Bimetallic AuPd Alloy Nanoparticles Decorated on Macroporous WO3 Supports for Selective Detection of Acetone

Three-dimensional ordered macroporous (3DOM) metal-oxide-based materials have received much attention in the field of gas sensing for their potential in breath acetone analysis. The major challenge of metal-oxide-based sensors for analyzing acetone from exhalation is their poor selectivity in the complex mixture of breath. Functionalizing of sensitive materials by noble metal nanoparticles (NPs) is one of the efficient methods to improve gas sensing selectivity, but noble metal NPs are prone to aggregation at the working temperature. To address these issues, we herein have constructed a series of AuPd/WO3 materials by depositing bimetallic AuPd alloy NPs on the surface of 3DOM WO3 supports. The amount of AuPd NP content and Au/Pd molar ratio are optimized on the basis of acetone responses. The sensor based on the optimal AuPd alloy NP-decorated 3DOM WO3 (AuPdW) exhibits high responses to trace acetone with rapid response/recovery speeds. Besides, the AuPdW sensor presents excellent acetone selectivity and good reproducibility. More attractively, the responses of the sensor to acetone exhibit no noticeable decline over 8 weeks, indicating good long-term stability of the synthesized material. We suggest that the improved responses and excellent selectivity to acetone are ascribed to the synergistic effect of electronic sensitization and chemical sensitization of AuPd alloy NPs. The good long-term stability of AuPdW is attributed to the steric hindrance effect of 3DOM structure to AuPd NPs.