Pd Nanoparticles Decorated Hollow TiO₂ Nanospheres for Highly Sensitive and Selective UV-Assisted Hydrogen Gas Sensors

Abstract

Hydrogen (H 2 ) gas has great potential as an energy carrier in the emerging renewable energy market, emitting zero CO 2 . However, its high explosive potential and flammability pose substantial risk across production, storage, transport, and consumption; thus, rapid detection of leaks is essential. In this research, hollow TiO 2 nanospheres (h-TiO 2 NS) with a mean diameter of ∼216 nm are fabricated via a solvothermal method. The TiO 2 NS were then chemically decorated with Pd nanoparticles with ∼3.0 nm diameter (Pd/h-TiO 2 NS). The Pd/h-TiO 2 NS enables permeation by H 2 , maximizing active sites due to their high specific surface area of ∼80 m 2 /g and mesoporous structure with an average pore size of 5.6 nm. The chemiresistive Pd/h-TiO 2 NS sensor shows promising results toward H 2 at 80 °C under 9 V bias and 365 nm UV light with an exceptional response (4.1 for 0.1% H 2 and ∼88 for 1% H 2 ), a response time of 36 s for 0.1% H 2 and 76 s for 1% H 2 , and fast recovery (38 and 39 s for 0.1% and 1% H 2 , respectively). Even under dark conditions, the sensor exhibits a high response (2.3 for 0.1% H 2 and ∼47 for 1% H 2 ) with a response time of 52 s for 0.1% H 2 and 39 s for 1% H 2 and efficient recovery (68 and 39 s for 0.1% and 1% H 2 , respectively). Additionally, a wide range of H 2 concentrations from 50 to 10,000 ppm can be detected under both light and dark conditions. CH 4 or CO 2 does not affect sensor response, NH 3 , NO 2 , or acetone only marginally affects response. Even the influence of humidity is very low. The response remained stable across three months. The results confirm that Pd/h-TiO 2 NS are promising for H 2 sensing and establish a benchmark in this field.