Search Results (167)

Water-based perovskite solar cells (W-PSCs) provide a promising route toward reducing the use of hazardous organic solvents during perovskite fabrication. However, their development remains limited by sluggish precursor conversion, incomplete phase transformation, and poor control over film morphology. This review summarizes recent progress in W-PSCs, with particular emphasis on aqueous lead precursors and the subsequent conversion from precursor films to perovskite absorbers. The selection criteria for aqueous lead sources are first discussed in terms of water solubility, anion-Pb²⁺ interactions, precursor-solution stability, and ion-exchange behavior. Thermodynamic and kinetic considerations, including nucleation, crystal growth, reaction–diffusion coupling, and ion transport, are then discussed to provide a framework for understanding the conversion of aqueous precursor films into perovskites. Strategies for improving film formation are further classified into precursor-film and substrate engineering, conversion-process regulation, and ionic/compositional engineering. Particular attention is given to the role of precursor-film microstructure in regulating organic ammonium salt transport and conversion completeness. The photovoltaic performance of regular and inverted W-PSCs is subsequently compared, and the possible origins of their performance differences are discussed from the perspectives of precursor-film formation, perovskite conversion, film morphology, and interfacial properties. Finally, future opportunities in substrate-interface regulation, scalable aqueous processing, precursor and additive design, and life-cycle assessment are outlined. This review provides a reaction-diffusion-based perspective for understanding and improving water-based perovskite photovoltaics. Full article

Two-dimensional (2D) organic–inorganic hybrid perovskites exhibit coupled ionic, electronic, and electromechanical responses that can strongly influence local charge transport. Here, solution-processed mixed-halide butylammonium lead perovskite crystals were mechanically exfoliated and investigated using X-ray diffraction, atomic force microscopy, piezoresponse force microscopy (PFM), and conductive atomic force microscopy (c-AFM). PFM measurements under −5, 0, and +5 V revealed clear bias-dependent changes in amplitude and phase, indicating an electric field-sensitive local electromechanical response. Local c-AFM measurements showed nonlinear bipolar hysteresis, with a pronounced increase in current near +7–8 V and a decrease near −7 to −6 V during the subsequent negative sweep. Because the crystals are mixed ionic–electronic conductors and the nanoscale tip–sample junction introduces substantial injection and contact barriers, the observed behavior is interpreted as resistive switching-like conductivity modulation, rather than definitive ferroelectric switching. The results are consistent with the combined contributions of charge injection, trap filling, possible ionic redistribution, and piezoelectricity-associated modulation of the local transport barrier. These findings provide nanoscale insight into electric field-dependent electromechanical and out-of-plane conductive behaviors in layered 2D hybrid perovskites. Full article

Agricultural waste-derived biochars have recently attracted increasing attention as sustainable adsorbents for wastewater treatment. In this study, biochars (BHBs) produced from buckwheat husks at 500, 600, and 700 °C were investigated as novel adsorbents for the removal of the cationic dyes Crystal Violet (CV) and Rhodamine B (RhB) from aqueous solutions. The obtained materials were characterized using thermogravimetric analysis and surface functional group analysis to evaluate the influence of pyrolysis temperature on their physicochemical properties. The effects of initial adsorbent dose, solution pH, and ionic strength were assessed, while adsorption kinetics and equilibrium isotherms were analyzed to elucidate the adsorption mechanisms. It was found that the adsorption of both dyes depended on pH. CV adsorption was lowest in an acidic environment and increased with increasing pH from 3 to 9. RhB was most effectively adsorbed in an acidic environment. Its adsorption decreased as the pH increased from 3 to around 5, after which it stabilized. The adsorption of CV decreased with increasing ionic strength of the solution, whereas the adsorption efficiency of RhB remained unaffected. The adsorption kinetics of CV and RhB on BHBs were found to follow a pseudo-second-order mechanism controlled by film diffusion. The Langmuir, Freundlich, and Temkin models all provided good fits to the equilibrium experiments. The adsorption capacities of BHBs for CV and RhB decreased with increasing pyrolysis temperature and surface alkalinity of the biochars (BHB700 < BHB600 < BHB500). The adsorption capacities of biochars ranged from 41.00 mg/g (BHB700) to 56.10 mg/g (BHB500) for CV and from 9.74 mg/g (BHB700) to 13.24 mg/g (BHB500) for RhB. The study highlights the potential of buckwheat husk-derived biochars as sustainable adsorbents for the treatment of dye-contaminated wastewater and provides insight into the relationship between pyrolysis conditions and adsorption performance. Full article

