Search Results (16)

Intermediate-temperature (IT) proton-exchange membranes (PEMs) play vital roles in hydrogen and direct liquid fuel cells, electrolyzers, and other electrochemical membrane reactors at elevated temperatures of higher than 150 °C. This article reports the fabrication and performance assessment of a type of new IT polymer–inorganic composite (PIC) PEMs that were made of cerium ultraphosphate (CeP₅O₁₄-CUP) as the durable solid-state proton conductor and undoped polybenzimidazole (PBI) as the high-temperature (HT) polymeric binder. The proton conductivity and electrochemical performance of the PIC PEMs were characterized at 200 °C with varying membrane thickness, processing parameters, and operating conditions using a single-stack hydrogen fuel cell connected to a fuel cell test station. Experimental results show that the PIC membranes (with CUP of 75 wt.%) carried high mechanical flexibility and strength as well as noticeably reduced water uptake of 4.4 wt.% compared to pristine PBI membranes of 14.0 wt.%. Single-stack hydrogen fuel cell tests at 200 °C in a humidified hydrogen and air environment showed that the proton conductivity of the PIC PEMs was measured up to 0.105 S/cm, and the electrochemical performance exhibited its dependence upon the membrane thickness with the power density of up to 191.7 mW/cm². Discussions are made to explore performance dependence and improvement strategies. The present study expects the promising future of the IT-PIC-PEMs for broad applications in high-efficiency electrochemical energy conversion and value-added chemical production at elevated temperatures of 200 °C or higher. Full article

Polybenzimidazole (PBI), a high-performance polymer known for its exceptional thermal stability and chemical resistance, was processed by solution electrospinning to manufacture fibrous non-woven membranes. The process was repeated under different conditions by adjusting four main settings: the polymer solution concentration, the flow rate, the voltage applied between the needle and the collector, and the separating distance. To clarify the interplay between process parameters and material properties, a Design of Experiment (DOE) approach was used to systematically analyze the effects of said parameters on microstructural properties, including fiber diameter, porosity, and air permeability, pointing out that the increase in viscosity improves fiber uniformity, while optimizing the applied voltage and the needle–collector distance enhances jet stability and solvent evaporation, crucial for defect-free fibrous microstructures. Post-processing via calendering further refined the membrane texture and properties, for example by reducing porosity and air permeability without significantly altering the fibrous morphology, particularly at low lamination ratios. Thermal and mechanical evaluations highlighted that the obtained electrospun PBI membranes exhibited enhanced flexibility, but lower tensile strength compared to cast films due to the underlying open pore microstructure. This integrated approach—combining experimental characterization, DOE-guided optimization, and post-processing via calendering—provides a systematic framework for tailoring PBI membranes for specific applications, such as filtration, fuel cells, and molecular sieving. The findings highlight the potential of PBI-based electrospun membranes as versatile materials, offering high thermal stability, chemical resistance, and tunable properties, thereby establishing a foundation for further innovation in advanced polymeric membrane design and applications for energy and sustainability. Full article

Organic–inorganic hybrid flexible perovskite solar cells (F-PSCs) have garnered considerable interest owing to their exceptional power conversion efficiency (PCE) and stable operational characteristics. However, F-PSCs continue to exhibit significantly lower PCE than their rigid counterparts. Herein, we employed 3-chloro-4-methoxybenzylamine hydrochloride (CMBACl) treatment to grow in situ two-dimensional (2D) perovskite layers on three-dimensional (3D) perovskite films. Through comprehensive physicochemical characterization, including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) mapping, we demonstrated that CMBACl treatment enabled the in situ growth of two-dimensional (2D) perovskite layers on three-dimensional (3D) perovskite films via chemical interactions between CMBA⁺ cations and undercoordinated Pb²⁺ sites. The organic cation (CMBA⁺) bound to uncoordinated Pb²⁺ ions and residual PbI₂, while the chlorine anion (Cl⁻) filled iodine vacancies in the perovskite lattice, thereby forming a high-quality 2D/3D heterojunction structure. The CMBACl treatment effectively passivated surface defects in the perovskite films, prolonged charge carrier lifetimes, and enhanced the operational stability of the photovoltaic devices. Additionally, the hybrid 2D/3D architecture also improved energy band matching, thereby boosting charge transfer performance. The optimized flexible devices demonstrated a PCE of 23.15%, while retaining over 82% of their initial efficiency after enduring 5000 bending cycles under a 5 mm curvature radius (R = 5 mm). The unpackaged devices retained 94% of their initial efficiency after 1000 h under ambient conditions with a relative humidity (RH) of 45 ± 5%. This strategy offers practical guidelines for selecting interface passivation materials to enhance the efficiency and stability of F-PSCs. Full article

