Photocatalytic semiconductors require maintaining stability and pursuing higher efficiencies. The studied systems were silicon nanowires (Si_NWs), silicon nanowires with cobalt oxide nanoparticles (Si_NWs-CoO_NPs), and silicon nanowires with copper nanoparticles (Si_NWs-Cu_NPs). Si_NWs were synthesized by metal-assisted chemical etching (MACE) from silicon wafers keeping the remaining silver nanoparticles for all three sample types. The nanowires were about 23–30 µm in length. CoO_NPs and Cu_NPs were deposited on Si_NWs by the autocatalytic reduction processes (electroless). There were many factors in the process that affect the resulting structures and degradation efficiencies. This work shows the degradation of methyl orange (MO) together with the chemisorption of methylene blue (MB), and rhodamine 6G (Rh6G) by direct illumination with visible radiation. The MO degradation kinetics were in the sequence Si_NWs-Cu_NPs (88.9%) > Si_NWs (85.3%) > Si_NWs-CoO_NPs (49.3%), with the Si_NWs-Cu_NPs having slightly faster kinetics. However, Si_NWs-CoO_NPs have slow degradation kinetics. The chemisorptions of MB and Rh6G were Si_NWs-Cu_NPs (87.2%; 86.88%) > Si_NWs (86%; 87%) > Si_NWs-CoO_NPs (17.3%; 12%), showing dye desorptions together with lower chemisorption capacities. This work shows iridescence in optical microscopy images by the visible light interference caused by the spaces between the nanowire bundles.

The scope of this work covers a proposal for the implementation of sustainable, low-cost, environmentally friendly, and affordable housing for low-income people. This paper aims to address the current housing issues, namely that many people lack decent housing and that the built houses are usually of a poorly sustainable nature. The work consists of three main parts: an evaluation of housing sustainability, measurement of parameters related to their internal comfort and a simulation of thermal enclosure with the COMSOL Multiphysics^® software. An important objective is to propose a sustainability assessment format, which, besides being explained in detail, is presented in a percentage scale for ease of understanding. This work seeks a methodology for evaluating the level or degree of sustainability for the construction and inhabitation stages of housing. Using a prototype constructed with polyethylene terephthalate (PET) bottles, temperature and humidity were measured. There was a contrasting behavior of these two parameters, which tended towards an inverse behavior, except on cloudy or rainy days. The roof of the prototype contained some waste materials that provided thermal insulation: galvanized steel, polyethylene bags for upcycling as waterproofing, PET bottles, soil and endemic plants (green roof). The results obtained in the simulation are in accordance with the real internal behavior of the prototype.

Geopolymers have been mainly utilized as structural materials; their chemical structure and morphologies have been explored for their potential as a high-performance material in emerging applications. Geopolymer composites reinforced with materials based on agro-waste are attracting interest in engineering applications due to their easy processing, low cost, low density, and high strength-to-weight ratio. This investigation pursues an experimental methodology that consists of a scheme to make composites with a geopolymer matrix and agro-waste (rice husk, barley, and coffee) as aggregate material, that can be applied in various fields of construction. The study was intended to determine the influence of adding various agro-wastes on the mechanical properties of the geopolymer. According to the respective ASTM standards, the materials obtained were prepared and analyzed to determine their compressive strength, flexural strength, hardness and scanning electron microscopy (SEM)-determined characteristics. The results revealed that, for the compression tests, the composites formed by a sol-gel matrix and barley husk showed a better yield, obtaining the highest value of 3.5 N/mm². Concerning hardness testing, the composites with a geopolymer matrix and coffee husks obtained higher values compared to the other composites. For the flexural tests, the compounds with the sol-gel/fly ash matrix obtained the highest yield stress value, which was 5.25 MPa with an elastic modulus of 7.59 GPa. The results of the microstructural analysis showed good husk-matrix interaction, together with failure mechanisms. The conformation of such waste-based compounds may enable them to replace natural wood in some applications, such as in the finishing of interiors of homes, during the final stages in the construction of buildings, or in the decoration of inhabited houses, as well as in finishing in the manufacture of furniture.

This work shows a proposed room prototype and its thermal behavior evaluation. The room was built by using polyethylene terephthalate (PET) bottles filled with soil from the site for its walls and a roof made of multiple layers of reused materials. The construction had a green roof and skylights that were constructed out of upcycled entire glass bottles. Thermal measurements were made indoors and outdoors over the course of one year. Temperature and humidity sensors were used for internal measurements, and, at the same time, a reference sensor recorded data that corresponded to external environmental conditions. The constructed building differed by an average of 8.5 °C from the reference measurements of the external environment and an average of 24.24% in relative humidity. Thermograms were taken from the outside walls, which reached 54.2 °C, while internal wall temperatures reached 25.5 °C. Additionally, a thermal transfer simulation of the prototype was accomplished by using COMSOL Multiphysics. Simulation results approximated the experimental data. The prototype had low daily thermal fluctuations, which was considered a desirable thermal behavior. These results, along with the self-building practices, low costs, and reuse of waste materials, makes this kind of building a potentially feasible alternative.

This work aims to propose and describe bamboo metallizing, in part or totally, for furniture or aesthetical decorations. Bamboo provides a diverse metallic appearance; however, its use with real metal, already conferred to plastics, may increase the chance of use of this green material. The furniture industry requires sustainable options for both the base material for manufacturing of many pieces of furniture with a useful purpose, and surfaces finished with high quality and variety in their aesthetic appearance. This includes bamboo ornaments, which are useful to complement interior decoration. The coatings obtained include copper, silver, nickel, brass, and tin, each of which had some variants in luster. The main change incorporated into the process for metallizing nonconducting surfaces was the introduction of a common base for all surfaces, regardless of its roughness, shape, size, or other surface conditions. Then, this base was taken through an electroless process followed by electrolytic stages. Modification of the current process prevents the need for an initial stage of etching to increase chemical conditioning and roughness. The obtained metallic luster was that intended for decorative applications.