Small or Sharp Edged? Impact of Facets-Controlled Ag{111} Nanoprism on the Gas Sensing Redox Characteristics of WO₃

Recent reports that associate the redox characteristics of metal nanostructures (NSs) merely to their particle size are sceptical and need to examine the intrinsic property that dominates their redox properties. Aiming this, the gas sensing redox characteristics of (i) isotropic Ag nanospheres and (ii) the anisotropic Ag{111} nanoprism are examined by decorating them on the WO₃ surface. As revealed by KPFM measurements, the low work function values of Ag{111} (i.e., 4.09 eV) compared to Ag spheres (4.28 eV) induced a favorable band bending at the WO₃ (4.67 eV) interface and reduced the barrier height by 0.24 eV. Consequently, the activation energy of Ag{111}/WO₃ got reduced to ∼0.51 kJ mol^-1 at 10 ppm of NO₂, boosting its sensor response by 18 folds compared to Ag nanoparticles/WO₃-based devices. These findings highlight that anisotropic growth along Ag{111} facets is more critical than size in influencing the redox properties and plays a dominant role in enhancing the redox characteristics.