The growth trend of publications in the field of Proton Exchange Membrane Fuel Cell (PEMFC) was analyzed using bibliometric techniques to the identification of the areas with significant development and the orientations that have guided the research on energy cells. This study extracted the data from Scopus and Web of Science (WoS) databases to compare the bibliometric indicators of the published productions. In spite of bibliometric analysis advantages to knowing about the trends in a study area, this research requires methods to support the investigation process through the selection of a relevant bibliographic portfolio. This study applied the Methodi Ordinatio that provides a new approach to achieve it. A proposed list of the articles ranked by InOrdinatio is presented to compose the final portfolio. The obtained results in the research sub-theme of the Mass Transport in Gas Diffusion Layer (GDL) confirm the complexity in the study area by presenting erratic patterns of exponential growth. United States, China, and Japan are the leading countries on PEMFC publications. These countries have in common a strong spending by the business sector for R&D, and their gross domestic product is greater than 2%.

In this research, the effect of the addition of zirconium oxide-synthesized nanoparticles on the microstructural development and the physical–mechanical properties of cement mortars with limestone aggregates was studied. Zirconia nanoparticles were synthesized using the co-precipitation method. According to XRD analysis, a mixture of tetragonal (t) and monoclinic (m) zirconia phases was obtained, with average crystallite sizes around 15.18 and 17.79 nm, respectively. Based on the ASTM standards, a mixture design was obtained for a coating mortar with a final sand/cement ratio of 1:2.78 and a water/cement ratio of 0.58. Control mortars and mortars with ZrO₂ additions were analyzed for two stages of curing of the mortar—7 and 28 days. According to SEM analysis, mortars with ZrO₂ revealed a microstructure with a high compaction degree and an increase in compressive strength of 9% on the control mortars. Due to the aggregates’ characteristics, adherence with the cement paste in the interface zone was increased. It is suggested that the reinforcing effect of ZrO₂ on the mortars was caused by the effect of nucleation sites in the main phase C–S–H and the inhibition of the growth of large CH crystals, and the filler effect generated by the nanometric size of the particles. This produced a greater compaction volume, suggesting that faults are probably originated in the aggregates.

In this study, the photocatalytic activity of coating mortars with synthetized and commercial TiO₂ nanoparticles added has been evaluated at 2, 3 and 5% by weight of cement by calculating the degradation efficiency of methyl orange and red wine dyes exposed to both visible-light and UV radiation; also, the self-cleaning effect of coatings exposed to weather conditions (warm sub-humid climate) was assessed. TiO₂ nanoparticles were synthesized via the sol–gel method to a low synthesis temperature and characterized via X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). The results show synthesized TiO₂ particles in anatase phase with a crystallite size of 14.69 nm, and hemispherical particles with sizes of submicron order. The addition percentage with the best performance in the coating mortars was 3%, with both commercial and synthesized TiO₂; however, coating mortars with synthesized TiO₂ exhibited the highest degradation efficiency for both dyes when they were exposed to visible light, while mortars with commercial TiO₂ exhibited the highest degradation efficiency when exposed to UV radiation. In addition, in coating mortars with synthesized TiO₂, the self-cleaning effect was evident from the beginning of exposure to weather, reaching the largest dye-free surface at the end of exposure. The compressive strength increased significantly in mortars with TiO₂ addition.

Inorganic phase change materials (PCMs) can be employed in passive thermal regulation systems as building envelopes to decrease energy consumption. Nonetheless, they present a manifold of issues, such as leakage, incongruent melting, crystallization, and supercooling, which limit their performance and durability. A widely explored approach to address these shortcomings is the development of eutectic salts and their stabilization through techniques such as the use of porous substrates and encapsulation, in addition to combining them with the incorporation of carbon derivatives as fillers and nucleating agents to enhance thermal performance and durability during charge and discharge cycles. In this study, a critical review is developed via analysis and discussions of different methods for incorporating inorganic PCMs. The focus is mainly on eutectic salts and the challenges associated with their application, the generation of new eutectic salts, stabilization methods, and use cases where the incorporation of fillers, the use of porous substrates, and the implementation of nucleating agents have contributed to improving thermal performance, reducing the degree of supercooling, and minimizing PCM leakage during phase transitions.

For decades, researchers on materials science have highlighted the potential of biochar as a CO2 adsorption medium and the possibility of its incorporation into other materials to reduce the overall carbon footprint. This present study is a critical review of a selection of articles about biochar potential as a material on the construction industry. Biochar is a promising material in order to mitigate GHG emissions when added to cementitious materials, reducing its carbon footprint through a dual effect: CO2 sorption and replacement of cement or aggregates. Literature evidenced that replacement ratios of around 2-8 of cement wt% improved or leveled with conventional cementitious composites. However, some recent studies have shown that the incorporation of biochar up to >10% replacement ratios have the potential to improve the composites. Based on this premise, the present review emphasizes on the durability and long-term properties of biochar cementitious composites by providing up-to-date discussions of the studies on the matter and the future perspectives of the research in order to develop more eco-efficient concretes or mortars.