Controlled Functionalization Of Poly(4-Methyl-1-Pentene) Films For High Energy Storage Applications

A new family of poly(4-methyl-1-pentene) ionomer [PMP-(NH3)xA-y] (x = 1, 2, 3 and A = Cl-, SO42-, PO43-, y = NH3 content) modified (NH3+)xAx- ionic groups has been synthesized. The ionomers were synthesised using either a traditional Ziegler-Natta or a metallocene catalyst for the copolymerisation of 4-methyl-1-pentene and bis(trimethylsilyl)amino-1-hexene. A systematic study was conducted on the effect of the subsequent work-up procedures that can prevent undesirable side reactions during the synthesis of the [PMP-(NH3)xA-y] ionomers. The resulting PMP-based copolymers were carefully monitored by a combination of nuclear magnetic resonance (NMR), gel permeation chromatography (GPC), differential scanning calorimetry (DSC), mechanical properties, dielectric properties, and electric displacement-electric field (D-E) hysteresis loop measurements. Our results reveal that the [PMP-(NH3)xA-y] ionomer films show a significantly enhanced dielectric constant (∼5) and higher breakdown field (∼612 MV m-1) as compared with pure PMP films. Additionally, these PMP-based films show good frequency and temperature stabilities (up to 160 °C). A reliable energy storage capacity above 7 J cm-3 can be obtained, and is twice the energy storage capacity of state-of-the-art biaxially oriented polypropylene films, which can be attractive for technological applications for energy storage devices

Near-infrared responsive Z-scheme heterojunction with strong stability and ultra-high quantum efficiency constructed by lanthanide-doped glass

Lanthanide-doped near-infrared (NIR) photocatalyst still obstructed by the less impressive photocatalytic efficiency and stability. In this work, we report a novel strategy by introducing the lanthanide-doped ferroelectric perovskites of SiTiO3 and Sr2Bi4Ti4O15 into the glass-ceramic (GC), then an efficient and stable NIR photocatalyst was fabricated through the method of facile in-situ HCl etching GC. The results show that Sr2Bi4Ti4O15, SrTiO3, and BiOCl were exposed to the superficial coating of the core-shell structured photocatalyst and constructed Zscheme heterojunction, the heterojunction with built-in electric field could significantly facilitate the charge carriers separation and harvest NIR light for photocatalytic reaction simultaneously. The evident increase of Lewis basic sites over defect-rich photocatalyst is found, the center dot O2- and center dot OH radicals are generated. During the degradation of norfloxacin (NOR) under NIR light irradiation for 90 min, the NOR degradation rate is 86% (TOC removal rate is 30.7%), the high apparent quantum yield of 2.3% is achieved

Near-infrared responsive Z-scheme heterojunction with strong stability and ultra-high quantum efficiency constructed by lanthanide-doped glass

Lanthanide-doped near-infrared (NIR) photocatalyst still obstructed by the less impressive photocatalytic efficiency and stability. In this work, we report a novel strategy by introducing the lanthanide-doped ferroelectric perovskites of SiTiO3 and Sr2Bi4Ti4O15 into the glass-ceramic (GC), then an efficient and stable NIR photocatalyst was fabricated through the method of facile in-situ HCl etching GC. The results show that Sr2Bi4Ti4O15, SrTiO3, and BiOCl were exposed to the superficial coating of the core-shell structured photocatalyst and constructed Zscheme heterojunction, the heterojunction with built-in electric field could significantly facilitate the charge carriers separation and harvest NIR light for photocatalytic reaction simultaneously. The evident increase of Lewis basic sites over defect-rich photocatalyst is found, the center dot O2- and center dot OH radicals are generated. During the degradation of norfloxacin (NOR) under NIR light irradiation for 90 min, the NOR degradation rate is 86% (TOC removal rate is 30.7%), the high apparent quantum yield of 2.3% is achieved

Big disparities in CH4 emission patterns from landfills between the United States and China and their behind driving forces

Waste is the bridge linking resource consumption and greenhouse gas generation, and waste landfills are the main anthropogenic source of methane (CH4). The United States (US)–China Joint Glasgow Declaration and the Global Methane Pledge are committed to reducing tractable CH4 emissions; however, differences between the involved countries as well as their generation forecast processes have hampered cooperation. In this study, we provide a deep insight into CH4 emissions from municipal solid waste (MSW) landfills and identify the disparities in CH4 emissions with local socio-economic conditions. The US and China, the world's two largest economies, generated approximately 3.73 and 1.48 million tonnes of CH4 from 1248 to 1955 landfills in 2012 using the FOD/bottom-up method, with corresponding 26.93 and 11.94 kg per tonne waste and emission value from each landfill ranging between 100 and 105 and 10−5–105 tonnes. The spatial distribution was also quantified and compared with national, state/province, and urban agglomeration perspectives based on historical MSW variations (1990–2015) to clarify the triangular relationship between the economic situation, waste properties, and landfill CH4 emissions. High-density CH4 emission regions spatially overlapped with highly developed urban agglomerations, positively correlated with the local gross domestic product (GDP) and population (p 4 emissions from the waste sector. The increase in tertiary industry might reduce the waste sector's CH4 emissions. This study will help to understand this new triangular relationship and predict future patterns of CH4 emissions.</p

