Bimetallic Au and Pd Nanoparticles Modified WO₃ Nanosheets for Enhancing the Sensitivity and Selectivity of Formaldehyde Assessment in Aquatic Products

Formaldehyde, a common illegal additive in aquatic products, poses a threat to people's health and lives. In this study, a novel metal oxide semiconductor gas sensor based on AuPd-modified WO₃ nanosheets (NSs) had been developed for the highly efficient detection of formaldehyde. WO₃ NS modified with 2.0% AuPd nanoparticles showed a higher response (R_a/R_g = 94.2) to 50 ppm of formaldehyde at 210 °C, which was 36 times more than the pristine WO₃ NS. In addition, the AuPd/WO₃ gas sensor had a relatively short response/recovery time of 10 s/9 s for 50 ppm of formaldehyde at 210 °C, with good immunity to other interfering gases and good stability for formaldehyde. The excellent gas-sensitive performance was attributed to the chemical sensitization of Au, the electronic sensitization of Pd, and the synergistic effect of bimetallic AuPd, which facilitated the recognition and response of formaldehyde molecules. Additionally, the high sensitivity and broad application prospect of the 2.0% AuPd/WO₃ NS composite-based sensor in real sample detection were also confirmed by using the above sensor for the detection of formaldehyde in aquatic products such as squid and shrimp.