Dual functionalization of Co3O4 and Pd synergistically promotes the hydrogen sensing properties of In2O3 sensor

Hydrogen sensors offer a promising technology for inchoate warning of lithium battery thermal runaway. However, further exploration is still needed to enhance their gas-sensing properties. In this study, Co₃O₄ dodecahedrons and Pd nanoparticles-embedded In₂O₃ microtubes were synthesized using the MIL-68@ZIF-67 template and chemical reduction method. As a result, Co₃O₄ dodecahedrons are equably anchored on the In₂O₃ microtubes, and Pd nanoparticles with different contents are loaded on the In₂O₃@Co₃O₄, forming In₂O₃@Co₃O₄@Pd composite microtubes. The sensor based on In₂O₃@Co₃O₄@Pd with a Pd loading of 0.40 wt% achieves a response of 4.47 and 2.85 toward 20 ppm H₂ at 210 ^oC and 80 ^oC, respectively, whereas the sensors based on bare In₂O₃ and In₂O₃@Co₃O₄ are unresponsive at these two temperatures. Moreover, fast response time (4.5 s), good selectivity and reproducibility, as well as a wide concentration detection range (0.5~1000 ppm) are also obtained. The one-dimensional (1D) microstructure with a high length-to-diameter ratio affords abundant tightly connected n-p heterojunctions between In₂O₃ and Co₃O₄, and the intense interaction between Pd and In₂O₃@Co₃O₄ increases the content of oxygen vacancies, which jointly boost the H₂-sensing properties. The obtained In₂O₃@Co₃O₄@Pd composite has a promising application in real-time H₂ detection.