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3D printing technologies have been considered an important technology due to the ease manufacturing of objects, freedom of design, waste minimization, and fast prototyping. In chemistry, this technology potentializes the fabrication of conductive electrodes in large scale for sensing applications. Herein, we reported the modification of a 3D printed graphene electrode with Prussian blue. The modified electrode (3DGrE/PB) was characterized by microscopy (SEM and AFM) and spectroscopic techniques, and its electrochemical properties were compared to the traditional electrodes: glassy carbon, gold, and platinum. The 3DGrE/PB was used in the sensing of hydrogen peroxide in real-world samples of milk and mouthwash, and the results obtained according to the technique of batch-injection analysis were satisfactory for the concentration range typically found in such samples. Thus, 3DGrE/PB can be used as a new platform for sensing of molecular targets.

The search for earth-abundant metal-based catalysts for the oxygen evolution reaction (OER) that operates in neutral conditions is a challenge in the field of sustainable energy.

Raman spectroelectrochemistry is a powerful technique for characterizing structural changes of materials during electrochemical reactions and investigating the mechanism of film deposition and adsorption processes on the surfaces of electrodes. Moreover, in situ measurements enable identification of catalytic sites and reaction intermediates, which facilitates the comprehension of reaction mechanisms. The limitations of this technique include the high-cost and the complexity of the experimental arrangement required by commercial spectroelectrochemical cells (SEC). Thus, 3D-printing technology emerges as an excellent alternative for the production of SEC, with desirable shape, low-cost, and robustness in a short period of time. In this work, an SEC and a 3D-printed working electrode were fabricated from acrylonitrile−butadiene−styrene (ABS) and conductive graphene polylactic acid (PLA) filaments, respectively. The proposed SEC and the 3D-printed electrode were printed within 3.5 h with an estimated cost of materials of less than US $2. Then, the 3D-printed SEC and the electrode were used in a study of structural changes of Prussian blue according to different voltage bias.

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The design of an efficient, robust, and cost-competitive photoanode is often considered to be the bottleneck step to an industrial implementation of artificial photosynthesis. To overcome its drawbacks and to improve photoelectrochemical performance, water oxidation co-catalysts can be deposited on the photoanode. Coordination polymers based on Prussian blue, that is, cobalt cyanidoferrates, have emerged as promising water oxidation catalysts because of their low cost and tunable composition, while maintaining high efficiency and stability in a wide range of pH. They present an excellent alternative to typically used metal oxides, which show limited efficiency improvement. Indeed, the hexacyanidoferrate analog K x Co y [Fe(CN) 6 ]•nH 2 O appears to be an outstanding co-catalyst for decorating bismuth vanadate (BiVO 4 ) photoanodes, by enabling fast and irreversible hole transfer, combined with high catalytic efficiency. Because intrinsic catalytic activity can be modulated and enhanced by the introduction of pentacyanidoferrate precursors, we compared the effect of different pentacyanidoferrate derivatives on bismuth vanadate photoanodes for light-driven water oxidation. Our results indicate that the coordination polymers prepared using [Fe(CN) 5 (NH 3 )] 3− as a precursor lead to higher photocurrents and lower onset potential shifts. It is suggested that the relation between catalytic activity and ligand substitution is a combination of electronic effects imposed by the nature of the ligand and morphological effects, which regulate the number of active sites exposed and charge transport across the catalyst layer.