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Additive manufacturing electrochemistry is an ever-expanding field; however, it is limited to aqueous environments due to the conductive filaments currently available. Herein, the production of a conductive poly(propylene) filament, which unlocks the door to organic electrochemistry and electrosynthesis, is reported. A filament with 40 wt % carbon black possessed enhanced thermal stability, excellent low-temperature flexibility, and high conductivity. The filament produced highly reproducible additive manufactured electrodes that were electrochemically characterized, showing a k 0 of 2.00 ± 0.04 × 10 -3 cm s -1 . This material was then applied to three separate electrochemical applications. First, the electroanalytical sensing of colchicine within environmental waters, where a limit of detection of 10 nM was achieved before being applied to tap, bottled, and river water. Second, the electrodes were stable in organic solvents for 100 cyclic voltammograms and 15 days. Finally, these were applied toward an electrosynthetic reaction of chlorpromazine, where the electrodes were stable for 24-h experiments, outperforming a glassy carbon electrode, and were able to be reused while maintaining a good electrochemical performance. This material can revolutionize the field of additive manufacturing electrochemistry and expand research into a variety of new fields.

Graphite sheet (GS) electrodes are flexible and versatile substrates for sensing electrochemical; however, their use has been limited to incorporate (bio)chemical modifiers. Herein, we demonstrated that a cold (low temperature) CO 2 plasma treatment of GS electrodes provides a substantial improvement of the electrochemical activity of these electrodes due to the increased structural defects on the GS surface as revealed by Raman spectroscopy (I D /I G ratio), and scanning electron microscopy images. XPS analyses confirmed the formation of oxygenated functional groups at the GS surface after the plasma treatment that are intrinsically related to the substantial increase in the electron transfer coefficient (K 0 values increased from 1.46 × 10 -6 to 2.09 × 10 -3 cm s -1 ) and with reduction of the resistance to charge transfer (from 129.8 to 0.251 kΩ). The improved electrochemical activity of CO 2 -GS electrodes was checked for the detection of emerging contaminant species, such as chloramphenicol (CHL), ciprofloxacin (CIP) and sulphanilamide (SUL) antibiotics, at around + 0.15, + 1.10 and + 0.85 V (versus Ag/AgCl), respectively, by square wave voltammetry. Limit of detection values in the submicromolar range were achieved for CHL (0.08 μmol L -1 ), CIP (0.01 μmol L -1 ) and SFL (0.11 μmol L -1 ), which enabled the sensor to be successfully applied to natural waters and urine samples (recovery values from 85 to 119%). The CO 2 -GS electrode is highly stable and inexpensive ($0.09 each sensor) and can be easily inserted in portable 3D printed cells for environmental on-site analyses., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

A rapid and simple method for the amperometric determination of glucose using a nanocomposite film of nickel oxyhydroxide and multi-walled carbon nanotube (MWCNTs) was evaluated. The NiHCF)/MWCNT electrode film was fabricated using the liquid-liquid interface method, and it was used as a precursor for the electrochemical synthesis of nickel oxy-hydroxy (Ni(OH) 2 /NiOOH/MWCNT). The interaction between nickel oxy-hydroxy and the MWCNTs provided a film that is stable over the electrode surface, with high surface area and excellent conductivity. The nanocomposite presented an excellent electrocatalytic activity for the oxidation of glucose in an alkaline medium. The sensitivity of the sensor was found to be 0.0561 μA μmol L -1 , and a linear range from 0.1 to 150 μmol L -1 was obtained, with a good limit of detection (0.030 μmol L -1 ). The electrode exhibits a fast response (150 injections h -1 ) and a sensitive catalytic performance, which may be due to the high conductivity of MWCNT and the increased active surface area of the electrode. Additionally, a minimal difference in the slopes for ascending (0.0561 µA µmol L -1 ) and descending (0.0531 µA µmol L -1 ) was observed. Moreover, the sensor was applied to the detection of glucose in artificial plasma blood samples, achieving values of 89 to 98% of recovery.

