Nanoconfinement Effect Research Articles

Unveiling the Nanoconfinement Effect on Crystallization of Semicrystalline Polymers Using Coarse-Grained Molecular Dynamics Simulations.

Semicrystalline polymers under nanoconfinement show distinct structural and thermomechanical properties compared to their bulk counterparts. Despite extensive research on semicrystalline polymers under nanoconfinement, the nanoconfinement effect on the local crystallization process and the unique structural evolution of such polymers have not been fully understood. In this study, we unveil such effects by using coarse-grained molecular dynamics simulations to study the crystallization process of a model semicrystalline polymer-polyvinyl alcohol (PVA)-under different levels of nanoconfinement induced by nanoparticles that are represented implicitly. We quantify in detail the evolution of the degree of crystallinity (XC) of PVA and examine distinct crystalline regions from simulation results. The results show that nanoconfinement can promote the crystallization process, especially at the early stage, and the interfaces between nanoparticles and polymer can function as crystallite nucleation sites. In general, the final XC of PVA increases with the levels of nanoconfinement. Further, nanoconfined cases show region-dependent XC with higher and earlier increase of XC in regions closer to the interfaces. By tracking region-dependent XC evolution, our results indicate that nanoconfinement can lead to a heterogenous crystallization process with a second-stage crystallite nucleation in regions further away from the interfaces. In addition, our results show that even under very high cooling rates, the nanoconfinement still promotes the crystallization of PVA. This study provides important insights into the underlying mechanisms for the intricate interplay between nanoconfinement and the crystallization behaviors of semicrystalline polymer, with the potential to guide the design and characterization of semicrystalline polymer-based nanocomposites.

One-pot Synthesis of PdCuAg and CeO2 Nanowires Hybrid with Abundant Heterojunction Interface for Ethylene Glycol Electrooxidation.

Introducing CeO2 into Pd-based nanocatalysts for electrocatalytic reactions is a good way to solve the intermediate toxicity problem and improve the catalytic performance. Here we reported a simple strategy to synthesize the PdCuAg and CeO2 nanowires hybrid via a one-pot synthesis process under strong nanoconfined effect of specific surfactant as templates. Owing to the structural (ultrathin nanowires, abundant heterojunction/interfaces between metal and metal oxide) and compositional (Pd, Cu, Ag, CeO2) advantages, the hybrid showed significantly enhanced catalytic activity (6.06 A mgPd -1) and stability, accelerated reaction rate, and reduced activation energy toward electrocatalytic ethylene glycol oxidation reaction.

Understanding contributions of zeolite surface hydroxyl groups over Au/USY in selective oxidation of aromatic alcohols

Metal-zeolites catalysts are of great importance in selective organic conversions. Zeolites possess features of highly-ordered porous network, adjustable acidic properties (Brønsted/Lewis), spatial nanoconfinement effects, unique shape selectivity and the strong (hydrothermal-) stability. The role of zeolite hydroxyl (z-OH) groups, such as bridging ones in Si-O(H)-Al (B acids) and terminal ones in Al-OH and Si-OH (silanols), in catalysis is an interesting topic, particularly when they are not catalytic active sites, while they affect the catalytic performances. This study comprehensively investigated series of Au/USY catalysts in the selective oxidation of benzyl alcohol to benzaldehyde and clarified the dominating contributions of Al-associated z-OH groups to affecting catalytic conversions and selectivity via altering the Si/Al ratio and reducing z-OH groups by amorphous silica species derived from diethoxydimethylsilane under high-temperature calcination. The catalysts were characterized by XRD, BET, TEM, XPS, UV/Vis, FT-IR and in-situ DRIFT to investigate crystal structures, textural properties, morphologies, size distribution, chemical state of gold, acidity, and adsorptive properties. The experimental results proved that zeolites with a higher amount of z-OH groups tuned by Si/Al ratios or by diethoxydimethylsilane silylation exhibited higher catalytic activity because of the adsorption effect. Finally, a possible mechanism was discussed based on the experimental results and literature.

