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Weber J.,University of Bath | Wain A.J.,National Physical Laboratory Teddington TW11 0LW UK | Piili H.,Lappeenranta University of Technology | Matilainen V.-P.,Lappeenranta University of Technology | And 3 more authors.
ChemElectroChem | Year: 2016

Stainless-steel rods were manufactured by laser additive manufacturing (LAM or "3D-printing") from a stainless-steel (316L) powder precursor, and then investigated and compared to conventional stainless steel in electrochemical experiments. The LAM method used in this study was based on "powder bed fusion", in which particles with an average diameter of 20-40μm are fused to give stainless-steel rods of 3mm diameter. In contrast to conventional bulk stainless-steel (316L) electrodes, for 3D-printed electrodes, small crevices in the surface provide residual porosity. Voltammetric features observed for the 3D-printed electrodes immersed in aqueous phosphate buffer are consistent with those for conventional bulk stainless steel (316L). Two chemically reversible surface processes were observed and tentatively attributed to Fe(II/III) phosphate and Cr(II/III) phosphate. Galvanic exchange is shown to allow improved platinum growth/adhesion onto the slightly porous 3D-printed stainless-steel surface, resulting in a mechanically robust and highly active porous platinum deposit with good catalytic activity toward methanol oxidation. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Giusca C.E.,National Physical Laboratory Teddington TW11 0LW UK | Panchal V.,National Physical Laboratory Teddington TW11 0LW UK | Munz M.,National Physical Laboratory Teddington TW11 0LW UK | Wheeler V.D.,Us Naval Research Laboratory Washington 20375Dc United States | And 4 more authors.
Advanced Materials Interfaces | Year: 2015

The sensitivity to water vapour of one-, two-, and three-layer epitaxial graphene (1, 2, and 3LG) is examined in this study. It is unambiguously shown that graphene's response to water, as measured by changes in work function and carrier density, is dependent on its thickness, with 1LG being the most sensitive to water adsorption and environmental concentration changes. This is furthermore substantiated by surface adhesion measurements, which bring evidence that 1LG is less hydrophobic than 2LG. Yet, surprisingly, it is found that other contaminants commonly present in ambient air have a greater impact on graphene response than water vapor alone. This study indicates that graphene sensor design and calibration to minimize or discriminate the effect of the ambient, in which it is intended to operate, are necessary to insure the desired sensitivity and reliability of sensors. The present work will aid in developing models for realistic graphene sensors and establishing protocols for molecular sensor design and development. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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