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We developed high performance PM6:N3 bulk-heterojunctions by synthesizing polymers as the second acceptor. The acceptor PY-P2 where a biphenyl linker makes the polymer chain to have high dihedral angles forms intricate alloy-like composites in N3 domains whereas stiff polymer chain of PY-T2 exists separated from the acceptor domain. Introduction of PY-P2 results in much longer lifetimes and diffusion lengths of excitons generated in N3 domain of the PM6:N3:PY-P2 blend compared to those of the excitons in PM6:N3 as well as PM6:N3:PY-T2. Consequently, the PM6:N3:PY-P2 based OPV devices show improved exciton dissociation and change transport with reduced charge recombination. The PM6:N3:PY-P2 organic photovoltaic (OPV) devices prepared with blade-coating at 1 cm2 active area achieved efficiency of 15.2% compared with 12.9% of the PM6:N3 control device; whereas, the corresponding OPV device using PY-T2 shows decreased efficiency of 11.7%. OPV mini-module (active area 5.4 cm2) with PY-P2 achieves high efficiency of 14.7% compared with 11.9% of the PM6:N3 devices. Furthermore, the alloyed PY-P2 acceptor effectively improves OPV thermal stability under 85 °C heating for 1000 h, compared with PY-T2 and control devices. We demonstrated importance of the second polymer acceptor for achieving high-performance large-area OPV, which is significantly affected by its chemical structure. We developed high performance PM6:N3 bulk-heterojunctions by introducing the second acceptor PY-P2. This results in longer lifetimes of excitons generated in N3 domain and improved exciton dissociation and change transport. PM6:N3:PY-P2 organic photovoltaic cells at 1 cm2 and the corresponding mini-module achieved high efficiency of 15.18% and 14.7%, respectively. PY-P2 effectively improves OPV thermal stability under 1000 h heating. [Display omitted] • Effect of the second polymeric acceptor, PY-P2, introduced in PM6:N3 blend. • Improved charge generation and transport by pseudo-charge transfer state in BHJ film. • High efficiency 1 cm2 OPV fabricated by a blade-coating. • High-performance OPV mini-module with 14.7% PCE. • Enhanced thermal stability with the addition of PY-P2 polymeric acceptor. [ABSTRACT FROM AUTHOR]

Automatically controlling the optical transmittance of solar light provides an energy-saving strategy for designing energy-efficient buildings. Ideally, the smart windows should be able to show homogeneous and large-scale color-switching performance while modulating the intensity of daylight. Among the suitable candidates for smart windows, the photochromic device has a great potential for homogenous and large-scale color-switching material. In a photochromic device, the intercalation/deintercalation of Li-ions is a key step determining the kinetics and efficiencies of the coloring/bleaching process. Herein, we exploit operando Raman spectroscopy to investigate the photochromic mechanism, which reveals the movement of Li ions into specific sites within the tunnels that exist in hexagonal tungsten oxide (WO 3). These spectroscopic results demonstrate that the intercalation/deintercalation of the Li ions is related to specific sites in the WO 3 lattice which stabilizes the energy of the intermediate state during the coloring/self-bleaching process. Additionally, theoretical simulation supports that electrons, as well as Li ions, participate in the color-switching performance. This study improves our understanding of the photochromic performance of this special device and opens up a research field toward the development of smart windows applications. [Display omitted] • A photochromic device is able to homogeneously change its color in large-scale entire device. • The oprando Raman spectroscopy can monitor coloring/bleaching processes in photochromic device. • The coloring/bleaching mechanism is related to tungsten oxide channels. [ABSTRACT FROM AUTHOR]

