Chemiresistive detection of H2 at near room temperature by porous In2O3 nanotubes co-sensitized with La-dopant and Pd-modifier

Metal oxide semiconductor (MOS)-based hydrogen (H 2 ) 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 H 2 at near room temperature (50 °C) on In 2 O 3 porous nanotubes (PNTs). The In 2 O 3 PNTs were prepared via a solvothermal method and then sequentially doped with La 3+ 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 In 2 O 3 to La-doped In 2 O 3 (La-In 2 O 3 ) and Pd-decorated La-In 2 O 3 (Pd/La-In 2 O 3 ), the fabricated H 2 sensor showed a higher sensitivity at lower operating temperature. At a near room temperature of 50 °C, the response of the best Pd/La-In 2 O 3 sensor to 50 ppm H 2 was as high as 8.34, increasing about 4.85, 1.20 and 1.15 folds compared to the In 2 O 3 (1.72 at 160 °C), La-In 2 O 3 (6.97 at 150 °C) and Pd/In 2 O 3 (7.24 at 80 °C) sensors, respectively. The sensitization effects and mechanism of La dopant and Pd modifier as well as their synergistic effects were discussed in detail.