Polybenzimidazoles (PBIs) are recognized for their remarkable thermal stability due to their unique molecular structure, which is characterized by aromaticity and rigidity. Despite their remarkable thermal attributes, their tensile properties limit their application. To improve the mechanical performance of PBIs, we made a vital modification to their molecular backbone to improve their structural flexibility. Non-π-conjugated components were introduced into PBIs by grafting meta-polyamide (MA) and para-polyamide (PA) onto PBI backbones to form the copolymers PBI-co-MA and PBI-co-PA. The results indicated that the cooperation between MA and PA significantly enhanced mechanical strain and overall toughness. Furthermore, the appropriate incorporation of aromatic polyamide components (20 mol% for MA and 15% for PA) improved thermal degradation temperatures by more than 30 °C. By investigating the copolymerization of PBIs with MA and PA, we unraveled the intricate relationships between composition, molecular structure, and material performance. These findings advance copolymer design strategies and deepen the understanding of polymer materials, offering tailored solutions that address thermal and mechanical demands across applications. Full article

This study aimed to determine the prevalence of the risk of orthorexia nervosa (ON) in dietetics students in Greece, and its relationship with diet, risk of eating disorder (ED), body mass index (BMI), body image flexibility, and parental attachment. The participants were 132 dietetics students, with a mean age of 22.94 ± 3.5 years, who completed a series of questionnaires that recorded sociodemographic, clinical, and anthropometric characteristics; adherence to the Mediterranean diet (MedDiet); ON indicators as determined by the ORTO-15 questionnaire; body image flexibility, with the Body Image-Acceptance and Action Questionnaire (BI-AAQ-5); the risk for ED as assessed using the EAT-26; anxiety level according to the STAIT 6 instrument; and recollection of their parents’ attitudes towards them during the first 16 years of life, with the Parental Bonding Instrument (PBI). ON risk appeared to be significantly associated with BMI (p = 0.002), exercise frequency (p = 0.023), anxiety level (p = 0.002), risk of ED (p < 0.001), body image inflexibility (p < 0.001), and inversely with the affectionate constraint of maternal bonding (p = 0.036). In conclusion, disordered eating behaviors and body shape concerns are prevalent among dietetics students, with parental attachment to the mother influencing their occurrence. Identification of potential ON and development of prevention mechanisms during childhood could help eliminate these concerns and improve the lives of dietetics students. Full article

Based on amino polybenzimidazoles with flexible hydrophilic side chains (AmPBI-MOE) and polymeric ionic liquid (PIL), a series of composite membranes (AmPBI-MOE-PIL-X) were fabricated for vanadium redox flow battery applications. Here, 1-Bromo-2-(2-methoxyethoxy)ethane was grafted onto amino polybenzimidazole (AmPBI) by the method of halogenated hydrocarbons, and PIL was synthesized from ionic liquids by in situ radical polymerization to build a hydrogen-bonded cross-linked network within the film. The hydrophilic side chain improves the proton conductivity. With the increase in ionic liquids, the vanadium transmittance and the proton conductivity increase. The AmPBI-MOE-PIL-5 membrane not only exhibits a vanadium ions permeability of 0.88 × 10⁻⁹ cm² min⁻¹, which is much lower than Nafion117 (6.07 × 10⁻⁸ cm² min⁻¹), but also shows a very excellent blocking ability for vanadium ion. The AmPBI-MOE-PIL-5 membrane shows excellent performances at 60 mA cm⁻², with VE of 87.93% and EE of 82.87%, both higher than that of Nafion117 membrane in VRFB. Full article