In alluvial aquifers with near-neutral pH and high dissolved arsenic (As) concentrations, the presence and character of sedimentary organic matter (SOM) regulates As mobility by serving as an energetically variable source of electrons for redox reactions or forming As–Fe-OM complexes. Near tidally and seasonally fluctuating rivers, the hyporheic zone (HZ), which embodies the mixing zone between oxic river water and anoxic shallow groundwater, may precipitate (or dissolve) iron (Fe)-oxides which sequester (or mobilize) As. To understand what is driving the mobilization of As within a shallow aquifer and riverbank sands adjacent to the tidally fluctuating Meghna River, we characterized the chemical reactivity of SOM from the sands, and a silt and clay layer, underlying the HZ and aquifer, respectively. Dissolved As (50–500 μg/L) and Fe (1–40 mg/L) concentrations increase with depth within the shallow aquifer. Similar vertical As and Fe concentration gradients were observed within the riverbank sands where concentrations of the products of reductive dissolution of Fe-oxides increase with proximity to the silt layer. Compared to all other sediments, the SOM in the clay aquitard contains older, more recalcitrant, terrestrially-derived material with high proportions of aromatic carboxylate functional groups. The shallow silt layer contains fresher SOM with higher proportions of amides and more labile polysaccharide moieties. The SOM in both the riverbank and aquifer is terrestrially-derived and humic-like. The labile SOM from the silt layer drives the microbially mediated reductive dissolution of As-bearing Fe-oxides in the HZ. In contrast, the carboxylate-rich SOM from the clay aquitard maintains dissolved As concentrations at the base of the aquifer by complexing with soluble As and Fe. This highlights that SOM-rich fine (silt or clay) layers in the Bengal basin drive As and Fe mobility, however, the specific processes mobilizing As and Fe depend on the lability of the SOM. [Display omitted] • Infrared spectroscopic analyses of sedimentary organic matter (SOM) from an arsenic contaminated river-aquifer interface. • Enrichment of polysaccharide and carbonyl functional groups in near-surface silt layer. • Enrichment of carboxyl function groups in underlying clay aquitard. • Labile SOM in the river-aquifer mixing zone promotes Fe and As mobility through reductive dissolution of Fe-oxides. • Recalcitrant SOM from clay aquitard promotes Fe and As mobility through complexation. [ABSTRACT FROM AUTHOR]

We have synthesized a series of benzo[1,2- b :4,5- b ′]-dithiophene (BDT)-co-thieno[3,4- b ]thiophene (TT) based polymers with various alkyl side chains and bridging-atom on their TT units and studied the effects of the variation in the effective van der Waals volumes (eVol) of the side chains on the photovoltaic properties of the associated bulk heterojunction (BHJ) solar cells. eVol was found to be correlated with the degree of phase separation in the BHJ film, which affects the area of the polymer-PC 71 BM interface and the charge mobility. The polymer has a 2-ethylhexyl group that results in a relatively optimal BHJ film morphology, with sufficient polymer-PC 71 BM interfacial area for efficient charge generation and minimal charge mobility loss upon BHJ film formation. As a result, the solar cell device (2-ethylhexyl polymer) exhibits the highest power conversion efficiency of 8.25% because its short-circuit current density value (16.24 mA/cm 2 ) and fill factor (0.674) are the highest of the synthesized polymers. [ABSTRACT FROM AUTHOR]

This study investigates the novel use of propionitrile (PN) as the single organic solvent for high-voltage carbon/carbon capacitors. Quaternary ammonium salts spiro-(1,1ʹ)-bipyrrolidinium tetrafluoroborate (SBPBF 4) and 1,1-dimethylpyrrolidinium tetrafluoroborate (DMPBF 4) dissolved in acetonitrile (AN) and propionitrile (PN) are compared. PN-based electrolytes exhibit a large and symmetric electrochemical stability, an exceptional anodic potential limit, good ionic conductivity, and low viscosity, allowing EDLCs to operate at 3.5 V even with a high current density (2.5 A g−1). Moreover, PN-based electrolytes can suppress the anodic dissolution of the Al current collector at a high potential. These advantages help in the realization of EDLCs with excellent cycling stabilities at high voltages. As a result, at 3.5 V, EDLCs with PN-based electrolytes exhibit the highest energy and power density of 49.3 Wh kg−1 and 22.9 kW kg−1, respectively. Therefore, the electrolyte systems reported here could be a promising electrolyte candidate to replace currently commercialized electrolytes for practical applications. Image 1 • SBPBF 4 and DMPBF 4 in AN and PN were used as electrolytes and compared. • PN-based electrolytes exhibited higher oxidation potentials. • EDLCs based on PN electrolytes exhibited the highest cycle life at 3.5 V. [ABSTRACT FROM AUTHOR]