Insights into the thermomechanical and interfacial behaviors of polymer‐clay nanocomposites via coarse‐grained molecular dynamics simulations

AbstractPolymer‐clay nanocomposites (PCNs) are commonly applied as multi‐functional structural materials with exceptional thermomechanical properties, while maintaining the characteristics of lightweight and optical clarity. In this study, building upon previously developed coarse‐grained (CG) models for nanoclay and poly (methyl methacrylate) (PMMA), we employ molecular dynamics (MD) simulations to systematically investigate the thermomechanical properties of PCNs when arranged in stacked configurations. Incorporating stacked clay nanofillers into a polymer matrix, we systematically conduct shear and tensile simulations to investigate the influences of variations in weight percentage, system temperature, and nanoclay size on the thermomechanical properties of PCNs at a fundamental level. The weight percentage of nanoclay in nanocomposites proves to have a significant influence on both the shear and Young's modulus (e.g., the addition of 10 Wt% nanoclay leads to an increase of 32.6% in the Young's modulus), with each exhibiting greater mechanical strength in the in‐plane direction compared to the out‐of‐plane direction, and the disparity between these two directions further widens with an increase in the weight percentage of nanoclay. Furthermore, the increase in the size of nanoclay contributes to an overall modulus enhancement in the composite while the growth reaches a saturation point after a certain threshold of about 10 nm. Our simulation results indicate that the overall dynamics of PMMA are suppressed due to the strong interactions between nanoclay and PMMA, where the confinement effect on local segmental dynamics of PMMA decays from the nanoclay‐polymer interface to the polymer matrix. Our findings provide valuable molecular‐level insights into microstructural and dynamical features of PCNs under deformation, emphasizing the pivotal role of clay‐polymer interface in influencing the thermomechanical properties of the composite materials.Highlights CG modeling is performed to explore the thermomechanical behavior of PCN. Effects of nanoclay weight percentage and size on modulus are studied. Interface leads to nanoconfinement effect on Tg and molecular stiffness. Correlations between molecular stiffness and modulus are identified. Simulations show spatial variation of dynamical heterogeneity.

Single-molecule analysis of solvent-responsive mechanically interlocked ring polymers and the effects of nanoconfinement from coarse-grained simulations.

In this study, we simulate mechanically interlocked semiflexible ring polymers inspired by the minicircles of kinetoplast DNA (kDNA) networks. Using coarse-grained molecular dynamics simulations, we investigate the impact of molecular topological linkage and nanoconfinement on the conformational properties of two- and three-ring polymer systems in varying solvent qualities. Under good-quality solvents, for two-ring systems, a higher number of crossing points lead to a more internally constrained structure, reducing their mean radius of gyration. In contrast, three-ring systems, which all had the same crossing number, exhibited more similar sizes. In unfavorable solvents, structures collapse, forming compact configurations with increased contacts. The morphological diversity of structures primarily arises from topological linkage rather than the number of rings. In three-ring systems with different topological conformations, structural uniformity varies based on link types. Extreme confinement induces isotropic and extended conformations for catenated polymers, aligning with experimental results for kDNA networks and influencing the crossing number and overall shape. Finally, the flat-to-collapse transition in extreme confinement occurs earlier (at relatively better solvent conditions) compared to non-confined systems. This study offers valuable insights into the conformational behavior of mechanically interlocked ring polymers, highlighting challenges in extrapolating single-molecule analyses to larger networks such as kDNA.

N-doped carbon polyhedron-modified Co@N-doped carbon nanotube with enhanced [formula omitted] production for selective removal of organic pollutants

Persulfate-based advanced oxidation process dominated by singlet oxygen (1O2) shows potential for targeted degradation of organic pollutants but the regulation of 1O2 generation is still challenging. In this study, N-doped carbon polyhedron-modified Co@N-doped carbon nanotube (NCP/Co@NCNT) were successfully fabricated. The as-obtained NCP/Co@NCNT demonstrated a much enhanced 1O2 production in activating peroxymonosulfate (PMS) because of the nanoconfinement effect of metallic Co nanoparticles encapsulated in NCNT, which was further confirmed by density functional theory calculations. The NCP/Co@NCNT/PMS system has excellent catalytic performance and is capable of removing 97 % of carbamazepine (CBZ) in 55 min (Catalyst: 0.1 g/L, CBZ: 20 mg/L, PMS: 0.5 g/L). Quantitative structure–activity relationship (QSAR) analysis uncovered a positive correlation between the oxidation kinetics of organic pollutants and their EHOMO. Specifically, pollutants with higher EHOMO are more easily oxidized in the 1O2-dominated NCP/Co@NCNT/PMS system. Furthermore, the generated intermediates exhibited low toxicity in the system with 1O2 as the primary active species. This study offers an effective approach to prepare catalysts for the selective elimination of organic micropollutants in complex water environments.

