Anodic dissolution growth of metal-organic framework HKUST-1 monitored:Via in situ electrochemical atomic force microscopy

In situ electrochemical atomic force microscopy (ec-AFM) is utilised for the first time to probe the initial stages of metal-organic framework (MOF) coating growth via anodic dissolution. Using the example of the Cu MOF HKUST-1, real time surface analysis is obtained that supports and verifies many of the reaction steps in a previously proposed mechanism for this type of coating growth. No evidence is observed however for the presence or formation of Cu2O, which has previously been suggested to be both key for the formation of the coating and a potential explanation for the anomalously high adhesion strength of coatings obtained via this methodology. Supporting in situ electrochemical Raman spectroscopy also fails to detect the presence of any significant amount of Cu2O before or during the coating's growth process

Fabrication and Mechanical Performance of Graphene Nanoplatelet/Glass Fiber Reinforced Polymer Hybrid Composites

From Frontiers via Jisc Publications RouterHistory: collection 2021, received 2021-09-09, accepted 2021-10-20, epub 2021-11-16Publication status: PublishedGlass fiber reinforced polymer (GFRP) composites are promising alternatives for the traditional carbon steel pipes used in the oil and gas industry due to their corrosion and chemical resistance. However, the out-of-plane mechanical properties of GFRPs still need further improvement to achieve this goal. Hence, in this work, two methods combining either vacuum mixing or spray coating with vacuum-assisted resin infusion were studied to fabricate graphene nanoplatelet (GNP)/GFRP hybrid composites. The former method resulted in a severe filtering effect, where the GNPs were not evenly distributed throughout the final composite, whereas the latter process resulted in a uniform GNP distribution on the glass fabrics. The addition of GNPs showed no modest contribution to the tensile performance of the GFRP composites due to the relatively high volume and in-plane alignment of the glass fibers. However, the GNPs did improve the flexural properties of GFRP with an optimal loading of 0.15 wt% GNPs, resulting in flexural strength and modulus increases of 6.8 and 1.6%, respectively. This work indicates how GNPs can be advantageous for out-of-plane mechanical reinforcement in fiber-reinforced composites

The Modified Liquid‐Liquid Interface: The Effect of an Interfacial Layer of MoS 2 on Ion Transfer

From Wiley via Jisc Publications RouterHistory: received 2021-06-15, rev-recd 2021-08-08, pub-electronic 2021-10-28Article version: VoRPublication status: PublishedFunder: Ministry of Education, Saudi ArabiaFunder: EPSRC; Id: http://dx.doi.org/10.13039/501100000266; Grant(s): EP/R023034/1Abstract: MoS2 nanosheets have been assembled at the water|1,2‐dichlorobenzene (DCB) interface into uniform films, and the ion‐transfer properties investigated by voltammetry at the interface between immiscible electrolyte solutions. Remarkably, interfacial MoS2 films were found to enhance the simple and facilitated transfer of cationic species while restricting the transport of anionic species. The enhancement is attributed to a localised increase in the cationic concentration at the interface due to the adsorption onto the negatively charged surface of the exfoliated MoS2 nanosheets. Size‐selectivity for the cationic species was also recognized as a feature of such films. Characterisation of the interfacial film's structure revealed the inclusion of multiple emulsified droplets stabilised by MoS2, where the droplet number and size depend on the concentration of the MoS2 dispersion. Besides increasing the interfacial corrugation and area, the emulsified droplets are believed to influence the mass transport mechanism across the interface. Cyclic voltammetric measurements of saturated films suggested a capillary‐like structure of these films. While the capillaries/nanochannels allow them to have a degree of size‐selectivity that depends on the thickness/density of the film, they also affect the diffusion zones towards and away from the interface. Consequently, steady‐state conditions of mass transport similar to those found in solid‐state supported micro‐ITIES are observed in these nanofilms

Electrically Conductive 2D Material Coatings for Flexible & Stretchable Electronics: A Comparative Review of Graphenes & MXenes

There is growing interest in transitioning electronic components and circuitry from stiff and rigid substrates to more flexible and stretchable platforms, such as thin plastics, textiles, and foams. In parallel, the push for more sustainable, biocompatible, and cost-efficient conductive inks to coat these substrates, has led to the development of formulations with novel nanomaterials. Among these, 2D materials, and particularly graphenes and MXenes, have received intense research interest due to their increasingly facile and scalable production, high electrical conductivity, and compatibility with existing manufacturing techniques. They enable a range of electronic devices, including strain and pressure sensors, supercapacitors, thermoelectric generators, and heaters. These new flexible and stretchable electronic devices developed with 2D material coatings are poised to unlock exciting applications in the wearable, healthcare and Internet of Things sectors. This review has surveyed key data from more than 200 articles published over the last 6 years, to provide a quantitative analysis of recent progress in the field and shade light on future directions and prospects of this technology. We find that despite the different chemical origins of graphenes and MXenes, their shared electrical properties and 2D morphology, guarantee intriguing performance in end applications, leaving plenty of space for shared progress and advancements in the future