This study reports a systematic investigation of electrolytes based on new salts consisting of various cations and the bis(oxalate)borate (BOB) anion for use in electrical double layer capacitors. The quaternary ammonium salts—tetraethylammonium tetrafluoroborate (TEABF 4), spiro-(1,1ʹ)-bipyrrolidinium tetrafluoroborate (SBPBF 4), 1,1-dimethylpyrrolidinium tetrafluoroborate (DMPBF 4), tetraethylammonium bis(oxalato)borate (TEABOB), spiro-(1,1ʹ)-bipyrrolidinium bis(oxalato)borate (SBPBOB), and 1,1-dimethylpyrrolidinium bis(oxalato)borate (DMPBOB)—were successfully prepared in high purity and dissolved in acetonitrile (ACN) at a concentration of 1.0 M. The successful synthesis of the salts was confirmed by nuclear magnetic resonance, ultraviolet–visible, and Fourier-transform infrared spectroscopies. The physicochemical properties and electrochemical performance of the prepared electrolytes, namely, thermal stability, ionic conductivity, viscosity, electrochemical stability window, specific capacitance, and durability, were investigated. Compared to the BF 4 -containing electrolytes, the new electrolytes based on the BOB anion, particularly the DMPBOB salt, showed dramatically enhanced high-voltage performance at elevated temperature. Electrical double layer capacitors based on 1 M DMPBOB in ACN exhibited a capacitance retention of 55.9% and a coulombic efficiency of >99% after 2000 cycles at a working voltage of 4.0 V and 45 °C. Moreover, X-ray photoelectron spectroscopy suggested that a highly stable protective layer induced by the BOB-containing electrolyte was formed on the negative electrode of the capacitor, inhibiting acute electrolyte decomposition during the cycling test. • The salts TEABOB, SBPBOB and DMPBOB were synthesized in high purity. • BF 4 and BOB-based salts in acetonitrile were used as electrolytes and compared. • The BOB-based electrolytes formed a protective layer on the negative electrode. • DMPBOB in acetonitrile exhibited the highest cycling stability at 4.0 V. [ABSTRACT FROM AUTHOR]

Groundwater containing high concentrations of dissolved arsenic (As) and iron (Fe(II)) discharges to rivers across the Ganges-Brahmaputra-Meghna delta. Observed Fe(III)-oxyhydroxide (FeOOH)–As deposits lining the riverbanks of the Meghna River may have been created by bidirectional mixing in the hyporheic zone (HZ) from ocean tides. This process has been named the Natural Reactive Barrier (NRB). Sedimentary organic carbon (SOC) is deposited annually on floodplains. Floodwaters that infiltrate through this layer may chemically transform the groundwater prior to discharging through the HZ in ways that influence the capture and retention of As in the NRB. The goal of this study is to understand how the interaction of these two scales of river-groundwater mixing influence the fate of As trapped within an NRB. Monitoring wells were installed to 1–17 m depth, up to 100 m distance from the river's edge during the dry season on the East (Site 1) and West (Site 2) sides of the river. They were sampled during the dry season (January) under gaining river conditions. The physical properties and elemental composition of the sediment was described by hand observation and hand-held X-Ray Fluorescence (XRF), respectively. Mixing with river water was quantified using the sum of charge of major cations (TC). Site 1 has a sloping bank that is only partially inundated during the wet season. The aquifer is composed of homogeneous sand. Site 2 is flat and therefore fully inundated in the wet season. The aquifer is composed of sand with thin (1–20 cm thick) clay layers. Both sites generate the dissolved products of FeOOH-reduction coupled to organic carbon oxidation, and silicate weathering beneath the floodplain. These products are dissolved Fe, As, silica, bicarbonate, calcium and phosphate. This chemistry is conducive to the formation of crystalline iron oxide minerals such as goethite which may co-precipitate with As, trapping it long-term. [Display omitted] • Intertidal zones along freshwater rivers trap arsenic on iron oxide surfaces. • Seasonally inundated floodplains drive silicate weathering. • Silicate weathering products influence iron oxide retention of arsenic. • Transported from seasonally to tidally inundated zones, products become reactants. [ABSTRACT FROM AUTHOR]

New small molecular semiconductors with small band gap and low-lying highest occupied molecular orbital ( E HOMO ), namely TBDPPOT, TBDPPEH, and TBDPPEHT4 were synthesized by incorporating the B←N bridged thienylthiazole and diketopyrrolopyrrole (DPP) derivatives. TBDPPOT and TBDPPEH were prepared, respectively, using two different DPPs having 1-octyl and 2-ethylhexyl moiety as the solubilizing group. In addition, the band gap of the TBDPPEH is further reduced by introducing planar thienothiophene unit, which was used for the preparation of TBDPPEHT4. These synthesized SMs are blended with fullerene derivative to construct a photo-active layer for organic photovoltaics. Among OPVs utilizing those SMs, the TBDPPEH exhibits highest power conversion efficiency of 3.21% with an exceptionally high V OC of 0.92 V, which is ascribed to low-lying HOMO energy level of −5.62 eV. It is expected that the utilization of TBDPPEH as a photo-active layer for OPVs would enhance the oxidation stability of the OPVs. [ABSTRACT FROM AUTHOR]