Initial Occurrence State and Movability Evaluation of the Gulong Shale Oil Reservoir, Songliao Basin

The Qing-1 layer of the Gulong Depression in the northern Songliao Basin is a liquid-rich shale oil reservoir that has the characteristics of nanopores, high maturity, high gas/oil ratio (GOR), etc. The production performance of wells in the Gulong shale oil reservoir shows the characteristics of “single gas production followed by oil-gas production”. It is difficult to analyze the initial occurrence state and movability of fluid in the shale nanopores using conventional methods. In this study, a comprehensive method, including phase behavior analysis, physical experiments, and molecular simulation, was established to analyze the initial occurrence state and movability of fluid in the Gulong shale oil reservoir. The phase state of the fluid was calculated by the equation of state (EOS), considering nano-confinement effects, and the initial occurrence state was quantitatively evaluated by combining two-dimensional nuclear magnetic resonance (NMR) and molecular dynamics simulation. The movable fluid saturation was quantitatively determined by centrifugal experiments. The results show that the condensate gas state was in small pores, while the volatile oil state was in large pores. The occurrence states of oil were mainly adsorbed oil and free oil. The proportion of adsorbed oil in inorganic pores was about 24.4%, while the proportion of absorbed oil in organic pores was about 57.8%. Based on the cutoff value of T2 before and after the centrifuged laboratory experiments, the movable limit of oil was determined to be 4.5 nm, and the movable fluid saturation was about 11%. The research method proposed in this study has important guiding significance for the initial occurrence state and movability evaluation of similar liquid-rich shale reservoirs.

Constant charge method or constant potential method: Which is better for molecular modeling of electrical double layers?

In molecular modeling of electrical double layers (EDLs), the constant charge method (CCM) is prized for its computational efficiency but cannot maintain electrode equipotentiality like the more resource-intensive constant potential method (CPM), potentially leading to inaccuracies. In certain scenarios, CCM can yield results identical to CPM. However, there are no clear guidelines to determine when CCM is sufficient and when CPM is required. Here, we conduct a series of molecular simulations across various electrodes and electrolytes to present a comprehensive comparison between CCM and CPM under different charging modes. Results reveal that CCM approximates CPM effectively in capturing equilibrium EDL and current-driven dynamics in open electrode systems featuring ionic liquids or regular concentration aqueous electrolytes, while CPM is indispensable in scenarios involving organic and highly concentrated aqueous electrolytes, nanoconfinement effects, and voltage-driven dynamics. This work helps to select appropriate methods for modeling EDL systems, prioritizing accuracy while considering computational efficiency.

A Zn-Al-Zr layered double hydroxide/graphene oxide nanocomposite enables rapid photocatalytic removal of kanamycin-resistance bacteria and genes via nano-confinement effects

For efficient removal of the antibiotic-resistance bacteria and antibiotic-resistance genes, zirconium-doped zinc-aluminum layered double hydroxide/graphene oxide (Zn-Al-Zr LDHs/GO) nanocomposite has been developed. The Zn-Al-Zr LDHs/GO shows outstanding photocatalytic sterilization, inactivating kanamycin-resistance E. coli (6.53 log10 CFU/mL) under the full-wavelength light irradiation within 50 minutes. Owing to the 1O2 formation, it greatly disrupts the respiratory chain of the kanamycin-resistance E. coli, thereby leading to a declined yield of adenosine triphosphate, down-regulated expressions of the DNA ligase and polymerase proteins, as well as completely inhibited expressions of the DNA repair proteins. Meanwhile, the strong adsorption capability of the Zn-Al-Zr LDHs/GO towards phosphorus endows it with special nano-confinement effects for ARGs. It results in significantly enriched local concentration of the kanamycin-resistance genes on the Zn-Al-Zr LDHs/GO, consequently enhanced removal ability towards the kanamycin-resistance genes (4.70 log10 copies/mL in 3 hours). This work provides a new strategy for effectively removing the ARB and ARGs.

