Percolating metallic structures templated on laser-deposited carbon nanofoams derived from graphene oxide: applications in humidity sensing
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). ; Peer reviewed