Enhanced hydrogen sensing performances of PdO nanoparticles-decorated ZnO flower-like nanostructures

In this work, PdO nanoparticles-decorated ZnO flower-like nanostructures (PdO/ZnO) were synthesized by a one-step facile hydrothermal route and investigated their performance for hydrogen sensing applications. The structural and morphological characterizations were examined by XRD, FESEM, EDS, TEM, and XPS techniques and confirmed the homogenous decoration of PdO nanoparticles on the surface of ZnO flowers. UV-Vis spectroscopy and photoluminescence (PL) spectroscopy were used to investigate the optical characteristics. The ZnO and PdO/ZnO sensors were explored towards different target gases such as hydrogen (H 2 ), carbon monoxide (CO), nitrogen dioxide (NO 2 ), and ethanol. The concentration range of target gases was 2–100 ppm at an operating temperature range of 200–400 °C. It was concluded that PdO/ZnO flowers sensor showed high sensitivity, a speedy response time (20 s), and recovery time (960 s) towards H 2 at 350 °C in comparison to the ZnO sensor. In addition, the PdO decorated ZnO flowers-based sensor showed high selectivity towards H 2 against CO, NO 2, and ethanol. This enhanced gas-sensing performance of the PdO/ZnO sensor has been attributed to the catalytic effect of PdO nanoparticles, and the formation of the PdO-ZnO p-n heterojunction, and their unique flower-like nanostructures. As a result, our research shows that coating PdO on ZnO flowers is an effective technique to improve hydrogen gas sensing performance and can be employed in various applications. The synergist impact of PdO nanoparticles, the arrangement of the PdO-ZnO p-n heterojunction, and their remarkable blossom-like nanostructures were the significant elements for improved gas-detecting execution of PdO/ZnO sensor. • PdO nanoparticles decorated 3D flower-like ZnO nanostructures are prepared by hydrothermal method. • The sensing response of the PdO/ZnO sensor is 3 times higher than the pure ZnO for hydrogen. • The response time of the PdO/ZnO sensor is only 20 s at 350 °C for 100 ppm H 2 and the detection limit to hydrogen is 2 ppm. • The enhancement in sensing properties is due to formation of PdO-ZnO p-n heterojunction and catalytic effect of PdO nanoparticles. • The flower-like morphology also plays a synergistic role.