Challenges of Green Transition in Polymer Production: Applications in Zero Energy Innovations and Hydrogen Storage

The green transition in the sustainable production and processing of polymers poses multifaceted challenges that demand integral comprehensive solutions. Specific problems of presences of toxic trace elements are often missed and this prevents shifting towards eco-friendly alternatives. Therefore, substantial research and the development of novel approaches is needed to discover and implement innovative, sustainable production materials and methods. This paper is focused on the most vital problems of the green transition from the aspect of establishing universally accepted criteria for the characterization and classification of eco-friendly polymers, which is essential to ensuring transparency and trust among consumers. Additionally, the recycling infrastructure needs substantial improvement to manage the end-of-life stage of polymer products effectively. Moreover, the lack of standardized regulations and certifications for sustainable polymers adds to the complexity of this problem. In this paper we propose solutions from the aspect of standardization protocols for the characterization of polymers foreseen as materials that should be used in Zero Energy Innovations in Hydrogen Storage. The role model standards originate from eco-labeling procedures for materials that come into direct or prolonged contact with human skin, and that are monitored by different methods and testing procedures. In conclusion, the challenges of transitioning to green practices in polymer production and processing demands a concerted effort from experts in the field which need to emphasize the problems of the analysis of toxic ultra trace and trace impurities in samples that will be used in hydrogen storage, as trace impurities may cause terrific obstacles due to their decreasing the safety of materials. Overcoming these obstacles requires the development and application of current state-of-the-art methodologies for monitoring the quality of polymers during their recycling, processing, and using, as well as the development of other technological innovations, financial initiatives, and a collective commitment to fostering a sustainable and environmentally responsible future for the polymer industry and innovations in the field of zero energy applications.

Preparation of Anionic Surfactant-Based One-Dimensional Nanostructured Polyaniline Fibers for Hydrogen Storage Applications

Polyaniline fibers were prepared in the presence of anionic surfactant in an ice medium to nucleate in one dimension and were compared to bulk polyaniline prepared at an optimum temperature. Fourier-transform infrared spectroscopy (FTIR) and X-ray powder diffraction (XRD) were used to investigate the structural analysis of the prepared samples. A conductivity study reveals that polyaniline fibers have high conductivity compared to bulk polyaniline. Hydrogen storage measurements confirm that the polyaniline fibers adsorbed approximately 86% of the total actual capacity of 8–8.5 wt% in less than 9 min, and desorption occurs at a lower temperature, releasing approximately 1.5 wt% of the hydrogen gases when the pressure is reduced further to 1 bar.

A Bird's-Eye View on Polymer-Based Hydrogen Carriers for Mobile Applications

Globally, reducing CO2 emissions is an urgent priority. The hydrogen economy is a system that offers long-term solutions for a secure energy future and the CO2 crisis. From hydrogen production to consumption, storing systems are the foundation of a viable hydrogen economy. Each step has been the topic of intense research for decades; however, the development of a viable, safe, and efficient strategy for the storage of hydrogen remains the most challenging one. Storing hydrogen in polymer-based carriers can realize a more compact and much safer approach that does not require high pressure and cryogenic temperature, with the potential to reach the targets determined by the United States Department of Energy. This review highlights an outline of the major polymeric material groups that are capable of storing and releasing hydrogen reversibly. According to the hydrogen storage results, there is no optimal hydrogen storage system for all stationary and automotive applications so far. Additionally, a comparison is made between different polymeric carriers and relevant solid-state hydrogen carriers to better understand the amount of hydrogen that can be stored and released realistically.

Smart Synthesis of Hollow Microporous Organic Capsules with a Polyaniline Modified Shell

In this work, novel hypercrosslinked polymer-based hollow microporous organic capsules with a polyaniline (PANI)-modified shell (PANI@S-HMOCs) are prepared by in-situ polymerization of aniline in the porous structure of the sulfonated hollow microporous organic capsules (S-HMOCs). PANI@S-HMOC1, PANI@S-HMOC2, and PANI@S-HMOC3 are made by adjusting S-HMOCs and aniline weight ratios of 4:1 and 3:1, and 2:1, respectively. The characterizations of PANI@S-HMOCs demonstrate that electrostatic interaction between aniline and sulfonic acid groups plays an important role in encapsulating PANI in the pores of the shell. The content of PANI showed an evident effect on the porosity of PANI@S-HMOCs, and an appropriate polyaniline loading amount may increase the surface area. PANI@S-HMOC1 and PANI@S-HMOC2 have higher BET surface areas (529 and 503 m² g^-1 ) than S-HMOCs (424 m² g^-1 ), but PANI@S-HMOC3 has lower BET surface area (380 m² g^-1 ). Based on the structural and textural features, PANI@S-HMOC2 shows good adsorption performance for Cr(VI) from aqueous media (156 mg g^-1 , pH = 2, and 27 mg g^-1 , pH = 7).