The growing demand for flexible and environmentally friendly energy storage systems has increased interest in new electrolyte materials capable of operating at low temperatures. In this work, hydrogel polymer electrolytes based on aqueous choline lactate solutions were developed and evaluated for supercapacitor applications. Choline lactate was synthesized from biodegradable and low-toxicity substrates and characterized using spectroscopic and thermal analysis methods. A series of aqueous electrolytes with different salt concentrations was prepared, and their viscosity, density, and ionic conductivity were investigated to determine the optimal composition for hydrogel preparation. The obtained hydrogels were synthesized by photopolymerization and showed good flexibility, transparency, and structural stability without electrolyte leakage. Thermal analysis revealed that the presence of choline lactate effectively suppressed water crystallization, reducing the phase transition temperature of the hydrogel systems below −44 °C. Ionic conductivity increased with electrolyte content and reached 22.3 mS·cm⁻¹ at room temperature for the hydrogel containing 90 wt% electrolyte. Mechanical measurements showed that increasing electrolyte concentration improved flexibility but reduced stiffness and compressive strength. Electrochemical tests demonstrated stable supercapacitor operation in the temperature range from 25 °C to −20 °C, although lower temperatures led to decreased capacitance and increased internal resistance. The results indicate that choline lactate-based hydrogels are promising candidates for sustainable low-temperature energy storage devices. Full article

In protein solutions, an additive that increases protein–protein attractive interactions is expected to decrease protein crystal solubility and raise the temperature at which liquid–liquid phase separation (LLPS) occurs. In contrast, addition of 0.10 M 4-(2-hydroxyethyl)-1-piperazineethanesulfonate (HEPES) to lysozyme–NaCl aqueous solutions at constant pH (7.4) and ionic strength (0.20 M) decreases solubility but lowers the LLPS temperature. This leads to the broadening of the LLPS metastability gap in the phase diagram and an enhancement of protein crystallization yield from LLPS. We theoretically examine the effect of HEPES on both solubility and LLPS boundaries using a colloid model. Under the hypothesis that HEPES stabilizes protein–protein contacts in the crystal lattice by physical cross-linking, we apply cell theory to describe the thermodynamic behavior of the crystalline phase and use solubility data to show that HEPES increases protein–protein attraction energy by 2.7%. Since an increase in attraction incorrectly predicts a rise in the LLPS temperature, we consider that HEPES also enhances the anisotropic character of protein–protein interactions. To describe the thermodynamic behavior of the solution phase, we start from Barker–Henderson second-order perturbation theory on the hard-sphere reference fluid with square-well potential and local-compressibility approximation. We modify this model so that it can reproduce the correct mathematical expression of the second virial coefficient. This also leads to better agreement with Monte Carlo simulations. We then approximately incorporate anisotropy by assuming that the square-well attraction energy is a temperature-dependent average over all the surface of a particle with a given fractional coverage of attractive spots. The attraction energy of the attractive spots is set to be the same as that of the protein–protein contacts in the crystal. Only fractional coverage (anisotropy) was varied to successfully fit the effect of HEPES on the LLPS boundary. Full article

Vacancy-ordered double-perovskite Cs₂SnI₆ is known to be a good candidate for perovskite photovoltaics, as it is a light harvesting material which has potential both as an individual compound and as a component of a composite material. The compound is interesting due to being free of atom sites in B cationic positions, making the lattice “breathable” and giving it optoelectronic characteristics that vary with dopants. Here, antimony was examined as a possible heterovalent dopant with an ionic radius larger than that of Sn⁴⁺. In practice, it has been found that most of the materials are composites of Cs₂SnI₆ and Cs₃Sb₂I₉ phases. In the CsI–SnI₄–SbI₃ phase triangle, the melt crystallization process produced a layered (111)-oriented microstructure of crystallites with an increasing percentage of antimony. Two-dimensional perovskite materials look more promising in the decomposition of a solid solution to Cs₂SnI₆ and Cs₃Sb₂I₉ phases than in heterophase nucleation. The observed effect of (111)-oriented growth could be translated to other inorganic halides to form new oriented films or single crystals of perovskite materials. Diffuse reflectance spectroscopy showed an additional absorption shoulder in the NIR region for all groups of compounds, most likely induced by point defects in I sublattices of Cs₂SnI₆. Expanding the Cs₂SnI₆ absorption range to the NIR region could lead to new perspectives for its application. Full article

