Solar collectors represent an attractive green technology for water heating, where sunlight is efficiently absorbed by a selective coating and the generated heat is transferred to water. In this work, the improvement and scale-up of an electrodeposited black nickel selective coating with a modified silica (MS) film deposited by spray pyrolysis are reported. The MS material was prepared by the sol–gel method using tetraethyl orthosilicate with the addition of n-propyl triethoxysilane to obtain a porous film with an adequate refractive index and enhanced flexibility. The reflectance of electrodeposited selective coatings was characterized with and without the MS film and compared to a commercially available coating of black paint. The MS film increased the solar absorptance from 89% to 93% while maintaining a much lower thermal emittance than the painted coating. The reflectance of the MS film remained unchanged after prolonged thermal treatment at 200 °C (200 h). The fabrication process was scaled up to 193 cm × 12 cm copper fins, which were incorporated in commercial-size flat-plate solar collectors. Three complete collectors of an area of 1.7 m² were fabricated and their performance was evaluated under outdoor conditions. The results show that the electrodeposited selective coating with the MS film outperformed both the commercial black paint system and the system without the modified silica film.

Electrochemistry is a key technology to synthesize, study and scale-up materials and processes for applications in solar energy conversion systems. Mexico has had a tradition of excellence in electrochemistry research and methodology development, and this paper intends to honor some of the key contributors in the subjects of solar energy conversion to useful heat or electricity. We summarize the use of electrochemical techniques as a tool for the deposition and characterization, including the analysis of electrodeposition solutions and deposition mechanisms. In addition, we describe the use of electrodeposited and hybrid ZnO films for application in dye-sensitized solar cells, which are photoelectrochemical systems, and discuss the mechanisms that govern solar cell performance. Resumen. La electroquímica es una tecnología clave para sintetizar, estudiar y escalar materiales y procesos para aplicaciones en sistemas de conversión de energía solar. México ha tenido una tradición de excelencia en la investigación y el desarrollo de metodologías electroquímicas, y este documento tiene la intención de honrar a algunos de los principales contribuyentes en los temas de conversión de energía solar en calor o electricidad útil. Resumimos el uso de técnicas electroquímicas como herramienta para la deposición y caracterización, incluyendo el análisis de soluciones de electrodepósito y mecanismos de deposición. Además, se describe el uso de películas de ZnO híbridas y electrodepositadas para su aplicación en celdas solares sensibilizadas con tinte, que son sistemas fotoelectroquímicos, y discutimos los mecanismos que gobiernan el rendimiento de las celdas solares.

Spectral selective coatings are indispensable in solar thermal technologies for enhancing energy efficiency by maximizing solar absorption while suppressing thermal re-emission. This work presents a novel, cyanide-free electrodeposition method to develop high-performance selective coatings on aluminum substrates, using an alkaline copper-citrate bath as a sustainable and cost-effective adhesion layer. The copper plating process was evaluated across a pH range of 8.2 to 10.0 and characterized using speciation diagrams, UV-Vis spectrophotometry, cyclic voltammetry, and rotating-disk electrode (RDE) measurements with Koutecký–Levich analysis. Speciation diagrams and electrochemical data revealed that the [Cu2Cit2H-2]4- dimer is the dominant species in the pH 6–11 range. While this complex introduces a kinetic overpotential that suppresses deposition rates, it is fundamental for achieving the surface homogeneity and adhesion needed for subsequent layers. Building upon this optimized copper base, a nickel/black nickel selective coating was synthesized via controlled galvanostatic pulses. The coatings were characterized by reflectance spectroscopy, profilometry, SEM, XPS, FTIR, and XRD. Reflectance measurements prove that the selective coatings achieve a solar absorptance (α) of 94.3 % and a low thermal emittance (ε100) of 21.5 %, significantly outperforming commercial solar paint (α =89.2 % and e100 =59 %). Furthermore, photothermal heating curves confirmed that this electrochemical route yields superior photothermal conversion efficiency (ηST = 89.0 %) and remains thermally stable at 200 °C. This study offers a simplified, scalable, and environmentally friendly alternative for the large-scale implementation of high-efficiency solar thermal collectors.

The cement industry contributes approximately 7–8% of global CO₂ emissions, motivating the development of sustainable supplementary materials. This study evaluates the partial replacement (10 wt.%) of Portland cement with calcium carbonate (CaCO₃) derived from oyster shells, both untreated and thermally treated at 600 °C, in non-structural mortar blocks. Structural and physicochemical characterization was performed using XRD, SEM, EDS, BET, and TGA to assess phase composition, morphology, and surface properties. Thermal treatment modified the textural characteristics of CaCO₃, reducing the crystallite size and increasing the specific surface area (from 5.8 to 25.6 m²/g), without phase transformation. Compressive strength results, relative to a reference mortar (13.6 MPa), showed comparable performance, with variations generally within ±10%, although slightly larger deviations were observed for specific particle sizes. Finer calcined particles yielded the highest strength (15.0 MPa), reinforcing the combined influence of particle size and thermal treatment. These results suggest that CaCO₃ acts primarily through a filler effect, improving particle packing and matrix interaction. Both untreated and heat-treated CaCO₃ satisfied strength requirements for non-structural applications, supporting the valorization of oyster shell waste as a sustainable material in cement-based systems.