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•3D printing technology for production of low-cost 3D graphene electrodes.•Electrochemical oxidation/reduction pre-treatments for improvement of the electron transfer kinetics.•3D ...printed electrode for electrocatalytic detection of dopamine.
3D printing has been reported as a remarkable technology for development of electrochemical devices, due to no design constraints, waste minimization and, most importantly, fast prototyping. The use of 3D printed electrodes for electroanalytical applications is still a challenge and demand efforts. In this work, we have developed low-cost and reproducible 3D-printed graphene electrodes for electrocatalytic detection of dopamine. Electrocatalytic features were enhanced after electrochemical pre-treatment. The oxidation and reduction at different potential ranges, in 0.1 mol L−1 phosphate buffer solution (pH = 7.4), are used to modulate the structural and morphological characteristics of the electrodes. Since, the electrochemical properties of the electrodes, including electron transfer kinetic and the electrocatalytic activity, are strongly influenced by electronic properties and the presence of functional groups. Raman spectroscopy, SEM and AFM microscopes and electrochemical techniques were used to characterize the 3D electrodes before and after the electrochemical pre-treatments. Finally, the performances of the 3D-printed graphene electrodes were evaluated towards dopamine sensing. The best performance was achieved by oxidation at + 1.8 V vs. SCE for 900 s and reduction from 0.0 V to -1.8 V vs. SCE at 50 mV s−1. The proposed sensor presented linear response from 2.0 μmol L−1 to 10.0 μmol L−1, with detection limit of 0.24 μmol L−1.
Additive manufacturing or three-dimensional (3D)-printing is an emerging technology that has been applied in the development of novel materials and devices for a wide range of applications, including ...Electrochemistry and Analytical Chemistry areas. This review article focuses on the contributions of 3D-printing technology to the development of electrochemical sensors and complete electrochemical sensing devices. Due to the recent contributions of 3D-printing within this scenario, the aim of this review is to present a guide for new users of 3D-printing technology considering the required features for improved electrochemical sensing using 3D-printed sensors. At the same time, this is a comprehensive review that includes most 3D-printed electrochemical sensors and devices already reported using selective laser melting (SLM) and fused deposition modeling (FDM) 3D-printers. The latter is the most affordable 3D-printing technique and for this reason has been more often applied for the fabrication of electrochemical sensors, also due to commercially-available conductive and non-conductive filaments. Special attention is given to critically discuss the need for the surface treatment of FDM 3D-printed platforms to improve their electrochemical performance. The insertion of biochemical and chemical catalysts on the 3D-printed surfaces are highlighted as well as novel strategies to fabricate filaments containing chemical modifiers within the polymeric matrix. Some examples of complete electrochemical sensing systems obtained by 3D-printing have successfully demonstrated the enormous potential to develop portable devices for on-site applications. The freedom of design enabled by 3D-printing opens many possibilities of forthcoming investigations in the area of analytical electrochemistry.
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•We review the contributions of 3D-printing to fabricate electrochemical sensors.•Different 3D-printing methods are compared highlighting fused deposition modeling (FDM).•Surface treatment and modification with (bio)chemical mediators for improved performance.•Strategies for fabrication of conductive filaments are presented for future applications.•3D-printing of all-in-one electrochemical devices in different designs are assessed.
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•Use of photochemical methods for producing nanocomposite.•Controlling the size of Prussian blue nanocubes in the nanocomposite.•Simultaneous electrochemical detection of ascorbic ...acid, dopamine, and uric acid.
The practical application of Prussian blue (PB) for sensors is still limited due to its electrochemical properties that are dependent on factors such as the low stability at pH close to 7.0, the size and the shape of the material. In this sense, we report a green and facile strategy for one-pot synthesis of reduced graphene oxide/Prussian blue nanocomposites via photochemical method for sensing application. In the proposed method, graphene oxide was reduced simultaneously with the formation of PB nanocubes with controllable size, using sodium nitroprusside as precursor. The nanocomposite is more stable and sensible to electro-reduction of H2O2 when compared to PB at pH 7.4. The observed behavior is due to the ability of graphene to anchor the nanocubes and facilitate the electron transfer between the electrode and PB. Moreover, we also investigated the performance of the nanocomposite for simultaneous detection of ascorbic acid (AA), dopamine (DA) and uric acid (UA). The sensor presented limits of detection of 34.7μmolL−1, 26.2μmolL−1, 8.0μmolL−1, for AA, DA, and UA, respectively.
We demonstrate that polylactic acid (PLA)/graphene additive manufactured (3D‐printed) electrodes (Gr/AMEs) electrodeposited with Ni−Fe (oxy)hydroxide can efficiently catalyse the oxygen evolution ...reaction (OER). X‐ray photoelectron spectroscopy (XPS) depth profiling combined with Atomic Force Microscopy (AFM) and Tip Enhanced Raman Spectroscopy (TERS) deduced the composition and depth of the Ni−Fe (oxy)hydroxide layer. The composition of the resulting electrocatalytic surfaces are tailored through altering the concentrations of nickel and iron within the electrodeposited solutions, which give rise to optimised AMEs OER performance (within 0.1 M KOH). The optimal OER performance was observed from a Ni−Fe (oxy)hydroxide with a 10 % content of Fe, which displayed an OER onset potential and overpotential of+1.47 V (vs. RHE) and 519 mV, respectively. These values arecomparable to that of polycrystalline Iridium (+ 1.43 V (vs. RHE) and ca. 413 mV), as well as being significantly less electropositive than a bare/unmodified AME. This work is essential for those designing, fabricating and modulating additive manufactured electrodes.