High-ash coal slime water, characterized by its stable colloidal suspension of fine kaolinite particles, poses a significant challenge in the coal preparation industry because it is hard to achieve efficient solid–liquid separation. While traditional coagulants and flocculants often suffer from limited bridging capabilities and distinct pH sensitivity, novel molecular architectures offer potential solutions. In this study, a star-shaped inorganic–organic hybrid flocculant (Al-PAM) was synthesized via in situ polymerization. Its flocculation performance and interfacial adsorption mechanism on the specifically targeted aluminol basal plane of kaolinite were systematically investigated and compared with Polyaluminum Chloride (PAC), Non-ionic Polyacrylamide (NPAM), and their combination (PAC + NPAM). Settling tests revealed that Al-PAM exhibited superior performance at a significantly lower dosage (10 mg∙L⁻¹) compared to the PAC + NPAM binary reagent system. It achieved a rapid initial settling velocity and reduced the supernatant turbidity to 48.45 NTU, while maintaining a near-neutral pH favorable for water recycling. Furthermore, Quartz Crystal Microbalance with Dissipation (QCM-D) monitoring confirmed that Al-PAM forms a thick, viscoelastic, and irreversible adsorption layer on the Al₂O₃ substrate. The dissipation shifts (ΔD) revealed that the star-shaped architecture promotes distinct bridging and electrostatic adsorption, overcoming the limitation of linear polymers. This work elucidates the specific contribution of the alumina-surface interaction with flocculants and proposes an efficient strategy for treating refractory coal slime water. Full article

Equimolar crystals of a high-entropy Ca_0.25Sr_0.25Ba_0.25Nd_0.25F_2.25 (CaSrBaNdF₉) fluoride solid solution were grown from a melt by the Bridgman technique, and their optical, electrical, and thermal properties were studied for the first time. This solid solution crystallizes in a fluorite-type structure (space group Fm-3m with lattice parameter a = 5.807 Å), is transparent over a wide spectral range, and has a refractive index of n_D = 1.5035(5). In terms of ionic conductivity (σ_dc increases monotonically from 3.7 × 10⁻⁵ to 3.9 × 10⁻⁴ S/cm in the studied temperature range of 643–810 K), it significantly exceeds the parameters of binary and ternary NdF₃-based single crystals, such as M_1−xNd_xF_2+x (M = Ca, Sr, Ba; x = 0.24–0.25) and Ca_0.58Sr_0.21Nd_0.21F_2.21. The grown multicomponent material is a hard (H_V~3.6 GPa) isomorphic-capacious crystalline matrix for various applications in solid-state ionics, optics and photonics, and opens up prospects for the development of new functional isotropic optical crystalline materials in quaternary CaF₂–SrF₂–BaF₂–RF₃ and higher-order complex fluoride systems nMF₂–mRF₃, where n + m ≥ 4, M and R are ions of alkaline earth and rare earth elements, respectively. Full article

The effects of Ca doping content on the crystal structure, electronic transport, thermal transport, and mechanical properties of In₂O₃ were systematically studied by means of X-ray diffraction (XRD), thermoelectric performance test, and first-principles calculation. XRD analysis shows that Ca²⁺ can be completely solid-dissolved into the In₂O₃ lattice to form a single-phase solid solution without the formation of impurity phases, and the lattice constant increases linearly with the increase in doping content, confirming that Ca²⁺ successfully replaces In³⁺ and triggers lattice expansion. The results of thermoelectric performance tests show that Ca doping can significantly improve the electrical conductivity of the material. The essence is that Ca doping introduces a large number of free electrons through the charge compensation effect, and coordinately regulates the carrier concentration and mobility to optimize the electronic transport performance. In terms of thermal transport performance, Ca doping leads to a decreasing trend of the total thermal conductivity of the material. The core mechanism is that the difference in ionic radius between Ca²⁺ and In³⁺ causes lattice distortion, enhanced mass fluctuation scattering, and defect scattering. At the same time, the decrease in Young’s modulus intensifies phonon scattering, resulting in a significant decrease in lattice thermal conductivity (dominating the change in total thermal conductivity), while the electronic thermal conductivity increases slightly but accounts for a very low proportion. Under the synergistic optimization of electrical and thermal transport, the thermoelectric figure of merit (ZT) of the material increases from ~0.05 to ~0.239, with particularly prominent effects in the medium and high-temperature range. Full article