Solid polymer electrolytes (SPEs) have emerged as promising candidates for lithium-ion batteries. However, their practical application has been hindered by the limited ionic conductivity (< 10−3 S/cm), attributed primarily to the slow segmental dynamics of the polymer in the solid state. To elucidate the Li+ ion transport mechanism in SPEs, dielectric relaxation spectroscopy (DRS) can be used to measure both ionic conductivity and segmental dynamics simultaneously, as well as their temperature dependences. Various approaches have been explored to improve ionic conductivity, including the use of polymers with low glass transition temperature, high salt solubility, and an increased fragility. Additionally, single-ion conducting polymer electrolytes, polymer-in-salt systems, polymer blends, and composite SPEs have shown potential for achieving higher ionic conductivity. A novel approach focused on decoupling ion transport from polymer segmental relaxation and creating ion channels, such as super-ionic glasses, is currently under investigation to improve ionic conductivity at room temperature. In this review, we highlight recent DRS investigations that have provided insights into the Li+ ion transfer mechanism and its correlation with the improvement in ionic conductivities. [ABSTRACT FROM AUTHOR]

• A non-flammable electrolyte with fluorine-free salt is designed for high-voltage LMBs. • LiNO 3 combined with additives can form good SEI/CEI layer at li anode/NMC622 cathode. • The use of LiNO 3 is found to inhibit corrosion of the al current collector. • Insights into the solvation structure are revealed by spectroscopy and computational. Lithium nitrate (LiNO 3) is the preferred additive for achieving high efficiencies with improved lithium deposition morphologies due to its ability to form stable solid electrolyte interface (SEI) layers. However, LiNO 3 is not employed as its pure salt owing to its low solubility in common organic solvents. Here, we propose a non-flammable electrolyte (NF-LiNO 3 /GBL) consisting of LiNO 3 in γ-butyrolactone (GBL), wherein functional additives such as pentafluoro(phenoxy)cyclotriphosphazene (FPPN) and vinylene carbonate (VC) are added as a flame retardant and the solid electrolyte interphase (SEI)/cathode electrolyte interphase (CEI)-forming additive, respectively. Due to the strong interactions between Li+ and NO 3 − in the GBL, contact ion pairs and aggregates are the dominant ionic species even at a concentration of 0.8 M. Experimental and computational investigations demonstrated that the combination of LiNO 3 , GBL, FPPN, and VC forms SEI/CEI layers that are rich in conductive inorganic species, which can ultimately enhance the interfacial stability at the anode/cathode. The Li||Cu cells based on NF-LiNO 3 /GBL electrolyte exhibited a high average Coulombic efficiency of 98.3%, and Li||LiNi 0.6 Co 0.2 Mn 0.2 O 2 (4.3 V) cell based on NF-LiNO 3 /GBL maintained excellent capacity retention of 90% after 200 cycles. This work provides a promising non-flammable electrolyte for the production of safe and high-energy-density rechargeable lithium metal batteries. [Display omitted] [ABSTRACT FROM AUTHOR]

Elevated dissolved arsenic (As) concentrations in the shallow aquifers of Bangladesh are primarily caused by microbially-mediated reduction of As-bearing iron (Fe) (oxy)hydroxides in organic matter (OM) rich, reducing environments. Along the Meghna River in Bangladesh, interactions between the river and groundwater within the hyporheic zone cause fluctuating redox conditions responsible for the formation of a Fe-rich natural reactive barrier (NRB) capable of sequestering As. To understand the NRB's impact on As mobility, the geochemistry of riverbank sediment (<3 m depth) and the underlying aquifer sediment (up to 37 m depth) was analyzed. A 24-hr sediment-water extraction experiment was performed to simulate interactions of these sediments with oxic river water. The sediment and the sediment-water extracts were analyzed for inorganic and organic chemical parameters. Results revealed no differences between the elemental composition of riverbank and aquifer sediments, which contained 40 ± 12 g/kg of Fe and 7 ± 2 mg/kg of As, respectively. Yet the amounts of inorganic and organic constituents extracted were substantially different between riverbank and aquifer sediments. The water extracted 6.4 ± 16.1 mg/kg of Fe and 0.03 ± 0.02 mg/kg of As from riverbank sediments, compared to 154.0 ± 98.1 mg/kg of Fe and 0.55 ± 0.40 mg/kg of As from aquifer sediments. The riverbank and aquifer sands contained similar amounts of sedimentary organic matter (SOM) (17,705.2 ± 5157.6 mg/kg). However, the water-extractable fraction of SOM varied substantially, i.e., 67.4 ± 72.3 mg/kg in riverbank sands, and 1330.3 ± 226.6 mg/kg in aquifer sands. Detailed characterization showed that the riverbank SOM was protein-like, fresh, low molecular weight, and labile, whereas SOM in aquifer sands was humic-like, older, high molecular weight, and recalcitrant. During the dry season, oxic conditions in the riverbank may promote aerobic metabolisms, limiting As mobility within the NRB. [Display omitted] • Sediment from an As-contaminated aquifer and riverbank were geochemically studied. • Infiltrating oxic river water into riverbank hyporheic zone leads to solid-phase As enrichment. • Organic matter in aquifer sediments was highly humic-like and recalcitrant. • Organic matter in riverbank sediments was protein-like and biologically labile. • Fe and As are immobilized during the dry season when oxic river water moves laterally into the riverbank due to tides. [ABSTRACT FROM AUTHOR]

