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4 figures.-- The processed data used in this study are available in the Sussex Figshare database under https://doi.org/10.25377/sussex.21388851. Unprocessed data were available upon request from the corresponding author.-- Supplementary information available., Explosive percolation is an experimentally-elusive phenomenon where network connectivity coincides with onset of an additional modification of the system; materials with correlated localisation of percolating particles and emergent conductive paths can realise sharp transitions and high conductivities characteristic of the explosively-grown network. Nanocomposites present a structurally- and chemically-varied playground to realise explosive percolation in practically-applicable systems but this is yet to be exploited by design. Herein, we demonstrate composites of graphene oxide and synthetic polymer latex which form segregated networks, leading to low percolation threshold and localisation of conductive pathways. In situ reduction of the graphene oxide at temperatures of, This work was funded by the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement no. 642742. A.B.D. acknowledges EPSRC Capital Award EP/S018069/1. W.K.M. and A.B. acknowledge support from Spanish MCIN/AEI under project PID2019-104272RB-C51/AEI/10.13039/501100011033 and the Government of Aragon (DGA) under project “Grupos Consolidados” T03-20R.

5 figures.-- Supplementary information available., Heterostructures of two-dimensional (2D) materials using graphene and MoS2 have enabled both pivotal fundamental studies and unprecedented sensing properties. These heterosystems are intriguing when graphene and MoS2 are interfaced with 2D sheets that emulate biomolecules, such as amino-terminated oligoglycine self-assemblies (known as tectomers). The adsorption of tectomer sheets over graphene and MoS2 modulates the physicochemical properties through electronic charge migration and mechanical stress transfer. Here, we present a systematic study by Raman spectroscopy and tectomer-functionalised scanning probe microscopy to understand mechanical strain, charge transfer and binding affinity in tectomer/graphene and tectomer/MoS2 hybrid structures. Raman mapping reveals distinctive thickness dependence of tectomer-induced charge transfer to MoS2, showing p-doping on monolayer MoS2 and n-doping on multilayer MoS2. By contrast, graphene is n-doped by tectomer independently of layer number, as confirmed by x-ray photoelectron spectroscopy. The interfacial adhesion between the amino groups and 2D materials are further explored using tectomer-functionalised probe microscopy. It is demonstrated here that these probes have potential for chemically sensitive imaging of 2D materials, which will be useful for mapping chemically distinct domains of surfaces and the number of layers. The facile tectomer-coating approach described here is an attractive soft-chemistry strategy for high-density amine-functionalisation of atomic force microscopy probes, therefore opening promising avenues for sensor applications., We would like to acknowledge strategic development funding from the University of Sussex. Additional funding from the Aragon Government is also acknowledged (Grupo de Nanosensores y Sistemas Bioanalíticos (N&SB), ref. E25_20R). [...] This work was also partially supported by a UKRI Future Leaders Fellowship (Grant No. MR/T042664/1).

Talk delivered at the 13th Spanish Conference on Electron Devices, CDE 2021, Sevilla (Spain) 9 June 2021 - 11 June 2021, 171142., This work reports on two-dimensional MoS 2 nanomaterial-based resistive gas sensors and their response to sub-ppm NO 2 concentrations. The sensitive material was prepared by drop-casting MoS 2 nanosheet dispersions on silicon nitride suspended membranes. The sensor response was studied at operating temperatures up to 300 °C. The fabricated sensors provided good responses to NO 2 concentrations as low as 20 ppb at room temperature. The n-type MoS 2 sensing mechanism is here discussed., 10.13039/501100004837-Spanish Ministry of Science and Innovation (Grant Number: PID2019-107697RB-C43)

Liquid-phase exfoliation (LPE) has been shown to be capable of producing large quantities of high-quality dispersions suitable for processing into subsequent applications. LPE typically requires surfactants for aqueous dispersions or organic solvents with high boiling point. However, they have major drawbacks such as toxicity, aggregation during solvent evaporation or the presence of residues. Here, dispersions of molybdenum disulfide in acetone are prepared and show much higher concentration and stability than predicted by Hansen parameter analysis. Aiming to understand these enhanced properties, the nanosheets were characterised using UV-visible spectroscopy, zeta potential measurements, atomic force microscopy, Raman spectroscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and scanning transmission microscopy combined with spatially-resolved electron energy loss spectroscopy. Also, the performance of the MoS2 nanosheets exfoliated in acetone was compared to that of those exfoliated in isopropanol as a catalyst for the hydrogen evolution reaction. The conclusion from the chemical characterisation was that MoS2 nanosheets exfoliated in acetone have an oxygen edge functionalisation, in the form of molybdenum oxides, changing its interaction with solvents and explaining the observed high-quality and stability of the resulting dispersion in a low boiling point solvent. Exfoliation in acetone could potentially be applied as a pretreatment to modify the solubility of MoS2 by edge functionalisation., The SR-EELS studies were conducted at the Laboratorio de Microscopias Avanzadas (LMA) at the Instituto de Nanociencia de Aragon (INA) – Universidad de Zaragoza (Spain). This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement no. 642742 and under the “Graphene Flagship” project grant agreement no. 785219. R. A. also acknowledges the support from the Spanish Ministerio de Economia y Competitividad (MAT2016-79776-P), from the Government of Aragon and the European Social Fund under the project “Construyendo Europa desde Aragon” 2014-2020 (grant number E13_17R). VN wishes to thank the support of SFI (AMBER and I-Form centres, PIYRA and US-Ireland grants) and the ERC CoG (3D2DPrint).

