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Nanoplasmonic hydrogen sensors are predicted to play a key role in safety systems of the emerging hydrogen economy. Pd nanoparticles are the active material of choice for sensor prototype development due to their ability to form a hydride at ambient conditions, which creates the optical contrast. Here, we introduce plasmonic hydrogen sensors made from a thermoplastic nanocomposite material, that is, a bulk material that can be molded with standard plastic processing techniques, such as extrusion and three-dimensional (3D) printing, while at the same time being functionalized at the nanoscale. Specifically, our plasmonic plastic is composed of hydrogen-sensitive and plasmonically active Pd nanocubes mixed with a poly­(methyl methacrylate) matrix, and we optimize it by characterization from the atomic to the macroscopic level. We demonstrate melt-processed deactivation-resistant plasmonic hydrogen sensors, which retain full functionality even after 50 weeks. From a wider perspective, we advertise plasmonic plastic nanocomposite materials for application in a multitude of active plasmonic technologies since they provide efficient scalable processing and almost endless functional material design opportunities via tailored polymer–colloidal nanocrystal combinations.

Hydrogen (H 2 ) sensors that can be produced en masse with cost-effective manufacturing tools are critical for enabling safety in the emerging hydrogen economy. The use of melt-processed nanocomposites in this context would allow the combination of the advantages of plasmonic hydrogen detection with polymer technology; an approach which is held back by the slow diffusion of H 2 through the polymer matrix. Here, we show that the use of an amorphous fluorinated polymer, compounded with colloidal Pd nanoparticles prepared by highly scalable continuous flow synthesis, results in nanocomposites that display a high H 2 diffusion coefficient in the order of 10 –5 cm 2 s –1 . As a result, plasmonic optical hydrogen detection with melt-pressed fluorinated polymer nanocomposites is no longer limited by the diffusion of the H 2 analyte to the Pd nanoparticle transducer elements, despite a thickness of up to 100 μm, thereby enabling response times as short as 2.5 s at 100 mbar (≡10 vol. %) H 2 . Evidently, plasmonic sensors with a fast response time can be fabricated with thick, melt-processed nanocomposites, which paves the way for a new generation of robust H 2 sensors.

The improved Hummers' synthesis of graphene oxide (GO) from graphite is investigated to monitor how the functional groups form during the synthesis steps. To achieve these, samples are taken after every preparation step, and analyzed with TG-DTA/MS, FTIR, XRD and SEM-EDX techniques. It was found that the main characteristic mass loss step of GO was around 200 °C, where at first the carboxyl and lactone groups were released, and the evolution of sulphonyl groups followed them right away in a partially overlapping step. It became clear that in the as-prepared acidic GO sample the presence of H 2 SO 4 originating from the reaction solution was still dominant. The functional groups were formed only after washing the as-prepared GO with HCl. The consecutive washing step with distilled water did not alter the functional groups or the thermal properties significantly; however, it made the GO structure more ordered. The reduction of the GO structure back to reduced GO (rGO) resulted in the loss of the functional groups and a graphitic material was obtained back.

Eco-friendly materials with superior thermal insulation and mechanical properties are desirable for improved energy- and space-efficiency in buildings. Cellulose aerogels with structural anisotropy could fulfill these requirements, but complex processing and high energy demand are challenges for scaling up. Here we propose a scalable, nonadditive, top-down fabrication of strong anisotropic aerogels directly from wood with excellent, near isotropic thermal insulation functions. The aerogel was obtained through cell wall dissolution and controlled precipitation in lumen, using an ionic liquid (IL) mixture comprising DMSO and a guanidinium phosphorus-based IL [MTBD][MMP]. The wood aerogel shows a unique structure with lumen filled with nanofibrils network. In situ formation of a cellulosic nanofibril network in the lumen results in specific surface areas up to 280 m 2 /g and high yield strengths >1.2 MPa. The highly mesoporous structure (average pore diameter ∼20 nm) of freeze-dried wood aerogels leads to low thermal conductivities in both the radial (0.037 W/mK) and axial (0.057 W/mK) directions, showing great potential as scalable thermal insulators. This synthesis route is energy efficient with high nanostructural controllability. The unique nanostructure and rare combination of strength and thermal properties set the material apart from comparable bottom-up aerogels. This nonadditive synthesis approach is believed to contribute significantly toward large-scale design and structure control of biobased aerogels.

Abstract.Comparative investigations are reported on poly(N-isopropylacrylamide) (PNIPA) gels of various carbon nanotube (CNT) and graphene oxide (GO) contents synthesized under identical conditions. The kind and concentration of the incorporated carbon nanoparticles (CNPs) influence the swelling and stress-strain behaviour of the composites. Practically independently of the filler content, incorporation of CNPs appreciably improves the fracture stress properties of the gels. The time constant and the swelling ratio of the shrinkage following an abrupt increase in temperature of the swelling medium from 20 to 50°C can be adjusted by selecting both the type and the amount of nanoparticle loading. This offers a means of accurately controlling the deswelling kinetics of drug release with PNIPA systems, and could be employed in sensor applications where fast and excessive shrinkage are a significant drawback. Both CNTs and GO enhance the infrared sensitivity of the PNIPA gel, thus opening a route for the design of novel drug transport and actuator systems. It is proposed that the influence of the CNPs depends more on their surface reactivity during the gel synthesis rather than on their morphology. One of the important findings of this study is the existence of a thermally conducting network in the GO filled gels.

The catalytic performance of multi-walled carbon nanotubes (MWCNTs) with different surface chemistry was studied in the decomposition reaction of H 2 O 2 at various values of pH and temperature. A comparative analysis of experimental and quantum chemical calculation results is given. It has been shown that both the lowest calculated activation energy (~18.9 kJ/mol) and the highest rate cons tant correspond to the N-containing CNT. The calculated chemisorption energy values correlate with the operation stability of MWCNTs. Based on the proposed quantum chemical model it was found that the catalytic activity of carbon materials in electron tran sfer reactions is controlled by their electron donor capability.

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