Raza, M. H.; Crispi, S.; Jozwiak, E.; Frisch, M.; Kraehnert, R.; Schlatmann, R.; Amkreutz, D.; Neri, G.; Pinna, N.: Chemoresistive properties of NiO surface-modified Nb-doped TiO2 mesoporous thin films. RSC Applied Interfaces 3 (2026), p. 95-103
10.1039/D5LF00279F
Open Access Version
Abstract:
Functionalized metal oxide thin films are widely applicable in heterogeneous catalysis and gas sensing due to their distinct electrochemical properties. Given their importance in practical applications, developing a comprehensive understanding of their chemoresistive behavior is essential, which requires the precise engineering of thin-film-based nanostructures. Here, we report the on-chip fabrication of mesoporous Nb-doped titania (NbxTi1−xO2) thin films with template-controlled mesoporosity via dip-coating and subsequent calcination on conductometric transducers. The pore wall surfaces of mesoporous NbxTi1−xO2 films were surface-modified with variable NiO loadings via atomic layer deposition (ALD) to produce NiO-loaded NbxTi1−xO2 thin films (XNiO–NbxTi1−xO2). The NiO loading was controlled by adjusting the number of ALD cycles (X = 5–200). The chemoresistive properties of the synthesized mesoporous Nb−Ti1−xO2 and XNiO–NbxTi1−xO2 thin films were investigated under different environmental conditions, namely oxidizing and reducing gases. The XNiO–NbxTi1−xO2 thin films showed an enhanced response to reducing gases, particularly acetone and ethanol, compared to unloaded mesoporous NbxTi1−xO2. Among them, 5NiO–NbxTi1−xO2, featuring discontinuous NiO-decorated species, exhibits the strongest response to acetone. The superior sensing performance of the on-chip fabricated 5NiO–NbxTi1−xO2 sensor toward acetone is attributed to the high surface area of the mesoporous thin films and surface-modification with NiO species, which enhances the sensing properties through chemical sensitization.