Bulk-Processed Plasmonic Plastic Nanocomposite Materials for Optical Hydrogen Detection

Abstract

Conspectus Sensors are ubiquitous, and their importance is only going to increase across many areas of modern technology. In this respect, hydrogen gas (H2) sensors are no exception since they allow mitigation of the inherent safety risks associated with mixtures of H2 and air. The deployment of H2 technologies is rapidly accelerating in emerging energy, transport, and green steel-making sectors, where not only safety but also process monitoring sensors are in high demand. To meet this demand, cost-effective and scalable routes for mass production of sensing materials are required. Here, the state-of-the-art often resorts to processes derived from the microelectronics industry where surface-based micro- and nanofabrication are the methods of choice and where (H2) sensor manufacturing is no exception. In this Account, we discuss how our recent efforts to develop sensors based on plasmonic plastics may complement the current state-of-the-art. We explore a new H2 sensor paradigm, established through a series of recent publications, that combines (i) the plasmonic optical H2 detection principle and (ii) bulk-processed nanocomposite materials. In particular, plasmonic plastic nanocomposite sensing materials are described that comprise plasmonic H2-sensitive colloidally synthesized nanoparticles dispersed in a polymer matrix and enable the additive manufacturing of H2 sensors in a cost-effective and scalable way. We first discuss the concept of plasmonic plastic nanocomposite materials for the additive manufacturing of an active plasmonic sensing material on the basis of the three key components that require individual and concerted optimization: (i) the plasmonic sensing metal nanoparticles, (ii) the surfactant/stabilizer molecules on the nanoparticle surface from colloidal synthesis, and (iii) the polymer matrix. We then introduce the working principle of plasmonic H2 detection, which relies on the selective absorption of H species into hydride-forming metal nanoparticles that, in turn, induces distinct changes in their optical plasmonic signature in proportion to the H2 concentration in the local atmosphere. Subsequently, we assess the roles of the key components of a plasmonic plastic for H2 sensing, where we have established that (i) alloying Pd with Au and Cu eliminates hysteresis and introduces intrinsic deactivation resistance at ambient conditions, (ii) surfactant/stabilizer molecules can significantly accelerate and decelerate H2 sorption and thus sensor response, and (iii) polymer coatings accelerate sensor response, reduce the limit of detection (LoD), and enable molecular filtering for sensor operation in chemically challenging environments. Based on these insights, we discuss the rational development and detailed characterization of bulk-processed plasmonic plastics based on glassy and fluorinated matrix polymers and on tailored flow-chemistry-based synthesis of Pd and PdAu alloy colloidal nanoparticles with optimized stabilizer molecules. In their champion implementation, they enable highly stable H2 sen...

Inert gas condensation made bimetallic FeCu nanoparticles – plasmonic response and magnetic ordering

“…44,45 The localizations of the plasmon peaks are different for the targets and for the nanoparticles due to the type of plasmonic response which is of volume or surface character, respectively. 46 As expected, the intensity trend of the plasmon peak in the reflectance spectra for the targets is the same as observed in the absorbance spectra measured for the nanoparticles.…”

Unlocking Predictive Capability and Enhancing Sensing Performances of Plasmonic Hydrogen Sensors via Phase Space Reconstruction and Convolutional Neural Networks

“…Notably, the magnitude change Δ T of the Pd nanocap array significantly exceeds that of a continuum Pd film of identical thickness, owing to the plasmonic resonance of the nanocap nanostructure. In the absence of Pd, standalone PS microspheres exhibit no spectral change upon hydrogen exposure , while the Pd-polymer interface plays a crucial role in facilitating hydrogen diffusion, which in turn enhances the sensor’s performance. In addition, the influence of the triangular islands on T (λ) is minimal (see Section S1 in the Supporting Information (SI)). , …”

“…This fundamental approach, while vital, has not fully addressed the challenge of accurately predicting hydrogen concentrations across a broad range, a task complicated by the PHSs’ nonlinear response and hysteresis effects. ,, Recognizing these complexities, it is acknowledged that while standard calibration curves provide a basis for prediction, their accuracy can be limited by these sensor characteristics. Efforts aimed at mitigating these effects are mainly focusing on optimizing material and structural designs, such as the use of palladium-based alloys, increase of surface-to-volume ratio through special nanostructures, and application of polymer coatings. − These strategies have brought notable improvements in sensitivity, response time, hysteresis, and selectivity. Despite intensive efforts invested in optimizing the materials and structures, the returns in performance enhancements are often incremental and it could be envisioned that unless there will be a major breakthrough, additional alterations to material and structure designs might offer minimal to no further improvements in the sensor’s performance.…”

A surface passivated fluorinated polymer nanocomposite for carbon monoxide resistant plasmonic hydrogen sensing

“…Inspired by the effectiveness of polymer coatings to protect Pd-based hydrogen sensors from chemical deactivation/poisoning, polymer–metal nanoparticle nanocomposites – plasmonic plastics – have recently emerged as an intriguing alternative that allows to augment the processing toolbox that can be used to fabricate plasmonic devices in general with scalable techniques common in the plastics industry such as melt compounding, extrusion, and fused deposition modeling (FDM) 3D printing, and to prepare 3D printed plasmonic hydrogen sensors. 23–25 Specifically, and as a key advantage, such polymer nanocomposites enable one step processing of the active sensing elements and the protective polymer coating material, as we have demonstrated recently using colloidal Pd or PdAu alloy nanoparticles as plasmonic hydrogen sensing elements, and PMMA or the fluorinated polymer Teflon AF as the polymer matrix (see Fig. 2 for chemical structures).…”

“…2 for chemical structures). [23][24][25] The choice of matrix polymer critically inuences both the response time and poisoning/deactivation resistance. With regard to the response time, semicrystalline polymers such as poly(vinylidene diuoride) (PVDF) would result in too slow sensors.…”