Dra. Elgueta-Herrera, Elizabeth

This study evaluated the stability and reusability of amino-functionalized nanocellulose aerogels as CO2-adsorbent materials. The modified aerogels, synthesized via a controlled silylation using N-[3-(trimethoxysilyl) propyl] ethylenediamine (DAMO), demonstrated excellent thermal stability up to 250 °C (TGA) and efficient CO2 adsorption through chemisorption, which was the main adsorption mechanism. The performance of the aerogels was assessed using both adsorption isotherms and the decay pressure technique, revealing that CO2 adsorption capacity increased with higher amino group loading (4.62, 9.24, and 13.87 mmol of DAMO). At 298 K and 4 bar, CO2 adsorption capacity increased proportionally with the amino group concentration, reaching values of 3.17, 5.98, and 7.86 mmol of CO2 g−1 polymer, respectively. Furthermore, over 20 adsorption/desorption cycles, the aerogels maintained 95% CO2 desorption at ambient temperature, indicating their potential for industrial use. These findings highlight the aerogels suitability as stable, reusable materials for large scale CO2 capture and storage technologies.

This review provides an overview of recent advancements in cathode materials for proton exchange membrane fuel cells (PEMFCs), focusing on their role in catalyzing the oxygen reduction reaction (ORR). This begins with a fundamental discussion of the ORR mechanism, including two‐electron and four‐electron pathways. The review then explores a wide range of electrocatalyst materials, starting with precious metal catalysts, particularly platinum‐based materials, along with alloying strategies and composite structures. This then delves into nonprecious metal catalysts, encompassing metal‐free ORR electrocatalysts, carbon‐supported composite materials (including heteroatom doping and metal‐carbon composites), and transition metal oxides. The review further examines metal phthalocyanines, biomass‐derived catalysts, bimetallic and trimetallic nanoparticles supported on carbon matrices, and chalcogenides (oxides, sulfides, and selenides) as ORR electrocatalysts. Advanced materials such as single‐ and dual‐atom catalysts, high‐entropy alloys, and metal organic frameworks derived electrocatalysts are also discussed. We analyze the identification of reaction sites and the effect of structure on catalytic activity. Furthermore, the review covers electrochemical measurements in PEMFCs and explores technological applications and industrial relevance, including products and patents. Finally, this review concludes by addressing future perspectives and challenges in the field of cathode materials for PEMFCs.

Bacterial nanocellulose (BNC) is a sustainable, renewable, and eco-friendly nanomaterial, which has gained great attentions in both academic and industrial fields. Two bacterial nanocellulose-producing strains (CVV and CVN) were isolated from apple vinegar sources, presenting high 16S rRNA gene sequence similarities (96%–98%) with Komagataeibacter species. The biofilm was characterized by scanning electron microscopy (SEM), revealing the presence of rod-shaped bacteria intricately embedded in the polymeric matrix composed of nanofibers of bacterial nanocellulose. FTIR spectrum and XRD pattern additionally confirmed the characteristic chemical structure associated with this material. The yields and productivities achieved during 10 days of fermentation were compared with Komagataeibacter xylinus ATCC 53524, resulting in low levels of BNC production. However, a remarkable increase in the BNC yield was achieved for CVV (690% increase) and CVN (750% increase) strains at day 6 of the fermentation upon adding 22 mM citrate buffer into the medium. This effect is mainly attributed to the buffering capacity of the modified Yakamana medium, which allowed to maintain pH close to 4.0 until day 6, though in combination with additional factors including stimulation of the gluconeogenesis pathway and citrate assimilation as a carbon source. In addition, the productivities determined for both isolated strains (0.850 and 0.917 g L−1 d−1) compare favorably to previous works, supporting current efforts to improve fermentation performance in static cultures and the feasibility of scaling-up BNC production in these systems.