Tempospatially Confined Catalytic Membranes for Advanced Water Remediation.

The application of homogeneous catalysts in water remediation is limited by their excessive chemical and energy input, weak regenerability, and potential leaching. Heterogeneous catalytic membranes (CMs) offer a new approach to facilitate efficient, selective, and continuous pollutant degradation. Thus, integrating membranes and continuous filtration with heterogeneous advanced oxidation processes (AOPs) can promote thermodynamic and kinetic mass transfers in spatially confined intrapores and facilitate diffusion-reaction processes. Despite the remarkable advantages of heterogeneous CMs, their engineering application is practically restricted due to the fuzzy design criteria for specific applications. Herein, the recent advances in CMs for advanced water remediation are critically reviewed and the design flow for tempospatially confined CMs is proposed. Further, state-of-the-art CM materials and their catalytic mechanisms are reviewed, after which the tempospatial confinement mechanisms comprising the nanoconfinement effect, interface effect, and kinetic mass transfer are emphasized, thus clarifying their roles in the construction and performance optimization of CMs. Additionally, the fabrication methods for CMs based on their catalysts and pore sizes are summarized and an overview of their application and performance evaluations is presented. Finally, future directions for CMs in materials research and water treatment, are presented.

Confinement of CsPbBr3 Perovskite Nanocrystals into Extra-large-pore Zeolite for Efficient and Stable Photocatalytic Hydrogen Evolution.

Metal halide perovskites (MHPs), renowned for their outstanding optoelectronic properties, hold significant promise as photocatalysts for hydrogen evolution reaction (HER). However, the low stability and insufficient exposure of catalytically active sites of bulky MHPs seriously impair their catalytic efficiency. Herein, we utilized an extra-large-pore zeolite ZEO-1 (JZO) as a host to confine and stabilize the CsPbBr3 nanocrystals (3.4 nm) for boosting hydrogen iodide (HI) splitting. The as-prepared CsPbBr3@ZEO-1 featured sufficiently exposed active sites, superior stability in acidic media, along with intrinsic extra-large pores of ZEO-1 that were favorable for molecule/ion adsorption and diffusion. Most importantly, the unique nanoconfinement effect of ZEO-1 led to the narrowing of the band gap of CsPbBr3, allowing for more efficient light utilization. As a result, the photocatalytic HER rate of the as-prepared CsPbBr3@ZEO-1 photocatalyst was increased to 1734 μmol ⋅ h-1 ⋅ g-1 (CsPbBr3) under visible light irradiation compared with bulk CsPbBr3 (11 μmol ⋅ h-1 ⋅ g-1 (CsPbBr3)), and the long-term durability (36 h) can be achieved. Furthermore, Pt was incorporated with well-dispersed CsPbBr3 nanocrystals into ZEO-1, resulting in a significant enhancement in activity (4826 μmol ⋅ h-1 ⋅ g-1 (CsPbBr3)), surpassing most of the Pt-integrated perovskite-based photocatalysts. Density functional theory (DFT) calculations and charge-carrier dynamics investigation revealed that the dramatically boosted photocatalytic performance of Pt/CsPbBr3@ZEO-1 could be attributed to the promotion of charge separation and transfer, as well as to the substantially lowered energy barrier for HER. This work highlights the advantage of extra-large-pore zeolites as the nanoscale platform to accommodate multiple photoactive components, opening up promising prospects in the design and exploitation of novel zeolite-confined photocatalysts for energy harvesting and storage.

