Co-PBA MOF-derived hierarchical hollow Co3O4@NiO microcubes functionalized with Pt for superior H2S sensing

Abstract The design and synthesis of hierarchical hollow microcubes are demonstrated as a sensing material for H2S gas detection. The hierarchical hollow microcubes are functionalized by Pt catalysts, assembled from the hierarchical hollow Co3O4 microcubes and coated with nickel oxide nanoplates. The template-engaged synthesis of Co-PBA@Ni(OH)2 microcubes is an etching-deposition-growth hydrothermal process. The gas sensing performances of the sensors based on pure Co3O4 microcubes, pure NiO, Co3O4@NiO microcubes, Co3O4@Pt microcubes, NiO@Pt and Co3O4@NiO@Pt microcubes are systematically investigated. Benefitting from the synergistic effects of the diverse compositions, the advantages of the hierarchical hollow microstructure, a higher surface area of 65.5 m2/g compared with pure Co-PBA microcubes (4.0 m2/g), the p-pheterojunction between Co3O4/NiO, the Schottky barrier amongst NiO/Pt as well as the efficient catalytic activity of Pt, the gas sensors based on Co3O4@NiO-2.0@Pt3.0 microcubes with Pt at 3.0 wt% manifest boosted selectivity, together with enhanced sensing responses (∼250.0 towards 100 ppm H2S) at the optimal working temperature of 200 °C. The response is nearly 78-fold greater than that of the devices based on pure Co3O4 (3.2). Additionally, Pt can dramatically enhance the selectivity to H2S sensors. The enhanced sensing performance of the sensors based on Co3O4@NiO-2.0@Pt3.0 microcubes can also be attributed to the chemical and electronic sensitization of Pt doping as well as the high resistance.