The aim of this study was to determine the prevalence of orthorexia nervosa (ON) among professional dancers in Greece, as well as its relationship with nutrition, body mass index (BMI), body image flexibility, and parental bonding. The participants were 96 professional dancers, with a mean age of 23.41 ± 5.13 years, who completed a battery of questionnaires recording sociodemographic, clinical, and anthropometric characteristics; adherence to the Mediterranean diet (MedDiet); indications of ON, as determined by the ORTHO-15 questionnaire; body image flexibility, using the body image-acceptance and action questionnaire (BI-AAQ-5); and their recollection of their parents’ attitudes towards them during the first 16 years of life, with the parental bonding instrument (PBI). The study population was classified into two groups, based on BMI: normal weight, and underweight. ON was shown to be significantly correlated with BMI (p = 0.006)-present in normal weight subjects- and body image inflexibility (p < 0.001). Parental body image inflexibility was significantly correlated with a low bonding relationship as perceived in childhood. In conclusion, disordered eating attitudes and body shape concerns are prevalent among professional dancers and appear to be associated with their parental relationship during childhood. Identification of potential ON and development of preventive mechanisms could help to eliminate such concerns and improve the nutrition of professional dancers. Full article

The unprecedented structural flexibility of hybrid halide perovskites is accompanied by a wide range of useful optoelectronic properties, causing a high interest in this family of materials. However, there are no systematic studies yet on the relationships between the topology of structures derived of chain 1D hybrid halide perovskites and their optoelectronic properties such as the band gap as already reported for 3D and 2D hybrid halide perovskites. In the present work, we introduce a rational classification of hybrid lead iodide 1D structures. We provide a theoretical assessment of the relationship between the topology of 1D hybrid halide perovskite-derived structures with vertex-connected octahedra and show that the distortions of geometry of the chains of PbI₆ octahedra are the main parameters affecting the band gap value while the distance between the chains of vertex-connected octahedra has a minor effect on the band gap. Full article

Organo-halide perovskite solar cells (PSCs) have emerged as next-generation photovoltaics, owing to their high power-conversion efficiency (PCE), lower production cost, and high flexibility. ABX₃-structured methylammonium lead triiodide (CH₃NH₃PbI₃ or MAPbI₃) perovskite is a widely studied light-absorbing material in PSCs. Interestingly, a small amount of chlorine incorporation into MAPbI₃ increases charge carrier diffusion lengths (from 129 nm to 1069 nm), which enables planar structured PSCs with high PCEs. However, existence of chloride ions in the final perovskite film is still under debate. Contrastingly, few studies reported a negligible amount or absence of chloride ions in the final film, while others reported detection of chloride ions in the final film. Herein, we observed the microstructure and chlorine content of MAPbI_3−xCl_x thin films with increasing temperature via an in-situ nano-Auger spectroscopy and in-situ scanning electron microscopic analysis. The relative precipitation of MAPbI_3−xCl_x films occur at lower temperature and MAPbI_3−xCl_x grains grow faster than those of MAPbI₃ grains. Local concentrations of chlorine at intragrain and the vicinity of grain boundary were analyzed to understand the behavior and role of the chloride ions during the microstructural evolution of the MAPbI_3−xCl_x films. Full article

Few-bit analog-to-digital converter (ADC) is regarded as a promising technique to greatly reduce power consumption of Internet of Things (IoT) devices in millimeter-wave (mmWave) communications. In this work, based on the recently proposed parametric bilinear generalized approximate message passing (PBiGAMP), we propose a new scheme to perform joint symbol detection, channel estimation and decoding. The proposed scheme is flexible to deal with discrete prior on symbols, Gaussian mixture prior on channels and quantized likelihood on observations. Furthermore, we introduce doping factor to control the portion of “extrinsic” and “posterior” information with negligible complexity increase. Since this joint scheme can be implemented via fast Fourier transformation (FFT), the complexity grows only logarithmically. Compared to the benchmark algorithms, numerical results show that the proposed joint scheme can achieve significant performance gain, and demonstrate the effectiveness in dealing with the nonlinear distortion from few-bit ADC. Full article