Role of Adsorbed Polymers on Nanoparticle Dispersion in Drying Polymer Nanocomposite Films

Polymers adsorbed on nanoparticles (NPs) are important elements that determine the dispersion of NPs in polymer nanocomposite (PNC) films. While previous studies have shown that increasing the number of adsorbed polymers on NPs can improve their dispersion during the drying process, the exact mechanism remained unclear. In this study, we investigated the role of adsorbed polymers in determining the microstructure and dispersion of NPs during the drying process. Investigation of the structural development of NPs using the synchrotron vertical-small-angle X-ray scattering technique revealed that increasing polymer adsorption suppresses bonding between the NPs at later stages of drying, when they approach each other and come in contact. On the particle length scale, NPs with large amounts of adsorbed polymers form loose clusters, whereas those with smaller amounts of adsorbed polymers form dense clusters. On the cluster length scale, loose clusters of NPs with large amounts of adsorbed polymers build densely packed aggregates, while dense clusters of NPs with small amounts of adsorbed polymers become organized into loose aggregates. The potential for the quantitative control of NP dispersion in PNC films via modification of polymer adsorption was established in this study.

Recent Progress in Conducting Polymers for Hydrogen Storage and Fuel Cell Applications

Hydrogen is a clean fuel and an abundant renewable energy resource. In recent years, huge scientific attention has been invested to invent suitable materials for its safe storage. Conducting polymers has been extensively investigated as a potential hydrogen storage and fuel cell membrane due to the low cost, ease of synthesis and processability to achieve the desired morphological and microstructural architecture, ease of doping and composite formation, chemical stability and functional properties. The review presents the recent progress in the direction of material selection, modification to achieve appropriate morphology and adsorbent properties, chemical and thermal stabilities. Polyaniline is the most explored material for hydrogen storage. Polypyrrole and polythiophene has also been explored to some extent. Activated carbons derived from conducting polymers have shown the highest specific surface area and significant storage. This review also covers recent advances in the field of proton conducting solid polymer electrolyte membranes in fuel cells application. This review focuses on the basic structure, synthesis and working mechanisms of the polymer materials and critically discusses their relative merits.

Poly(3-aminobenzoic acid) Decorated with Cobalt Zeolitic Benzimidazolate Framework for Electrochemical Production of Clean Hydrogen

A novel composite of poly(3-aminobenzoic acid) (PABA) and a cobalt zeolitic benzimidazolate framework (CoZIF) has been studied for the production of hydrogen through the hydrogen evolution reaction (HER). The structural characteristics and successful synthesis of PABA, CoZIF and the PABA/CoZIF composite were confirmed and investigated using different techniques. Probing-ray diffraction for phase analysis revealed that the composite showed a decrease and shift in peak intensities, confirming the incorporation of CoZIF on the PABA backbone via in situ polymerization, with an improvement in the crystalline phase of the polymer. The thermal stability of PABA was enhanced upon composite formation. Both scanning electron microscopy and transmission electron microscopy showed that the composite had a rough surface, owing to an interaction between the CoZIF and the external surface of the PABA. The electrochemical hydrogen evolution reaction (HER) performance of the synthesized samples was evaluated using cyclic voltammetry and Tafel analysis. The composite possessed a Tafel slope value of 156 mV/dec and an α of 0.38, suggesting that the Volmer reaction coupled with either the Heyrovsky or Tafel reaction as the rate determining step. The fabricated composite showed high thermal stability and excellent tolerance as well as high electroactivity towards the HER, showing it to be a promising non-noble electrocatalyst to replace Pt-based catalysts for hydrogen generation.

Intense Pulsed Light-Treated Near-Field Electrospun Nanofiber on a Quartz Tuning Fork for Multimodal Gas Sensors

Accurate and portable gas sensors are required for environmental monitoring, locating leakages, and detecting trace chemical vapors or gases. Although many sensors have been developed, few can rapidly and selectively detect parts per million (ppm) concentration changes. In this work, we fabricate multimodal gas sensors by depositing a single nanocomposite fiber between the prongs of a quartz tuning fork (QTF). The resulting sensors are portable and integrate multimodal approaches by applying both chemo-mechanical sensing for sensitivity and electrochemical sensing for selectivity. Near-field electrospinning (NFES) produces a flexible and semiconductive nanocomposite fiber with ∼500 nm diameter that can be integrated into electronic systems as environmental gas sensors. Intense pulsed light (IPL) and sputter coating improve adhesion of the nanocomposite fiber onto a QTF. Furthermore, IPL offers improved sensing performance due to the higher specific surface area and reduction in polymer content. In this study, hydrogen gas (H₂) is chosen as a target gas since it is a common energy source in fuel cell applications and byproduct in chemical reactions. An electrospinning solution containing polyaniline, multiwalled carbon nanotubes, and platinum nanoparticles is used to test H₂ gas sensing performance. The resulting multimodal sensors are selective to hydrogen versus other gases and vapors including methane, hexane, toluene, ammonia, ethanol, carbon dioxide, and oxygen. Furthermore, the sensors detect ppm levels of hydrogen gas even in the presence of high humidity that typically hinders gas sensor performance. The development of this sensor leads to a new method for compact and portable multimodal gas sensing.