Au25 Nanoclusters Incorporating Three-Dimensionally Ordered Macroporous In2O3 for Highly Sensitive and Selective Formaldehyde Sensing

Detection of formaldehyde (FA) in the atmosphere is of significant importance because exposure to FA may cause serious health problems such as sick-house syndrome, leukemia, and cancer. Modifying metal oxide semiconductors (MOSs) with noble metal nanoparticles (NPs) is an efficient method to enhance FA-sensing properties. Herein, a series of Au-25 nanocluster (NC)-decorated three-dimensionally ordered macroporous In(2)O(3)materials (Au-25/3DOM In2O3) is created, and the loading amount of Au-25 NCs was optimized based on FA responses. To reveal the effect of gold size on FA responses, we constructed Au-144-NC-loaded 3DOM In2O3 and Au NP (2.9 nm)-modified 3DOM In2O3 and compared their gas-sensing properties with the optimal Au-25/3DOM In2O3. The results show that in comparison with its counterparts, the optimal Au-25/3DOM In2O3 presents higher sensitivity, shorter response/recovery times, better selectivity, and excellent reproducibility. More attractively, the responses to FA are dependent on the size of Au particles loaded on In2O3. We suggest that the enhanced FA responses for the optimal material are mainly attributed to the electronic and chemical-sensitization effects of Au-25 NCs, and the size-dependent effect of FA responses is ascribed to the size of Au NPs affecting the formation of oxygen-adsorbing species. This work provides an efficient way for fabricating noble metal NP-loaded MOSs with tunable gas-sensing properties.

Automated summary

In this study, a series of Au-25 nanocluster-decorated three-dimensionally ordered macroporous In2O3 materials were created to enhance formaldehyde (FA) sensing properties. The optimal material showed higher sensitivity, shorter response/recovery times, better selectivity, and excellent reproducibility compared to its counterparts. The enhanced FA responses were mainly attributed to the electronic and chemical-sensitization effects of Au-25 nanoclusters, and the size-dependent effect of FA responses was ascribed to the size of Au nanoparticles affecting the formation of oxygen-adsorbing species.