Methylammonium lead triiodide perovskite (CH₃NH₃PbI₃, MAPbI₃) has been emerging as an easy processing and benign defect material for optoelectronic devices. Fiber-like perovskite materials are especially in demand for flexible applications. Here we report on a kind of polyacrylonitrile (PAN)/MAPbI₃ composite fiber, which was electrospun from the mixing solution of PAN and MAPbI₃. The absorption edge and optical gap of the PAN/MAPbI₃ composite fibers can be easily tuned as the ratio of the perovskite changes. Both the moisture stability and the thermal stability of the perovskite are improved with the protection of PAN polymers. Flexible photodetectors based on this perovskite fiber were fabricated and analyzed. The photoresponse of the detector was highly sensitive to broadband visible light, and reached 6.5 μA W⁻¹ at 700 nm with a voltage bias of 10 V. Compared with pure MAPbI₃ photodetectors, this composite fiber photodetector has much-improved stability and flexibility, which can even be used to detect motion-related angular changes. Full article

Both exploitative and explorative innovations are needed for sustainable development in any industry, but balancing the two types is a delicate matter, and exploitation tends to be strongly prioritized in many industries. This is typically evident in project-based industries (PBIs), which are characterized by a fragmented supply chain and the delivery of one-off solutions in business projects. Realizing explorative innovations in this context is complex due to the need to transfer new knowledge between the organization developing the innovations and actors in inter-organizational business projects. The aim of this paper is to highlight areas in the management of explorative innovations developed outside business projects, to increase the understanding of where the specific market setting of PBIs might necessitate an adapted approach for successful realization. A case study of three innovation projects in organizations operating in PBIs have been conducted. The findings confirm that the major challenges lie in the transition between development project and business project. We highlight three aspects linked to this transition that require a flexible management approach: the assignation and acceptance of suitable responsibilities and roles, flexible support for the innovation process, and system acceptance. The findings may provide guidance for actors in PBIs strategically seeking to promote sustainable development, and provide foundations for further research to develop support for explorative innovation. Full article

In this work, efficient mixed organic cation and mixed halide (MA_0.7FA_0.3Pb(I_0.9Br_0.1)₃) perovskite solar cells are demonstrated by optimizing annealing conditions. AFM, XRD and PL measurements show that there is a better perovskite film quality for the annealing condition at 100 °C for 30 min. The corresponding device exhibits an optimized PCE of 16.76% with V_OC of 1.02 V, J_SC of 21.55 mA/cm² and FF of 76.27%. More importantly, the mixed lead halide perovskite MA_0.7FA_0.3Pb(I_0.9Br_0.1)₃ can significantly increase the thermal stability of perovskite film. After being heated at 80 °C for 24 h, the PCE of the MA_0.7FA_0.3Pb(I_0.9Br_0.1)₃ device still remains at 70.00% of its initial value, which is much better than the control MAPbI₃ device, where only 46.50% of its initial value could be preserved. We also successfully fabricated high-performance flexible mixed lead halide perovskite solar cells based on PEN substrates. Full article

Hybrid organic-inorganic perovskite has proved to be a superior material for photovoltaic solar cells. In this work we investigate the parameters influencing the growth of ZnO nanowires (NWs) for use as an efficient low temperature photoanode in perovskite-based solar cells. The structure of the solar cell is FTO (SnO₂:F)-glass (or PET-ITO (In₂O₃·(SnO₂) (ITO)) on, polyethylene terephthalate (PET)/ZnAc seed layer/ZnO NWs/CH₃NH₃PbI₃/Spiro-OMeTAD/Au. The influence of the growth rate and the diameter of the ZnO NWs on the photovoltaic performance were carefully studied. The ZnO NWs perovskite-based solar cell demonstrates impressive power conversion efficiency of 9.06% on a rigid substrate with current density over 21 mA/cm². In addition, we successfully fabricated flexible perovskite solar cells while maintaining all fabrication processes at low temperature, achieving power conversion efficiency of 6.4% with excellent stability for over 75 bending cycles. Full article

Using X-ray diffraction (XRD), it was confirmed that the deposition of hole-transporting materials (HTM) on a CH₃NH₃PbI₃ perovskite layer changed the CH₃NH₃PbI₃ perovskite crystal, which was due to the material exchanging phenomena between the CH₃NH₃PbI₃ perovskite and HTM layers. The solvent for HTM also changed the perovskite crystal. In order to suppress the crystal change, doping by chloride ion, bromide ion and 5-aminovaleric acid was attempted. However, the doping was unable to stabilize the perovskite crystal against HTM deposition. It can be concluded that the CH₃NH₃PbI₃ perovskite crystal is too soft and flexible to stabilize against HTM deposition. Full article