Selective Discrimination between CO and H₂ with Copper-Ceria-Resistive Gas Sensors

The production of hydrogen and the utilization of biomass for sustainable concepts of energy conversion and storage require gas sensors that discriminate between hydrogen (H₂) and carbon monoxide (CO). Mesoporous copper-ceria (Cu-CeO₂) materials with large specific surface areas and uniform porosity are prepared by nanocasting, and their textural properties are characterized by N₂ physisorption, powder XRD, scanning electron microscopy, transmission electron microscopy, and energy-dispersive X-ray spectroscopy. The oxidation states of copper (Cu⁺, Cu²⁺) and cerium (Ce³⁺, Ce⁴⁺) are investigated by XPS. The materials are used as resistive gas sensors for H₂ and CO. The sensors show a stronger response to CO than to H₂ and low cross-sensitivity to humidity. Copper turns out to be a necessary component; copper-free ceria materials prepared by the same method show only poor sensing performance. By measuring both gases (CO and H₂) simultaneously, it is shown that this behavior can be utilized for selective sensing of CO in the presence of H₂.