Xl30 sfeg sem

An FEI Phillips XL30 SFEG SEM was used in the Electron Microscopy Suite in the Cavendish Laboratory, University of Cambridge. Powder X-ray diffraction (XRD) analysis was performed using a PANalytical BV X'Pert Pro X-ray diffractometer in the Department of Chemistry, University of Cambridge. XPS analysis was performed at the NEXUS XPS facility at Newcastle University. XPS spectra were calibrated to the C 1s signal at 284.8 eV. Quantification of Ni and Ru on the electrodes via ICP-OES (PerkinElmer Optima 2100 DV spectrometer) was carried out at the Department of Geography, University of Cambridge. High-resolution ATR-IR spectra were recorded on a Thermo Scientific Nicolet iS 50 FT-IR spectrometer with an ATR unit. UV-vis absorption spectra of electrodes were recorded in transmission mode in air, and UV-vis solution spectra were recorded in a quartz glass cuvette (1 cm path length) with a Varian Cary 50 UV-vis spectrophotometer. Fluorescence emission spectra of RuP3 in Na₂SO₄ (0.1 M, pH 3) were measured with an Edinburgh Instruments FS5 spectrofluorometer.

For better specimen handling for processing and examination in an SEM, plastic coverslips were used as growth substrate for NTHi biofilms; hence, biofilms were prepared in 20×100 mm tissue culture-treated polystyrene dishes (BD Biosciences, Bedford, MA, USA) with Thermanox plastic coverslips (Nalgene Nunc International, Rochester, NY, USA) placed at the bottom. Then, as previously described [22] , biofilms on coverslips were fixed by plunge-freezing in liquid propane, freeze-substituted with ethanol, gradually warmed to 4°C, and critical point dried. The dried biofilms were mounted on a specimen stub, sputter coated in argon with a 18 nm-layer of platinum and examined in the XL 30 SFEG SEM operating at 5 kV in the secondary electron mode (FEI Company, Hillsboro, OR, USA). Biofilm thickness estimates were obtained from regions where the biofilm profile was visible.