Effective treatment of coal slime water is essential for sustainable coal preparation plant operation but hindered by the stable suspension of fine, negatively charged particles. To address this, a novel star-shaped inorganic–organic hybrid polymer (aluminum hydroxide-polyacrylamide, Al-PAM) was synthesized via in situ polymerization. Its performance was systematically compared with well-established coagulants/flocculants—polyaluminum chloride (PAC), non-ionic polyacrylamide (NPAM), and their binary combination through settling tests and quartz crystal microbalance with dissipation monitoring (QCM-D). The results showed a positive correlation between the molecular weight of Al-PAM and its flocculation efficiency. The optimal variant, Al-PAM-442, achieved an exceptionally high initial settling rate (50.4 m/h) and low supernatant turbidity (45.77 NTU) at an ultralow dosage of 6 mg/L. QCM-D analysis elucidated the mechanism: Al-PAM forms a thick, soft, and irreversibly adsorbed hydrated layer on silica, enabling strong electrostatic anchoring and effective polymer bridging. In contrast, PAC adsorption was reversible, while NPAM formed a thin, compact film with poor bridging capacity. Although the combined PAC/NPAM system showed synergistic performance, it required a significantly higher dosage (70 mg/L). This study demonstrates that the star-shaped Al-PAM architecture successfully integrates charge neutralization and bridging into a single molecule, offering a highly efficient and practical solution for industrial coal slurry dewatering. Full article

As oil and gas well development moves towards ultra deep formations, the high temperature at the bottom of the well causes the failure of copolymer retarders, leading to increased risk of oil and gas leakage and carbon emissions during cementing operations. To further ensure the safety of high-temperature oil and gas cementing operations, the influence of N,N-dimethylacrylamide (DMAA) on the high-temperature performance of copolymer retarders was explored. DMAA was introduced into copolymer retarders to form ultra-high temperature retarders. By analyzing the micro mechanism of copolymer retarders, the regulation of high-temperature retarders on the micro hydration process of cement slurry at high temperatures was revealed. Results showed that the cement slurry containing 3.0% SH5L (Pentameric copolymer retarder-introduced DMAA) exhibits a significantly similar thickening time with 3.4% SH4L (Quaternary copolymer-retarder) at 180 °C, demonstrating superior retardation performance at a lower dosage. The ultra-high-temperature polycarboxylate retarder SH5L was prepared by introducing the DMAA, enhancing its temperature resistance and retardation performance at high temperatures. The coupling of SH5L and Ca²⁺ retards the hydration and crystallization process of the cement slurry. The combination of rigid polycyclic structures and cationic monomers weakens the chelation between anionic groups and Ca²⁺, inhibiting the curling of polymers in ionic solutions. Polymer chains stretch with increasing temperature, enhancing their ability to bind with Ca²⁺ and improving their high-temperature retardation performance. Full article

Obtaining water-soluble palladium complexes capable of interacting with DNA is an important synthetic task in medicinal chemistry. The interaction of [Pd(phen)(OAc)₂] (phen = 1,10-phenanthroline) with pivalic acid (^tBuCOOH) and trifluoromethanesulfonic acid (HOTf) leads to the formation of the molecular complex [Pd(phen)(OOC^tBu)₂] (1) and the ionic complex [Pd(phen)(H₂O)₂]Otf₂ (2), respectively. Complex 1 is highly soluble in water and stable in solution for 48 h. When complex 2 is boiled in water, it undergoes hydrolysis to form the binuclear hydroxo-bridged complex [Pd₂(phen)₂(μ-OH)₂]Otf₂ (3). According to X-ray diffraction data, the crystal lattices of 1–3 are stabilized by numerous intermolecular hydrogen bonds and π-π stacking interactions. The interaction of 1 and 2 with DNA in vitro (in 0.005 M NaCl solution) was studied using UV spectroscopy, low-gradient viscometry, and DNA melting analysis. It was shown that both compounds interact with DNA, and the binding is accompanied by the intercalation of the phenanthroline ligand at low concentrations in the DNA solution. An increase in their concentration leads to an alternative binding mode—palladium–DNA interaction causes a decrease in the DNA molecular coil size due to electrostatic interaction and/or palladium coordination to DNA bases. The difference between the binding of compounds 1 and 2 to DNA is that 2 can coordinate to N-bases, unlike complex 1. The antibacterial properties of the complexes have been studied in vitro against E. coli, P. aeruginosa, and S. aureus. Full article

