Ce0.8Gd0.2O1.95 based mixed potential gas sensor: AgRu bimetallic co-regulated WO3 for H2 sensing under high temperature

Abstract

Trace detection and early warning of H2 leakage at high temperatures are of great significance in eliminating potential safety risks and ensuring the safety of human life and property. Herein, Ce0.8Gd0.2O1.95-based mixed potential high temperature H2 sensors made of AgRu@WO3 synthesized by photochemical reduction method as the sensing materials are designed and demonstrated. By adjusting the content of Ag in WO3 and the ratio of Ag and Ru, the sensitivity of the sensor is effectively improved and the operating temperature is reduced. The interaction between Ag and WO3 (synergistic hydrogen spillover effect) is the major reason for the sensitivity of sensors to H2. Ru is further introduced with the aim of using its catalytic and dissociative capabilities to make the optimal operating temperature of the sensor well below the deflagration point of H2 (520 °C for Ag@WO3 to 430 °C for AgRu@WO3). At 430 °C, H2 in the range of 2–2000 ppm can be detected by such sensors. The response value to 50 ppm H2 can reach − 79 mV. Analysis using X-Ray Diffractometer (XRD), Scanning Electron Microscope (SEM) and X-ray Photoelectron Spectroscopy (XPS) are performed to explore the formations of AgRu@WO3 and its sensing mechanism. To the best of our knowledge, there are no reports on the use of bimetallic-modified metal oxide sensing materials for Ce0.8Gd0.2O1.95 solid electrolyte sensors in order to simultaneously increase the sensitivity and reduce the operating temperature. This study provides a new reference for subsequent researchers in the selection of sensing materials for solid electrolyte sensors, as well as a new option for accurate and stable detection of H2 at high temperatures.