MOF-derived Ag_0.16/In_1.95Pr_0.05O₃ sensors with ultra-high sensitivity, quick response and excellent selectivity to...

In_1.95Pr_0.05O₃ microtubes are derived from MIL-68, and then Ag nanoparticles are anchored to synthesize Ag_0.16/In_1.95Pr_0.05O₃ microtubes. All results indicate that Pr-doping and Ag-loading greatly affect the gas-sensing performance of In₂O₃ sensor, which In_1.95Pr_0.05O₃ and Ag_0.16/In₂O₃ sensors both exhibit the response value exceeding 900. While Ag_0.16/In_1.95Pr_0.05O₃ sensor exhibits the highest response value of 2438.67 to 10 ppm formaldehyde gas, which is about 20 times higher than that of In₂O₃ sensor (122.59). Furthermore, Ag_0.16/In_1.95Pr_0.05O₃ sensor also displays the lower operating temperature (200 °C), shorter response time (12 s), excellent long-term stability, high selectivity, and anti-humidity for formaldehyde gas. According to DFT methods, the adsorption energies of In₂O₃, In_1.95Pr_0.05O₃, and Ag_0.16/In_1.95Pr_0.05O₃ sensors for formaldehyde are calculated to be -0.47 eV, -0.63 eV, and -0.94 eV, respectively. These highly-improved gas-sensing properties are due to the synergistic effect of Pr-doping and Ag-loading, which includes the increased surface oxygen from Pr-doping, the electronic and chemical sensitization from Ag nanoparticles. The gas-sensing mechanism of Ag_0.16/In_1.95Pr_0.05O₃ sensor provides an effective strategy to achieve an excellent gas sensor for formaldehyde gas.