Silver materials are known to present excellent properties, such as high electrical and thermal conductivity as well as chemical stability. Silver-based inks have drawn a lot of attention for being compatible with various substrates, which can be used in the production uniform and stable pseudo-reference electrodes with low curing temperatures. Furthermore, the interest in the use of disposable electrodes has been increasing due to the low cost and the possibility of their use in point-of-care and point-of-need situations. Thus, in this work, two new inks were developed using Ag as conductive material and colorless polymers (nail polish (NP) and shellac (SL)), and applied to different substrates (screen-printed electrodes, acetate sheets, and 3D-printed electrodes) to verify the performance of the proposed inks. Measurements attained with open circuit potential (OCP) attested to the stability of the potential of the pseudo-reference proposed for 1 h. Analytical curves for β-estradiol were also obtained using the devices prepared with the proposed inks as pseudo-references electrodes, which presented satisfactory results concerning the potential stability (RSD < 2.6%). These inks are simple to prepare and present great alternatives for the development of pseudo-reference electrodes useful in the construction of disposable electrochemical systems.

Trace amounts of copper decrease significantly the oxidative stability of biodiesel while antioxidants, mostly tert-butylhydroquinone (TBHQ), are commonly introduced to the biofuel to guarantee induction period values within regulatory limits. Hence, a simple method to monitor the most used antioxidant and the most deleterious contaminant in biodiesel can give a fast response on its quality. In this context, this work presents a simple, efficient, low cost and sensitive method for the simultaneous and direct determination of copper and the antioxidant TBHQ in biodiesel. The biodiesel samples were diluted in 90% (v/v) ethanol and 10% (v/v) water containing 0.1 mol L -1 HCl (final concentration) as the supporting electrolyte generating a homogeneous mixture in which Cu(II) and TBHQ were directly detected using the square wave voltammetry (SWV) on a gold working electrode. The presence of biodiesel in the selected electrolyte facilitated the separation of analyte peaks facilitating the treatment of data and quantification. The linear responses for the simultaneous determination were in the range between 5 and 100 μg L -1 and 4.2-81.5 mg L -1 for copper and TBHQ (R > 0.997), respectively. High precision (RSD = 4.0% and 3.9%, n = 20) and limit of detection (LOD) values of 0.31 μg L -1 and 1.0 mg L -1 (0.030 μg g -1 and 0.102 mg g -1 in biodiesel) for Cu(II) and TBHQ, respectively, were obtained. Recovery values between 97% and 104% for both copper and TBHQ were obtained., (Copyright © 2019 Elsevier B.V. All rights reserved.)

This work presents the highly-sensitive detection of 2,4,6-trinitrotoluene (TNT) on reduced graphene oxide/multi-walled carbon nanotube (rGO/MWCNT) nanocomposite sensor. The formation of a thin film of this nanocomposite occurred at the cyclohexane/water immiscible interface of a mixture of MWCNT and rGO in the biphasic solution. The film was transferred to a boron-doped diamond (BDD) electrode for the square-wave voltammetric detection of TNT, which presented improved analytical characteristics in comparison with bare BDD and after modification with precursors. Electrochemical impedance spectroscopy also revealed the faster electron transfer for a redox probe on the nanocomposite modified surface. The synergistic properties of both carbon nanomaterials in the thin film modified surface resulted in a TNT sensor with a detection limit of 0.019 μmol L -1 within a wide linear range (0.5-1100 μmol L -1 ), with superior performance in comparison with other electrochemical sensors produced with carbon nanomaterials. This new material provides great promises for the highly-sensitive detection of other nitroaromatic explosives as well as other analytes. Moreover, the interfacial method enables the production of homogeneous and stable films on large coated areas as well as the large-scale production of electrochemical sensors., (Copyright © 2018 Elsevier B.V. All rights reserved.)

We describe the development of an electrophoresis microchip fabricated by a direct-printing process, based on lamination of printed polyester films with end-channel amperometric detection. The channel structures are defined by polyester (base and cover) and by a toner layer (walls). The polyester-toner devices presented an electroosmotic flow (EOF) magnitude of approximately 10(-5) cm2 V(-1) s(-1), which is generated by a polymeric mixture of the toner and polyester composition. The microelectrodes used for detection were produced combining this laser-printer technology to compact discs. The performance of this device was evaluated by amperometric detection of iodide and ascorbate. The detection limits found were 500 nmol.L(-1) (135 amol) and 1.8 micromol.L(-1) (486 amol) for iodide and ascorbate, respectively.