Abstract

Metal oxide semiconductor (MOS)-based hydrogen (H₂) sensor that can work at room or near room temperature has attracted an increasing concern owing to its potential application in hydrogen storage and utilization. Herein, a co-sensitization strategy by La doping and Pd decoration is proposed to realize the detection of H₂ at near room temperature (50?^oC) on In₂O₃ porous nanotubes (PNTs). The In₂O₃ PNTs were prepared via a solvothermal method and then sequentially doped with La³⁺ and decorated with Pd nanoparticles via an immersion, freeze-drying and calcination route and a chemical reduction method, respectively. The results of gas-sensing measurements indicated that after a compositional evolution from In₂O₃ to La-doped In₂O₃ (La-In₂O₃) and Pd-decorated La-In₂O₃ (Pd/La-In₂O₃), the fabricated H₂ sensor showed a higher sensitivity at lower operating temperature. At a near room temperature of 50?^oC, the response of the best Pd/La-In₂O₃ sensor to 50 ppm H₂ was as high as 8.34, increasing about 4.85, 1.20 and 1.15 folds compared to the In₂O₃ (1.72 at 160?^oC), La-In₂O₃ (6.97 at 150?^oC) and Pd/In₂O₃ (7.24 at 80?^oC) sensors, respectively. The sensitization effects and mechanism of La dopant and Pd modifier as well as their synergistic effects were discussed in detail.