, with resistance decreasing due to electron transfer from H<sub>2</sub>S adsorption. For NO<sub>2</sub> detection, resistance increased, with the highest sensitivity of 43% at 150&#xa0;°C, attributed to electron withdrawal by NO<sub>2</sub> molecules. These results demonstrate the superior gas sensing performance of rGO/Co<sub>3</sub>O<sub>4</sub> composites compared to pure Co<sub>3</sub>O<sub>4</sub> or rGO, highlighting their potential for high-performance, selective gas sensors. Future work should explore sensor stability, long-term performance, and environmental influences to enhance real-world applicability.</p>

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Temperature-Dependent Gas Sensing Properties of Cobalt Oxide, Reduced Graphene Oxide, and Composite Thin Films Synthesized by Pulsed Laser Ablation

  • 期刊论文

  • 发表日期：

    2025年7月6日

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  • Ghufran Sabbar,
  • Wasan M. Mohammed,
  • Amer Al-Nafiey

摘要

This study explores the synthesis and gas sensing properties of cobalt oxide (Co3O4), reduced graphene oxide (rGO), and rGO/Co3O4 composite thin films, fabricated using pulsed laser ablation (PLA) and drop-casting techniques. The synthesis was performed using a Q-switched Nd:YAG laser (1064 nm, 10 ns pulse width, 4 Hz repetition rate, 140 mJ energy) with laser pulses ranging from 300 to 1000 pulses to control nanoparticle size. FE-SEM analysis revealed a particle size range of 23.9–51 nm, while XRD confirmed a polycrystalline cubic spinel structure for Co3O4 and a layered structure for rGO. The gas sensing performance was evaluated by exposing the films to hydrogen sulfide (H2S) and nitrogen dioxide (NO2) at different operating temperatures (150–250 °C). The rGO/Co3O4 composite films exhibited enhanced sensitivity, fast response, and rapid recovery times, particularly at an optimal temperature of 200 °C. The composite achieved maximum H2S sensitivity of 107.8%, with resistance decreasing due to electron transfer from H2S adsorption. For NO2 detection, resistance increased, with the highest sensitivity of 43% at 150 °C, attributed to electron withdrawal by NO2 molecules. These results demonstrate the superior gas sensing performance of rGO/Co3O4 composites compared to pure Co3O4 or rGO, highlighting their potential for high-performance, selective gas sensors. Future work should explore sensor stability, long-term performance, and environmental influences to enhance real-world applicability.