Interlayer and interfacial stress transfer in hBN nanosheets

From IOP Publishing via Jisc Publications RouterHistory: received 2021-03-18, revised 2021-06-03, accepted 2021-06-16, oa-requested 2021-06-17, epub 2021-06-30, open-access 2021-06-30, ppub 2021-07Publication status: PublishedFunder: Henry Royce Institute; doi: http://dx.doi.org/10.13039/100016128Funder: China Scholarship Council; doi: http://dx.doi.org/10.13039/501100004543Abstract: Stress transfer has been investigated for exfoliated hexagonal boron nitride (hBN) nanosheets (BNNSs) through the use of Raman spectroscopy. Single BNNSs of different thicknesses of up to 100 nm (300 layers) were deposited upon a poly(methyl methacrylate) (PMMA) substrate and deformed in unixial tension. The Raman spectra from the BNNSs were relatively weak compared to graphene, but the in-plane E2g Raman mode (the G band) could be distinguished from the spectrum of the PMMA substrate. It was found that G band down-shifted during tensile deformation and that the rate of band shift per unit strain decreased as the thickness of the BNNSs increased, as is found for multi-layer graphene. The efficiency of internal stress transfer between the different hBN layers was found to be of the order of 99% compared to 60%–80% for graphene, as a result of the stronger bonding between the hBN layers in the BNNSs. The reduction in bandshift rate can be related to the effective Young’s modulus of the 2D material in a nanocomposites and the findings show that it would be expected that even 100 layer BNNSs should have a Young’s modulus of more than half that of hBN monolayer. Interfacial stress transfer between a single hBN nanosheet and the PMMA substrate has been evaluated using shear lag theory. It is found that the interfacial shear stress between the BNNS and the substrate is of the order of 10 MPa, a factor of around 4 higher than that for a graphene monolayer. These findings imply that BNNSs should give better mechanical reinforcement than graphene in polymer-based nanocomposites as a result of good internal interlayer stress transfer within the nanosheets and better interfacial stress transfer to the polymer matrix

Effect of graphene nanoplatelets on the mechanical and gas barrier properties of woven carbon fibre/epoxy composites

From Springer Nature via Jisc Publications RouterHistory: received 2021-05-14, accepted 2021-08-14, registration 2021-08-23, pub-electronic 2021-09-05, online 2021-09-05, pub-print 2021-12Publication status: PublishedFunder: Engineering and Physical Sciences Research Council; doi: http://dx.doi.org/10.13039/501100000266; Grant(s): EP/K016946/1Abstract: Carbon-fibre-reinforced polymer (CFRP) composites are promising materials for non-metallic pipe applications in the oil and gas industry owing to their high corrosion resistance, specific strength and stiffness. However, CFRP has poor gas barrier performance meaning that a liner has to be inserted. Graphene-based nanomaterials have been demonstrated to improve gas barrier properties in thermoplastic polymers, and thus, a CFRP–graphene hybrid composite could provide an alternative to lined pipes. In this work, a method combining spray coating with vacuum-assisted resin infusion was developed to fabricate CFRP hybrid composites with preferred in-plane aligned graphene nanoplatelets. Tensile and flexural properties, as well as CO2 gas permeability, were evaluated. It was illustrated that both tensile and flexural properties performed better under relatively low GNP loadings (< 0.2 vol%), while gas barrier property was significantly improved with the increasing GNP loadings which fits the Nielsen model with an effective GNP aspect ratio of 350. Graphical abstract

Graphene-enabled adaptive infrared textiles

Interactive clothing requires sensing and display functionalities to be embedded on textiles. Despite the significant progress of electronic textiles, the integration of optoelectronic materials on fabrics remains as an outstanding challenge. In this Letter, using the electro-optical tunability of graphene, we report adaptive optical textiles with electrically controlled reflectivity and emissivity covering the infrared and near-infrared wavelengths. We achieve electro-optical modulation by reversible intercalation of ions into graphene layers laminated on fabrics. We demonstrate a new class of infrared textile devices including display, yarn, and stretchable devices using natural and synthetic textiles. To show the promise of our approach, we fabricated an active device directly onto a t-shirt, which enables long-wavelength infrared communication via modulation of the thermal radiation from the human body. The results presented here provide complementary technologies which could leverage the ubiquitous use of functional textiles

Black Phosphorus with Near-Superhydrophic Properties and Long-Term Stability in Aqueous Media

Black phosphorus is a two-dimensional material that has potential applications in energy storage, high frequency electronics and sensing, yet it suffers from instability in oxygenated and/or aqueous systems. Here we present the use of a polymeric stabilizer which prevents the degradation of nearly 68% of the material in aqueous media over the course of ca. 1 month