Confinement of CsPbBr3 Perovskite Nanocrystals into Extra‐large‐pore Zeolite for Efficient and Stable Photocatalytic Hydrogen Evolution

AbstractMetal halide perovskites (MHPs), renowned for their outstanding optoelectronic properties, hold significant promise as photocatalysts for hydrogen evolution reaction (HER). However, the low stability and insufficient exposure of catalytically active sites of bulky MHPs seriously impair their catalytic efficiency. Herein, we utilized an extra‐large‐pore zeolite ZEO‐1 (JZO) as a host to confine and stabilize the CsPbBr3 nanocrystals (3.4 nm) for boosting hydrogen iodide (HI) splitting. The as‐prepared CsPbBr3@ZEO‐1 featured sufficiently exposed active sites, superior stability in acidic media, along with intrinsic extra‐large pores of ZEO‐1 that were favorable for molecule/ion adsorption and diffusion. Most importantly, the unique nanoconfinement effect of ZEO‐1 led to the narrowing of the band gap of CsPbBr3, allowing for more efficient light utilization. As a result, the photocatalytic HER rate of the as‐prepared CsPbBr3@ZEO‐1 photocatalyst was increased to 1734 μmol ⋅ h−1 ⋅ g−1(CsPbBr3) under visible light irradiation compared with bulk CsPbBr3 (11 μmol ⋅ h−1 ⋅ g−1(CsPbBr3)), and the long‐term durability (36 h) can be achieved. Furthermore, Pt was incorporated with well‐dispersed CsPbBr3 nanocrystals into ZEO‐1, resulting in a significant enhancement in activity (4826 μmol ⋅ h−1 ⋅ g−1(CsPbBr3)), surpassing most of the Pt‐integrated perovskite‐based photocatalysts. Density functional theory (DFT) calculations and charge‐carrier dynamics investigation revealed that the dramatically boosted photocatalytic performance of Pt/CsPbBr3@ZEO‐1 could be attributed to the promotion of charge separation and transfer, as well as to the substantially lowered energy barrier for HER. This work highlights the advantage of extra‐large‐pore zeolites as the nanoscale platform to accommodate multiple photoactive components, opening up promising prospects in the design and exploitation of novel zeolite‐confined photocatalysts for energy harvesting and storage.

Multi-phase behavior and pore-scale flow in medium-high maturity continental shale reservoirs with Oil, CO2, and water

The application of CO2 to enhancing the recovery of continental shale oil has attracted considerable attention. However, the introduction of CO2 leads to intricate phase behavior and flow mechanisms. In this study, firstly, a three-phase equilibrium model is developed, with nano-confinement effects taken into consideration, to analyze the phase behavior of continental shale oil-CO2-water systems in both a bulk phase and nanopores. Building upon this, an improved pore network model is introduced to simulate steady-state oil–water flow while considering the alterations in fluid properties resulting from CO2 dissolution. The findings reveal that with the increase of CO2 injection, a transition from two phases of liquid and water to two phases of vapor and water, three phases of liquid, vapor and water, two phases of vapor and water, and ultimately a pure vapor phase occurs. The dissolution of CO2 exerts a pronounced impact on the composition and properties of the oil phase, and the viscosity and interfacial tension reduction effects play a central role in affecting the flow capacity. Nano-confinement effects facilitate the transfer of vapor-phase molecules into the water and oil phases, thus increasing the concentration of CO2 in the oil and water phases. The pore-scale flow results reveal that upon injection, water quickly traverses the larger pores. More smaller pores become accessible after CO2 dissolution, significantly boosting the extraction of shale oil from these smaller pores and slightly reducing the water output.

Influence of the confinement effect by a sandwiched subnanoreactor on the electrocatalytic performance for the nitrogen reduction reaction

Nanoconfinement effect allows precise tuning of catalyst performance by providing a spatially confined (sub)nanoscale environment for reaction systems. For the confined catalysts constructed from two-dimensional materials and transition metals, it can be achieved experimentally by wrapping metal nanoparticles in layers of carbon or other similar materials. Here, we propose a new type of confined catalyst composed of iron clusters sandwiched between graphitic carbon nitride and black phosphorus monolayers, and investigate its performance in the nitrogen reduction reaction by first-principles simulations. It is found that the overpotential at the Fe active site exhibits a significant decrease from 0.82 V to 0.49 V after the formation of the confined interfacial microenvironment, which is attributed to the spatial confinement by the two-dimensional monolayers and the change in binding patterns between the adsorbed species and the iron cluster. The corresponding selectivity in competition with the hydrogen evolution reaction is also improved to a certain extent. Moreover, the appearance of electronic states of the black phosphorus overlayer at the Fermi level further promotes the carrier transport in the electrochemical processes. Our work demonstrates the role of the nanoconfinement effect in enhancing the electrocatalytic performance and may shed new light on the rational design of electrocatalysts.