9 Figuras.-- Información complementaria disponible en línea en la página web del editor.-- This document is the unedited Author’s version of a Submitted Work that was subsequently accepted for publication in ACS Applied Nano Materials 1,8, 3903-3912 (2018), copyright © American Chemical Society after peer review. To access the final edited and published work see http://dx.doi.org/10.1021/acsanm.8b00689, Here, we describe the unusual self-assembly of amine-terminated oligoglycine peptides into extended two-dimensional sheets in the presence of silver nanowires. The resulting tectomer sheets are shown to have a strong affinity for the nanowires through a charge-transfer interaction as evidenced by X-ray photoelectron spectroscopy. We show that extended assemblies of metal–peptide hybrids offer additional augmentative functionalities; for instance, the tectomer sheets are hydrophobic in nature and act as a protective layer preventing oxidation and degradation of the nanowires when exposed to atmospheric conditions. Moreover, for silver nanowire percolating networks the presence of the peptide markedly increases the overall electrical conductivity through mechanical squeezing of wire–wire junctions in the network. The peptide–metal interface can be controlled by pH stimulus thus potentially offering new directions where silver nanowire assemblies are used for transparent electrodes ranging from antimicrobial coatings to biosensors., This work was supported by Grant EP/K031562 from the Engineering and Physical Sciences Research Council (EPSRC), ENE2013-48816-C5-5-R project (Plan Nacional de I+D+I, from Spanish Ministerio de Economía y Competitividad MINECO), and H2020-MSCA-ITN-2014 Enabling Excellence project.

5 Figuras.-- Información complementaria disponible en línea en la página web del editor, Carbon nanofoam (CNF) is a low-density, high-surface-area material formed by aggregation of amorphous carbon nanoparticles into porous nanostructures. We report the use of a pulsed infrared laser to prepare CNF from a graphene oxide (GO) target material. Electron microscopy shows that the films consist of dendritic strings that form web-like three-dimensional structures. The conductivity of these structures can be modified by using the CNF as a nanostructured scaffold for gold nanoparticles deposited by sputter coating, controllably increasing the conductivity by up to 4 orders of magnitude. The ability to measure the conductivity of the porous structures allows electrochemical measurements in the environment. Upon decreasing humidity, the pristine CNF exhibits an increase in resistance with a quick response and recovery time. By contrast, the gold-sputtered CNF showed a decrease in resistance, indicating modification of the doping mechanism due to water adsorption. The sensitivity to humidity is eliminated at the percolation threshold of the metal on the CNF., Graham Booth’s work is highly appreciated, helping to set up the deposition system. This work has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Sklodowska-Curie Grant Agreement 642742 as well as from EU H2020 program “Graphene Flagship” (Grant Agreement 696656). R.A. gratefully acknowledges the support from the Spanish Ministerio de Economia y Competitividad (Grant MAT2016-79776-P, (AEI/FEDER, UE)), from the Government of Aragon and the European Social Fund under the project “Construyendo Europa desde Aragon” 2014–2020 (Grant E/26). A.M.B and W.K.M gratefully acknowledge the financial support from Spanish MINECO and AEI (Project ENE2016-79282-C5-1-R and associated EU Regional Development Funds) and the Gobierno de Aragón (Consolidated Group DGA-T66-GCNN and associated EU Social Funds). S.V.-R. thanks Spanish MINECO for her Ph.D. grant (BES2014-068727 and associated EU Social Funds).

Work presented at the 2019 ACS Spring National Meeting, March 28-April 4, 2019 · Orlando, FL., Graphene has attracted enormous interest in the scientific community as the first 2D material with exceptional mechanical, electronic and thermal properties. Pristine Graphene is notoriously difficult to process for macroscale applications, to overcome this many people use graphene oxide (GO) instead. GO is water soluble and easily functionalised and so can be simply processed into various systems. GO lacks the exceptional electronic properties of graphene due to structural disorder, therefore an important area of research is on the reduction of GO, which partly restores the structure and properties of graphene. Various techniques have been developed to perform the reduction step. We report a simple approach for preparing conductive Polymer Latex-rGO composites by using a latex-assembly method. After a treatment in the oven at low T, we can reduce the GO in situ. We make use of the inherent GO properties to optimise the aqueous composite fabrication, which is scalable and adaptable, and then restore conductivity with a simple, low temperature, heating step; opening up pathways to tunable electronic composite materials on a large scale.