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Palladium nanoparticles (PdNPs) have been synthesized using n-alkylamines (C n -NH 2 ) as stabilizing ligands. The NP size and distribution were controlled by varying the initial mole ratio of PdCl 2 /C n -NH 2 and carbon chain lengths of C n -NH 2 including hexylamine (C 6 -NH 2 ), dodecylamine (C 12 -NH 2 ), and octadecylamine (C 18 -NH 2 ). The average PdNP sizes were 20 ( 2.0, 6.0 ( 0.8, 5.6 ( 0.8, 6.5 ( 0.9, and 5.2 ( 0.8 nm prepared with 1:7 PdCl 2 /C 6 -NH 2 , 1:7 PdCl 2 /C 12 -NH 2 , 1:7 PdCl 2 /C 18 -NH 2 , 1:5 PdCl 2 /C 18 -NH 2 , and 1:9 PdCl 2 /C 18 -NH 2 , respectively. The particle size decreased with the increase in the carbon chain length of C n -NH 2 . The as-synthesized n-alkylamine stabilized PdNPs (C n -NH 2 -PdNPs) were fully characterized by transmission electron microscopy, X-ray powder diffraction, UV-visible absorption spectroscopy, infrared (IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), proton nuclear magnetic resonance ( 1 H NMR) spectroscopy, thermogravimetric analysis, graphite furnace atomic absorption spectrometry, and mass spectrometry. The interaction of C 18 -NH 2 with PdNPs was verified by IR, XPS, and 1 H NMR spectra, demonstrating that the amine functionalities were successfully linked to the Pd core surfaces. The PdNPs are soluble and stable in apolar solvents such as benzene, chloroform, n-hexane, and toluene. The electrochemical reactions between CH 4 and C n -NH 2 -PdNPs on Pd electrodes were studied by cyclic voltammetry and chronoamperometry. These PdNPs reacted readily and produced good response to CH 4 at ambient conditions. The sensitivity to CH 4 depends on the PdNPs prepared from various n-alkyl chain lengths of C n -NH 2 and also the mole ratio of PdCl 2 /C n -NH 2 . It was determined that PdNPs synthesized from 1:7 PdCl 2 /C 18 -NH 2 displayed the best electrocatalytic oxidization of CH 4 . The C 18 -NH 2 -PdNP (5.6 nm) modified Pd electrode could be used repeatedly and had a stable and reproducible response to CH 4 .

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Pushed over the edge: Proton-transfer coupled O(2) reduction catalysed by cobalt phthalocyanine ([CoPc]) was studied at the water/1,2-dichloroethane (DCE) interface (see figure). This system represents a new model of molecular electrocatalysis with the proton transfer controlled by the Galvani potential difference and the electron transfer by the molecular properties of the catalyst and electron donor.

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Electrochemiluminescence (ECL) imaging provides a superior approach to achieve array detection because of its ability for ultrasensitive multiplex analysis. In this paper, we reported a novel ECL imaging biosensor array modified with an enzyme/carbon nanotubes/chitosan composite film for the determination of glucose, choline and lactate. The biosensor array was constructed by integrating a patterned indium tin oxide (ITO) glass plate with six perforated poly(dimethylsiloxane) (PDMS) covers. ECL is generated by the electrochemical reaction between luminol and hydrogen peroxide that is produced by the enzyme catalysed oxidation of different substrates with molecular oxygen, and ECL images were captured by a charge-coupled device (CCD) camera. The separated electrochemical micro-cells enabled simultaneous assay of six samples at different concentrations. From the established calibration curves, the detection limits were 14 μM for glucose, 40 μM for lactate and 97 μM for choline, respectively. Moreover, multicomponent assays and cross reactivity were also studied, both of which were satisfied for the analysis. This biosensing platform based on ECL imaging shows many distinct advantages, including miniaturization, low cost, and multi-functionalization. We believe that this novel ECL imaging biosensor platform will have potential applications in clinical diagnostics, medicine and food inspection.

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