Highly dispersed Pt nanoparticles on hierarchical titania nanoflowers with {010} facets for gas sensing and photocatalysis

Efficient metal oxides-based gas sensing materials and photocatalytic materials require proper morphology, surface and interface structure designing. In this work, highly dispersed Pt nanoparticles with controllable sizes were decorated on different TiO2 (hierarchical TiO2 nanoflowers with {010} facets and TiO2 nanosheets with {001} facets). Their gas sensing and photocatalytic degradation performance were studied. It was demonstrated that both the acetone sensing and methyl orange photocatalytic degradation performance were significantly enhanced by decorating Pt nanoparticles on the hierarchical TiO2 nanoflowers with {010} facets, while Pt nanoparticles decorated on the TiO2 nanosheets with {001} facets had little contribution to the improved performance. The discrepancy in gas sensing and photocatalytic activity of Pt/TiO2 heterojunctions were related to the differential electronic interaction between Pt and different crystal facets, which was confirmed by the density functional theory calculations. Moreover, an interesting transformation from n- to p-type acetone sensing behavior with the increase in Pt content was found, which presented a promising way for gas discrimination. These findings not only shed light on the designing of efficient gas sensing and photocatalytic materials through the synergistic effect of crystal facets engineering, hierarchical structures modulation and facet-selective deposition of Pt nanoparticles, but also deepen the knowledge of noble metal/metal oxides interfacial interactions for high-activity gas sensing and photocatalytic reaction.