Highly efficient micropollutant decomposition by ultrathin amorphous cobalt-iron oxide nanosheets in peroxymonosulfate-mediated membrane-confined catalysis

Applications of advanced oxidation processes (AOPs) in water treatment require addressing technological challenges such as developing low-cost techniques for nanocatalyst synthesis, overcoming mass transfer limitations, and enhancing the yield of reactive oxygen species (ROS). This study employs a simple sodium borohydride (NaBH4)-based reduction technique for synthesizing ultrathin amorphous cobalt-iron oxide nanosheets (A/Co3-Fe ONS) to activate peroxymonosulfate (PMS). These nanosheets were found to outperform crystalline nanosheets due to their abundant reactive sites, oxygen vacancies, and capability to produce ROS through O–O and S–O bond cleavage. Due to the nanoconfinement effect, converting A/Co3-Fe ONS into a lamellar membrane significantly enhances reactivity and efficacy (1290 times) compared to batch PMS-mediated AOP reactors. Quenching experiments, solid-state and solution-based electron paramagnetic resonance (EPR) spectroscopy facilitated delineation of the reaction mechanisms involving both radical and nonradical pathways. Finally, the A/CoFeOx membrane achieved efficient removal (>95 %) of various organic micropollutants (OMPs), ultrafast destruction (318 ms), and excellent stability (48 h) through redox-recycling facilitated by the redox-potential difference and oxygen vacancies. This strategy offers a low-temperature cost-effective alternative and may be considered for scale-up in water treatment.

Core-shell nanoconfinement: Nanoreactors for directional electron migration in photothermal-assisted photocatalytic hydrogen production

Photothermal-assisted photocatalysis play crucial factors in solar to chemical/thermal energy conversion via the light–matter interaction. Herein, a photothermal nanoconfinement reactor comprised of a co-catalyst (Mo2C hollow spheres) as the core and a semiconductor photocatalyst (ZnIn2S4 nanosheets) as the shell was designed for achieving high-efficient photothermal-assisted photocatalytic H2 production. Remarkably, the optimal Mo2C@ZnIn2S4 core–shell nanoreactor attains an astonishing H2 evolution rate of 26.1 mmol g−1 h−1 under simulated sunlight irradiation and apparent quantum efficiencies (AQE, 420 nm) value of 19.4 %. The enhanced photocatalytic H2 production performance is attributed the unique core–shell structure can induce the directional migration of the photo-generated electrons excited by the shell (ZnIn2S4) to the nuclear region (Mo2C) with photothermal property, and effectively transport the electrons to the high-temperature zone through the nanoconfinement effect, thus ensuring the effective separation of the photogenerated carriers. This study provides an innovative design for high-efficient photothermal-assisted photocatalyst based on nanoconfinement effect.

A multi-mechanism numerical simulation model for CO2-EOR and storage in fractured shale oil reservoirs

Under the policy background and advocacy of carbon capture, utilization, and storage (CCUS), CO2-EOR has become a promising direction in the shale oil reservoir industry. The multi-scale pore structure distribution and fracture structure lead to complex multiphase flow, comprehensively considering multiple mechanisms is crucial for development and CO2 storage in fractured shale reservoirs. In this paper, a multi-mechanism coupled model is developed by MATLAB. Compared to the traditional Eclipse 300 and MATLAB Reservoir Simulation Toolbox (MRST), this model considers the impact of pore structure on fluid phase behavior by the modified Peng–Robinson equation of state (PR-EOS), and the effect simultaneously radiate to Maxwell–Stefan (M–S) diffusion, stress sensitivity, the nano-confinement (N-C) effect. Moreover, a modified embedded discrete fracture model (EDFM) is used to model the complex fractures, which optimizes connection types and half-transmissibility calculation approaches between non-neighboring connections (NNCs). The full implicit equation adopts the finite volume method (FVM) and Newton–Raphson iteration for discretization and solution. The model verification with the Eclipse 300 and MRST is satisfactory. The results show that the interaction between the mechanisms significantly affects the production performance and storage characteristics. The effect of molecular diffusion may be overestimated in oil-dominated (liquid-dominated) shale reservoirs. The well spacing and injection gas rate are the most crucial factors affecting the production by sensitivity analysis. Moreover, the potential gas invasion risk is mentioned. This model provides a reliable theoretical basis for CO2-EOR and sequestration in shale oil reservoirs.

