Synthesis of Co-Doped In2O3 Hierarchical Porous Nanocubes for High-Performance Hydrogen Sulfide Sensors

Recently, because of the urgent need for safety and health protection, there has been a growing focus on exploring effective and feasible gas sensors based on metal oxide semiconductors (MOSs) for detecting trace levels of hydrogen sulfide (H2S). In this context, a cobalt (Co) doping strategy was proposed to improve the H2S-sensitive properties of In2O3 nanomaterials, enabling them to monitor 1 ppm of H2S at a relatively lower temperature. The Co-doped In2O3 hierarchical porous nanocubes (Co–In2O3 HPNCs) were prepared through a hydrothermal route using In(OH)3 as a precursor. When utilized as a sensing material to detect H2S, the Co–In2O3 HPNCs demonstrated significant enhancements compared to pure In2O3. These enhancements include a reduction in the operating temperature (260 vs 300 °C), a significant increase in response (36.99 vs 12.28 for 20 ppm of H2S), and better selectivity (13.21 vs 3.07 times to ethanol). Even to 1 ppm of H2S, the Co–In2O3 sensor can give a response value of 1.86, highlighting its substantial potential for detecting H2S at the limit of detection (LOD) of 1 ppm. A detailed analysis of the multiple sensitization effects of Co doping reveals that these improved H2S sensing characteristics of Co–In2O3 HPNCs can be primarily traced back to three factors, namely, an increased oxygen vacancy concentration, a narrowing of the bandgap, and an upward shift of the Fermi level.