High-capacity Li 2 MnSiO 4 /C (LMS/C MBS) nanoparticles have been prepared using sonochemistry under a multibubble sonoluminescence (MBS) condition, and their physical and electrochemical properties were characterized. The results show that LMS/C MBS nanoparticles exhibit a nearly pure crystalline phase with orthorhombic structure and have a spherical shape and a uniform particle size distribution centered at a diameter of 22.5 nm. Galvanostatic charge–discharge measurements reveal that LMS/C MBS delivers an initial discharge capacity of about 260 mA h g −1 at a current rate of 16.5 mA g −1 in the voltage range of 1.5–4.8 V (vs. Li/Li + ), while LMS MBS (LMS without a carbon source under MBS) and LMS/C SG (LMS with a carbon source using the conventional sol–gel method) possess lower capacities of 168 and 9 mA h g −1 , respectively. The improved electrochemical performance of LMS/C MBS can be ascribed to the uniform nanoparticle size, mesoporous structure, and in-situ carbon coating, which can enhance the electronic conductivity as well as the lithium ion diffusion coefficient. [ABSTRACT FROM AUTHOR]

Abstract: In this article, we report the facile synthesis of metal-free dyes 6 and 7, their solution-based optical and redox properties and their use as sensitizers in dye-sensitized solar cells (DSSCs). Our studies indicate that the addition of the second thiophene unit in dye 7, decreases the oxidation and reduction potential and consequently the band gap of the molecule compared to 6. Furthermore, increasing the length of the conjugated spacer also affects on the properties of the DSSCs, with dye 7 providing a higher power conversion efficiency compared to 6 (η = 4.49 versus 3.23%). [Copyright &y& Elsevier]

Electrocatalytic systems affording stable performance beyond the initial catalytic activity and selectivity have been actively discussed. Understanding the long-term stability of nanoparticle catalysts requires careful monitoring of the morphological changes. Herein, we demonstrate the relationship between the degradation of the catalytic activity and morphological changes in Ag nanoparticles during the electrochemical CO 2 reduction reaction (CO 2 RR) for CO production by identical location transmission electron microscopy (IL-TEM) measurements. The synthesized Ag/C catalyst with 95.1% CO Faradaic efficiency (FE CO) at −0.82 V vs. RHE showed a gradual decrease in the CO production current density and FE CO , whereas the H 2 production increased during 12 h of CO 2 RR. IL-TEM images showed that small Ag particles with dimensions of less than 5 nm were newly formed from the original particles within 1 h of reaction, accounting for 80% of the total number of particles, and slowly grew to around 10 nm with multiple domains when the CO 2 RR was prolonged. These morphological changes were explained in connection with the CO current density gradient, where it was proposed that the formation of small particles causes a sharp decrease in the CO production during the first hour, and subsequent growth of the Ag nanoparticles did not restore the CO 2 RR activity of the particles. It was confirmed that degradation of the nanoparticles was more severe at a higher cathodic potential, and occurred during the CO 2 RR, but not in the hydrogen evolution reaction (HER) in N 2 -purged KHCO 3 electrolyte. In this study, we introduce analytical methods for observing morphological changes of nanoparticles in the identical location during CO 2 RR electrolysis. Image, graphical abstract [ABSTRACT FROM AUTHOR]