Integration of galvanic reactions and engineered nanoconfinement in iron-copper nanocomposites for highly-efficient remediation of Cr(VI)-contaminated acidic/alkaline water

To eliminate trace toxic hexavalent chromium (Cr(VI)) from water with different pHs, researchers focused on adsorption, reduction of Cr(VI) to trivalent chromium with followed precipitation while the complex and costly reactivity regulations via adjusting pHs was inevitable. Here we exploit Fe-Cu nanocomposites (CnZVI/Cu) with galvanic reactions and engineered nanoconfinement effect for removing Cr(VI) from acidic/alkaline water directly, consisting of phosphorylated cracked nanoscale zero-valent iron (CnZVI, crack width of 1–2 nm) anode and Cu aggregates cathode. The formed primary battery exhibits strong electrostatic interactions towards ions and outstanding reactivity of reduction and precipitation at acidic/alkaline conditions. The pH inside the cracks at neutral or alkaline conditions is calculated to turn lower for enhancing the dynamics relevant to remediation. Benefiting from those two effects, the removal efficiencies of Cr(VI) through CnZVI/Cu attain more than 99.5 % at pH ≤ 8 and even 96 % at pH of 12 in only 30 min, outperforming the previous works. Its protection on beings (water spinach, zebrafish, and cell) from suffering poisonous Cr(VI), control of adsorbed Cr from migration, and magnetic collectability demonstrate the admirable removal performance, biosafety, and stability, respectively. This work proposes highly-efficient, eco-friendly, convenient, and low-cost technology to scavenge Cr(VI) from acidic/alkaline water.

Kinetics of nanoconfined benzyl methacrylate radical polymerization

AbstractThe effect of nanoconfinement on the kinetics of benzyl methacrylate radical polymerization is investigated using differential scanning calorimetry. Controlled pore glass (CPG), ordered mesoporous carbons, and mesoporous silica are used as confinement media with pore sizes from 2 to 8 nm. The initial polymerization rate in CPG and mesoporous silica increases relative to the bulk and increases linearly with reciprocal pore size; whereas, the rate in the carbon mesopores decreases linearly with reciprocal pore size; the changes are consistent with the rate being related to the ratio of the pore surface area to pore volume. Induction times are longer for nanoconfined polymerizations, and in the case of CPG and carbon mesopores, autoacceleration occurs earlier, presumably due to the limited diffusivity and lower termination rates for the confined polymer chains. The molecular weight of the polymer synthesized in the nanopores is generally higher than that obtained in the bulk except at the lowest temperatures investigated. The equilibrium conversion under nanoconfinement decreases with decreasing temperature and with confinement size, exhibiting what appears to be a floor temperature at low temperatures.

Nano-Confined Effect and Heterojunction Promoted Exciton Separation for Light-Boosted Osmotic Energy Conversion.

The osmotic energy conversion properties of biomimetic light-stimulated nanochannels have aroused great interest. However, the power output performance is limited by the low light-induced current and energy conversion efficiency. Here, nanochannel arrays with simultaneous modification of ZnO and di-tetrabutylammonium cis-bis(isothiocyanato)bis(2,20-bipyridyl-4,40-dicarboxylato) ruthenium (II) (N719) onto anodic aluminum oxide (AAO) to combine the nano-confined effect and heterojunction is designed, which demonstrate rectified ion transport behavior due to the asymmetric composition, structure and charge. High cation selectivity and ion flux contribute to the high power density of ≈7.33Wm-2 by mixing artificial seawater and river water. Under light irradiation, heterojunction promoted the production and separation of exciton, enhanced cation selectivity, and improved the utilization efficiency of osmotic energy, providing a remarkable power density of ≈18.49Wm-2 with an increase of 252% and total energy conversion efficiency of 30.43%. The work opens new insights into the biomimetic nanochannels for high-performance energy conversion.