Synthesis of Co-Doped InO 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 (HS). In this context, a cobalt (Co) doping strategy was proposed to improve the HS-sensitive properties of InO nanomaterials, enabling them to monitor 1 ppm of HS at a relatively lower temperature. The Co-doped InO hierarchical porous nanocubes (Co-InO HPNCs) were prepared through a hydrothermal route using In(OH) as a precursor. When utilized as a sensing material to detect HS, the Co-InO HPNCs demonstrated significant enhancements compared to pure InO. 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 HS), and better selectivity (13.21 vs 3.07 times to ethanol). Even to 1 ppm of HS, the Co-InO sensor can give a response value of 1.86, highlighting its substantial potential for detecting HS at the limit of detection (LOD) of 1 ppm. A detailed analysis of the multiple sensitization effects of Co doping reveals that these improved HS sensing characteristics of Co-InO 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.