In the last decades, the demand for electronics and, therefore, electronic waste, has increased. To reduce this electronic waste and the impact of this sector on the environment, it is necessary to develop biodegradable systems using naturally produced materials with low impact on the environment or systems that can degrade in a certain period. One way to manufacture these types of systems is by using printed electronics because the inks and the substrates used are sustainable. Printed electronics involve different methods of deposition, such as screen printing or inkjet printing. Depending on the method of deposition selected, the developed inks should have different properties, such as viscosity or solid content. To produce sustainable inks, it is necessary to ensure that most of the materials used in the formulation are biobased, biodegradable, or not considered critical raw materials. In this review, different inks for inkjet printing or screen printing that are considered sustainable, and the materials that can be used to formulate them, are collected. Printed electronics need inks with different functionalities, which can be mainly classified into three groups: conductive, dielectric, or piezoelectric inks. Materials need to be selected depending on the ink’s final purpose. For example, functional materials such as carbon or biobased silver should be used to secure the conductivity of an ink, a material with dielectric properties could be used to develop a dielectric ink, or materials that present piezoelectric properties could be mixed with different binders to develop a piezoelectric ink. A good combination of all the components selected must be achieved to ensure the proper features of each ink.

A super-hydrophobic surface at a high temperature (400 °C) using the sol-gel method with tetraethoxysilane (TEOS) and methyltriethoxysilane (MTES) as precursors has been obtained. The effects of the coatings’ ages, deposited times and thicknesses on the hydrophobicity of the silica coatings have been analysed. The morphology, chemical composition, thermal degradation and hydrophobicity of the resulting surfaces have been studied by scanning electron microscopy (SEM), Fourier transfer infrared spectrometer (FT-IR), Thermogravimetry (TGA) and water contact angle (WCA) measurement. The results show that an average water contact angle of 149° after been cured at 400 °C for a coating aged for 5 days, and four deposition cycles using a dipping rate of 1000 mm/min was achieved.

The need for clean and safe air quality is a global priority that extends to diverse environments, including households, industrial spaces, and areas requiring respiratory personal protection. In this study, polycarbonate (PC) nanofiber filters coated with a coating containing a silver salt were prepared by the electrospinning process and a subsequent dipping–extraction method. These nanofiber filters presented the enhancement of air filtration efficiency and reinforcement of antibacterial properties. The research includes diverse PC filter structures, assessing beaded and non-beaded structures and varying areal weights. The study evaluated filtration efficiency across NaCl particle sizes (50–400 nm) and pressure drop outcomes. In addition, the antibacterial activity of the coated filters against E. coli and other coliforms was investigated by the filtration membrane method. Repetitive testing consistently yields high efficiencies, reaching 100% in thicker filters, and minimal air resistance in beaded filters, presenting an advantage over the current systems. Furthermore, the new properties of the filters will enhance environmental safety, and their time of use will be increased since they prevented the growth of bacteria, and no significant colonies were seen. Considering all these factors, these filters presented promising application in environments with harmful microorganisms, for the development of advanced industrial filtering systems or even hygienic masks.

The transport sector is the fastest growing contributor to climate emissions and experiences the highest growth in energy use. This study explores the use of TiO₂ nanoparticles for obtaining photocatalytic nanocomposites with improved infrared reflectance properties. The nanocomposites were prepared by dispersing 0–20 wt% of TiO₂ nanoparticles in an unsaturated polyester resin. The effect of TiO₂ on the curing kinetics was studied by differential scanning calorimetry, showing a significant delay of the curing reactions. The thermal reflectance of the modified resins was characterized by UV-Vis-NIR spectrophotometry, measuring total solar reflectance (TSR). The TiO₂ greatly increased the TSR of the resin, due to the reflectance properties of the nanoparticles and the change in color of the modified resin. These nanocomposites reflect a significant part of near-infrared radiation, which can contribute to a reduction of the use of heating, ventilation, and air conditioning. Moreover, the photocatalytic effect of the TiO₂ modified nanocomposites was studied by monitoring the degradation of an organic model contaminant in an aqueous medium under UV light, and the reusability of the nanocomposites was studied with 5 cycles. The developed nanocomposites are proposed as a solution for reducing global warming and pollutant emissions.