Pd- and PdO-Decorated TiO2 Nanospheres: Hydrogen Sensing Properties under Visible Light Conditions at Room Temperature

Abstract

As a promising sustainable and clean energy source for the future, hydrogen plays an important role. Due to its high flammability and the explosive nature of hydrogen gas, it is crucial to employ reliable sensors that can detect the presence of hydrogen gas in air at room temperature (RT). By utilizing light, the working temperature of such gas sensors can be reduced whilst simultaneously enhancing sensing performance. In this study, sensors have been fabricated that introduces nano-Schottky junctions (Pd–TiO2) via a facile chemical method and p–n heterojunctions (PdO–TiO2), through both chemical and hydrothermal methods, with a mean Pd nanoparticle (NP) diameter of 4.98 ± 0.49 nm and 4.29 ± 0.45 nm, respectively. The hydrothermally treated Pd-decorated TiO2 nanosphere (HPT NS) shows a response of 100.88% toward 500 ppm hydrogen with a faster response and recovery (77 s and 470 s, respectively). Meanwhile, hydrothermally untreated Pd-decorated TiO2 (PT) NSs show a response of 100.29% with slow response and recovery times (240 s and 3146 s, respectively) at 30 °C under 565 nm visible light and a bias of 500 mV. The experimental results confirm that introducing both metallic Pd and PdO onto the TiO2 NSs open a novel approach for detecting hydrogen gas through light-induced sensing at room temperature using low voltage bias.