Advanced electrodes: Polylactic acid/graphene additive manufactured electrodes (Gr/AMEs) electrodeposited with Ni−Fe (oxy)hydroxide can efficiently catalyze the oxygen evolution reaction.
The utilisation of screen‐printing technology allows for a mass scalable approach for the production of electrochemical screen‐printed electrodes (SPEs) and the presence of a redox mediator can add ...new possibilities to the electrochemical properties of the SPEs. Among the materials used as redox mediators, cyanidoferrates polymers can be used for electro‐oxidation of cysteine. In this work, two monomers, namely, Fe(CN)64− and Fe(CN)5NH33− were used to produce Prussian blue (PB) and Prussian blue‐Ammine (PB‐Ammine), respectively. In addition, two modification methods were compared, firstly via a drop‐casting and secondly by the incorporation of these materials into a printable ink. The SPE modified by PB‐Ammine (drop‐casting) exhibits the highest electroactive area, however the highest heterogeneous rate constant was found with the SPE modified by PB‐Ammine that was incorporated into the ink. The highest value of the constant of electro‐oxidation of cysteine and lowest limit of detection was also observed in the SPE modified by PB incorporated into the ink. These studies suggest that the electrocatalytic properties of SPE modified by PB and PB‐Ammine are dependent upon the availability of Fe3+ catalytic sites and the increased kinetics of the chemical reaction between the catalytic sites and the analyte.
Hydrogen (H2) is presented as an important alternative for clean energy and raw material in the modern world. However, the environmental benefits are linked to its process of production. Herein, the ...chemical aspects, advantages/disadvantages, and challenges of the main processes of H2 production from petroleum to water are described. The fossil fuel (FF)‐based methods and the state‐of‐art strategies are outlined to produce hydrogen from water (electrolysis), wastewater, and seawater. In addition, a discussion based on a color code to classify the cleanliness of hydrogen production is introduced. By the end, a summary of the hydrogen value chain addresses topics related to the financial aspects and perspective for 2050: green hydrogen and zero‐emission carbon.
Hydrogen is an important alternative for clean energy and sustainable industrial processes. However, the environmental benefits are linked to its way of production. Herein, the environmental aspects represented by colors of H2 and challenges of H2 production from petroleum to water are described. Finally, a summary of the hydrogen value chain addresses topics related to perspectives by 2050.
In this paper, a low-cost and versatile lab-made photoreactor was constructed for the preparation of nanomaterials such as gold nanoparticles and reduced graphene oxide. The power of the lab-made ...photoreactor can be easily adjusted according to the number of lamps turned on. Moreover, the lab-made photoreactor allows the utilization of different sources of irradiation with distinct wavelengths. Performance tests for production of gold nanoparticles showed reproducibility and equal efficiency as compared to the literature. Also, the photoreactor powered with UV-A and UV-C as sources of irradiation can be used for modulation of the reduction degree of graphene oxide.
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•Akaganeites were synthesized with copper incorporated into the structure.•The characterization revealed the isomorphic substitution of iron by copper.•Presence of copper favored ...formation of hydroxyl radicals.•The doping improved the catalytic properties of the material.
In this work an iron oxide – akaganeite – was obtained and used as a Fenton catalyst for the oxidation of methylene blue. The ability of dye oxidation was evaluated after incorporating copper into the structure of akaganeite to improve the catalytic properties of the material. EDS spectroscopy shows the presence of copper in iron oxide whereas XRD, XANES and EXAFS reveal that copper is indeed incorporated into akaganeite’s structure. Color removal of methylene blue (MB) was monitored by UV–vis Spectroscopy. The results obtained by this technique showed that akaganeite doped with a higher percentage of copper presented better MB removal capacity, reaching 65.7% at 180min. The study by ESI–MS showed the formation of the intermediates during the degradation of this dye. Moreover, this material presented a significant mineralization of MB with removal of 45.5% of the organic carbon. The synergistic effect between iron and copper ions into the akaganeite structure favored formation of hydroxyl radicals, promoting the oxidation of the methylene blue dye.
Dye‐Sensitized Solar Cells
In article number 2100093 by Anish Babu Athanas and Swarnalatha KalaiyarHerein, a new coumarin‐based ruthenium(II) dye with tunable photophysical and redox properties is ...designed and synthesized. The dyesensitized TiO2 photoelectrodes are tested as photocurrent generators for both water‐splitting reactions and dye‐sensitized solar cells. The photoelectrochemical devices furnish a water‐splitting efficiency of 4.98% and power conversion efficiency of 4.16%.
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