CaF₂‑Based Near-Infrared Photocatalyst Using the Multifunctional CaTiO₃ Precursors as the Calcium Source

Multistage formation of fluoride upconversion agents from the related-semiconductor precursors provides a promising route for the fabrication of near-infrared (NIR) photocatalysts with high photocatalytic activities. Herein, the cotton templated CaTiO₃ “semiconduction” precursors (C-CaTiO₃) were used to synthesize the NIR photocatalyst of Er³⁺/Tm³⁺/Yb³⁺–(CaTiO₃/CaF₂/TiO₂) (C-ETYCCT), and the functions of the Ca²⁺ source for CaF₂ and the heterostructure formations were displayed by C-CaTiO₃. The generated CaF₂ acted as the host material for the lanthanide ions, and the heterostructures were constructed among anatase, rutile, and the remaining CaTiO₃. The induced oxygen vacancies and Ti³⁺ ions enabled the samples to utilize most of the upconversion luminescence for photocatalysis. The NIR driven degradation rate of methyl orange (MO) over C-ETYCCT reached 52.34%, which was 1.6 and 2.5 times higher than those of Er³⁺/Tm³⁺/Yb³⁺–(CaTiO₃/TiO₂) (C-ETYCT) and Er³⁺/Tm³⁺/Yb³⁺–(CaTiO₃/CaF₂) (C-ETYCC), respectively. The degradation rates of MO and salicylic acid over C-ETYCCT with UV–vis–NIR light irradiation were also much higher than those of other samples, which were mainly results of the contributions of its high upconversion luminescence and the efficient electron–hole pair separation

Application of Ionized Intrinsic Microporous Poly(phenyl-alkane)s as Alkaline Ionomers for Anion Exchange Membrane Water Electrolyzers

Alkaline ionomers used in anion exchange membrane water electrolyzers (AEMWEs) require fast mass transport to maximize the activity of the catalytic reaction at the three-phase boundary. Taking advantage of the high free volume of polymers of intrinsic microporosity (PIMs), herein we propose a new strategy to apply ionized PIMs in the preparation of high-performance alkaline ionomers. A series of novel intrinsic microporous poly(phenyl-alkane) alkaline ionomers were synthesized by acid-catalyzed Friedel–Crafts polycondensation of electron-rich single-benzene/multi-benzene derivatives and trifluoromethyl/cyanide-substituted benzaldehydes. By adjusting the structure of aromatic monomers and aldehydes and the proportion of comonomers, the structures of the ionomer skeletons were systematically regulated. By evaluating the microporosities, ion transport properties, and device properties, we found that introducing a twisted spirobisindane unit and a trifluoromethyl substituent to the poly(phenyl-alkane) skeleton promoted the formation of more micropore structures. Increased microporosity is beneficial for the construction of efficient and stable mass transfer channels, facilitating improved AEMWE performance (1685 mA cm–2 at 1.8 V with a circulating 1 M NaOH solution at 80 °C) and excellent durability (>180 h at a high current density of 1000 mA cm–2). This work provides insights into the structure–property relationships of intrinsic microporous poly(phenyl-alkane) alkaline ionomers and demonstrates that ionic intrinsic microporous polymers are very promising candidates for the preparation of high-performance alkaline ionomers for AEMWEs

Morphology Evolution and Degradation of CsPbBr₃ Nanocrystals under Blue Light-Emitting Diode Illumination

Under illumination of light-emitting diode (LED) or sunlight, the green color of all-inorganic CsPbBr₃ perovskite nanocrystals (CPB-NCs) often quickly changes to yellow, followed by large photoluminescence (PL) loss. To figure out what is happening on CPB-NCs during the color change process, the morphology, structure, and PL evolutions are systematically investigated by varying the influence factors of illumination, moisture, oxygen, and temperature. We find that the yellow color is mainly originated from the large CPB crystals formed in the illumination process. With maximized isolation of oxygen for the sandwiched film or the uncovered film stored in nitrogen, the color change can be dramatically slowed down whether there is water vapor or not. Under dark condition, the PL emissions are not significantly influenced by the varied relative humidity (RH) levels and temperatures up to 60 °C. Under the precondition of oxygen or air, color change and PL loss become more obvious when increasing the illumination power or RH level, and the large-sized cubic CPB crystals are further evolved into the oval-shaped crystals. We confirm that oxygen is the crucial factor to drive the color change, which has the strong synergistic effect with the illumination and moisture for the degradation of the CPB film. Meanwhile, the surface decomposition and the increased charge trap states occurred in the formed large CPB crystals play important roles for the PL loss