In coastal saline soil regions, foundation instability frequently arises due to salt heave, dissolution-induced weakening and corrosion-driven degradation. To enhance the engineering performance of fine-grained saline soil, this study evaluates the effectiveness of Enzyme-Induced Carbonate Precipitation (EICP) treatment under varying salinity levels and curing solution concentrations. Mechanical properties, hydraulic behavior and water stability were examined through unconfined compressive strength (UCS), disintegration and permeability tests, complemented by microstructural analyses using XRD and SEM. The results indicate that EICP notably improves mechanical strength, water stability and reduced permeability. The UCS of treated specimens increased by 37–152% relative to untreated soil, and disintegration time was prolonged by 214–563%. The permeability coefficient was reduced by 45.8–95.7%, demonstrating effective suppression of seepage channels. The optimal stabilization performance was achieved at 0.02% salinity and curing concentrations of 1.0–1.3×. Excessive salinity distorted vaterite crystal morphology and weakened cementation. XRD and SEM analyses revealed that vaterite dominated the calcium carbonate polymorphs, while ionic complexity influenced crystal structure, ACC conversion and pore-filling performance. These findings confirm the feasibility of applying EICP for improving fine-grained coastal saline soils and provide practical engineering guidance for coastal subgrades, reclamation foundations and port infrastructures. Full article

Dialdehyde crosslinked poly aspartate/alginate hydrogel beads were synthesized by covalently introducing poly aspartate into the alginate network via dialdehyde-mediated crosslinking, and the resulting effects on swelling and adsorption behavior were investigated. Alginate was partially oxidized to form dialdehyde alginate and crosslinked with poly aspartic acid via Schiff base formation, followed by ionic crosslinking with calcium ions. The chemical structure and morphology of the gel beads were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. Incorporation of PAsp significantly altered the swelling behavior of alginate-based gel beads. In saline solution, PAsp-modified gel beads exhibited a swelling ratio of approximately 112 g/g, which was higher than that of calcium alginate gel beads. This behavior is suggested to be associated with changes in the alginate–calcium network structure induced by polymer modification. PAsp-modified gel beads exhibited moderate but distinct adsorption behavior depending on the adsorbate. Removal efficiencies of approximately 40–50% were observed for copper and cobalt ions, while a removal efficiency of around 50% was obtained for the cationic dye crystal violet. In contrast, adsorption of the anionic dye Congo red decreased with increasing PAsp content, indicating charge-dependent adsorption behavior. Overall, this study demonstrates that PAsp modification via dialdehyde-mediated crosslinking influences both the swelling and adsorption properties of alginate-based hydrogel beads. The results provide fundamental insight into how network modification can be used to tune the behavior of alginate-based hydrogels in aqueous environments. Full article

Poly(vinylidene fluoride) (PVDF) nanofibers have emerged as promising materials for flexible piezoelectric sensors, yet their performance is fundamentally constrained by the limited formation and alignment of the electroactive β-phase. In this study, we report a phase-engineering strategy that integrates ionic functionalization, inorganic nanofiller incorporation, and post-fabrication corona poling to achieve enhanced crystalline ordering and electromechanical coupling in electrospun PVDF nanofibers. Tetrabutylammonium perchlorate increases solution conductivity, enabling uniform, bead-free fiber formation, while barium titanate nanoparticles act as nucleation centers that promote β-phase crystallization at the expense of the non-polar α-phase. Subsequent corona poling further aligns molecular dipoles and strengthens remnant polarization within both the PVDF matrix and embedded nanoparticles. Structural analyses confirm the synergistic evolution of crystalline phases, and piezoelectric measurements demonstrate a substantial increase in peak-to-peak output voltage under dynamic loading conditions. This combined phase-engineering approach provides a simple and scalable route to high-performance PVDF-based piezoelectric sensors and highlights the importance of coupling crystallization control with dipole alignment in designing next-generation wearable electromechanical materials. Full article