The development of vapor sensors with tunable sensitivity and selectivity is highly desirable because of the manifold applications ranging from air quality monitoring to food control. The design of such sensors remains, however, a great challenge. Here, we address this challenge by intercalating primary and tertiary alkylamines with varying alkyl chain lengths into H3Sb3P2O14 nanosheet-based Fabry-Pérot interference sensors. As the sensors are photonic in nature, the different amines can be distinguished based on their intercalation time and optical shift. Since the amines are protonated during intercalation and therefore trapped, this allows us to use amine modification as the basis for creating optical sensors. Intercalation of different amines gradually and widely tunes the sensor’s sensitivity and selectivity to various analytes. This adjustment of sensing properties allows us to construct a sensor array on a single chip, which can distinguish different volatile organic compounds. The color change of this sensor array upon exposure to solvent vapors can be tracked with the naked eye, making this system a promising platform for the high-fidelity identification of volatile compounds. The sensor design protocol presented herein is straightforward and robust and can be transferred to other nanosheet-based devices for the rational tuning of their vapor-sensing properties and beyond.

Reversible post-synthetic modification of H3Sb3P2O14 nanosheet-based thin films by applying a facile two-step amine intercalation over the vapor phase.

1D photonic crystals (1DPCs) are well known from a variety of applications ranging from medical diagnostics to optical fibers and optoelectronics. However, large-scale application is still limited due to complex fabrication processes and bottlenecks in transferring 1DPCs to arbitrary substrates and pattern creation. These challenges were addressed by demonstrating the transfer of millimeter-to centimeter-scale 1DPC sensors comprised of alternating layers of H 3 Sb 3 P 2 O 14 nanosheets and TiO 2 nanoparticles based on a non-invasive chemical approach. By depositing the 1DPC on a sacrificial layer of lithium tin sulfide nanosheets and hydrophobizing only the 1DPC by intercalation of n-octylamine via the vapor phase the 1DPC can be detached from the substrate by immersing the sample in water. Upon exfoliation of the hydrophilic sacrificial layer, the freestanding 1DPC remains at the water-air interface. In a second step, it can be transferred to arbitrary surfaces such as curved glass. In addition, the transfer of patterned 1DPCs is demonstrated by combining the sacrificial layer approach with area-resolved intercalation and etching. The fact that the sensing capability of the 1DPC is not impaired and can be modified after transfer renders this method a generic platform for the fabrication of photonic devices.