a b s t r a c tScreen printed carbon electrodes (SPCE) were decorated with PdCu bimetallic alloys via a facile coelectrodeposition method to develop disposable non-enzymatic H 2 O 2 sensors. The electrochemical performance of the biosensors was evaluated in terms of selectivity, sensitivity, and stability with a goal of demonstrating that employing a bimetallic PdCu non-enzymatic system can push forward the state of the art in hydrogen peroxide sensing. The physical characterization of the biosensors was conducted using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) techniques. Sensors consisting of PdCu bimetals showed higher sensitivity than Pd/SPCE and Cu/SPCE electrodes toward H 2 O 2 . The fabricated PdCu/SPCE sensors showed a sensitivity of 396.7 A mM −1 cm −2 , a linear range from 0.5 mM to 11 mM, and a low limit of detection (0.7 M) at the applied potential of −0.3 V. The use of relatively low working potential eliminated the interference effect of the common electroactive species (ascorbic acid, uric acid, and glucose) present in a real sample, which are usually a concern for non-enzymatic sensing systems. In addition, the high reproducibility (RSD = 2.5%), and excellent long term stability render PdCu/SPCEs as attractive materials for the construction of disposable enzyme-free H 2 O 2 sensors.

PSS-SiO2 nanoparticle dispersions. Based on these measurements, we demonstrate that these particles are stable when dispersed in propylene carbonate. Using a combination of rheology and dielectric spectroscopy, we show that these stable dispersions facilitate electrical percolation at concentrations below their mechanical percolation threshold, and this percolation is maintained under flow. These results demonstrate the potential for strategies which seek to decouple mechanical and electrical percolation to allow for the development of higher performance conductive additives for slurry based flow batteries.

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In the last couple of years, Pd and its alloys gained considerable interest for non-enzymatic hydrogen peroxide (H2O2) and glucose sensing applications. Although Pd shows lower catalytic activity than Pt, its eco-friendly nature and low cost make it a promising catalyst material for many applications ranging from fuel cells to biosensors. Great effort has been devoted to improve the catalytic activity of Pd using various methods such as preparation of Pd nanostructures with different morphologies and alloy formation with transitional metals. In this work, Pd and PdCu alloys with varying compositions were deposited via a simple electrodeposition method on screen printed carbon electrodes (SPCEs) to fabricate non-enzymatic H2O2 sensors. Our results showed that co-deposition of Pd and Cu improved the electrochemical activity of the prepared electrodes significantly compared to pure Pd decorated SPCEs. The highest electrochemical activity was obtained from PdCu electrodes with (7:3) molar ratio. The sensitivity of this electrode to H2O2 was found to be -390.5 µA mM-1 cm-2 at the working potential of -300 mV (vs. Ag/AgCI). In addition, the electrodes showed a wide linear range of 0.5-6 mM and a low detection limit (0.3 µM).