High Surface Energy Research Articles

3D porous conductive matrix based on phase-transited BSA and covalent coupling-stabilized transition ZnS-CNT for antifouling and on-site detection of nitrite in soil

Nitrite plays a critical role in a variety of nitrification and denitrification processes in the nitrogen cycle. Due to the high surface energy, tendency to aggregate, and poor conductivity, current nitrite ZnS-based sensing platform could not meet the need of on-site nitrite detection in smart agriculture. In order to address these issues, the carboxylated carbon nanotube (CNT) was introduced to reduce the surface energy and prevented aggregation of ZnS, while ZnS-carboxylated CNT (ZnS-CNT) composite also provided excellent electrochemical conductivity. Furthermore, the introduction of phase transition BSA (PTB) created a three-dimensional porous conductive matrix without interfering with the mass transfer process of nitrite. The resulting sensing platform exhibited a linear detection range of 10 nM to 0.4 mM for nitrite, with a detection limit of 0.73 nM. And this sensing platform had the excellent antifouling ability to direct detection nitrite in real soil suspension. In addition, the sensing platform demonstrated remarkable resistance to interferences from pH variations, microbial presence, and organic pollutants that usually present in soil environment. Therefore, on-site detection of nitrite ions in soil environment was realized no needing complex pretreatments.

Constructing adaptive silicon–carbon interconnected network for high-energy lithium-ion batteries

Nano-silicon (n-Si)/graphite anodes are highly desirable for high-energy lithium-ion batteries. Nevertheless, the high surface energy of n-Si grains is prone to causing serious agglomeration. In this work, the modified n-Si is evenly dispersed on the g-C3N4 carbon mesh that acquired through melamine heat treatment constructing an adaptive Si-carbon interconnection network structure (mSi50/g-C3N4). Ideally, the mSi50/g-C3N4 composite can be well dispersed and fill the gaps in graphite through traditional ball milling processes. The obtained mSi50/g-C3N4/Gr composite prevents the accumulation of Si grains which is beneficial for expediting ion transport, improving conductivity and structural stability. As a result, this anode provides a reversible capacity of 621 mAh⋅g−1 at 0.2 C, with high-capacity retention of 93.3 % after 300 cycles at 1 C and low volume expansion of only 28.6 %. Furthermore, it also maintains excellent cycling stability in full batteries with LiFePO4 cathode. Therefore, constructing the mSi50/g-C3N4 network is an effective strategy to achieve uniform dispersion of Si in graphite and promote larger scale industrialization of n-Si/graphite anode.

How cooling surface affect nucleation and impurity migration behavior during layer melt crystallization: A case study of 2′,4′-dichloro-5′-fluoroacetophenone

As a green and efficient purification technology, layer melt crystallization is widely used in chemical separation industry. However, during the melt crystallization process, how surface properties and cooling rate affect the metastable zone width (MSZW) and how MSZW affects the impurity migration in the cooling stage and sweating stage are rare explored. In this paper, 2′,4′-dichloro-5′-fluoroacetophenone is taken as a case study to explore this problem. Firstly, our results indicate that MSZW increases with increasing surface energy of the cooling surface. Importantly, we propose a new model to predict that ΔT/T0/T1 has a linear relationship with ln (R/T0/ΔT), which is validated by MSZW experiments. Secondly, the separation effect of the cooling surface with low surface energy is better than that of the surface with high surface energy. The purity of the crystal layer during sweating is limited by the cooling stage's separation effect. Finally, by employing mass balance, we predict that the impurity distribution coefficient of the crystal layer before and after sweating is linear, and this relationship is unaffected by the cooling surface and cooling rate, which is successfully verified by experiments.

In Situ Construction of a Lithiophilic and Electronically Insulating Multifunctional Hybrid Layer Based on the Principle of Hydrolysis for a Stable Garnet/Li Interface

AbstractAdapting solid‐state Li‐metal batteries is an attractive way to pursue higher energy density and safety compared to liquid‐based ones. With high ionic conductivity and excellent stability with Li, Ta‐doped Li7La3Zr2O12 (LLZTO) is an effective option. However, the poor solid–solid interface contact induced by the lithiophobic Li2CO3 layer hinder its practical application. Herein, a versatile strategy is proposed based on the hydrolysis of sodium tetrafluoroborate (NaBF4), aiming to convert the Li2CO3 into multifunctional hybrid layer containing LiF, LiBO2, and NaF. Among them, LiF and LiBO2 serve as the primary Li ion conductors, the introduction of NaF with high surface energy not only enhances the interface wettability, but also further elevates the critical dendrite strength against Li dendrites. All three components serve as excellent electronic insulators, suppressing electron invasion at the interface and preventing Li dendrite growth in the solid electrolyte. As expected, the interfacial impedance of the NaBF4 treated symmetric cell is reduced to 6.0 Ω cm2, the critical current density (CCD) comes to 2.0 mA cm−2, and cycles over 3000 h at 0.3 mA cm−2 and 1500 h at 0.5 mA cm−2 respectively. Besides, the modified SSBs matched with LiFePO4 or LiNi0.6Co0.2Mn0.2O2 cathode show great long‐term cycling and rate performance.

Defect Engineering Simultaneously Regulating Exciton Dissociation in Carbon Nitride and Local Electron Density in Pt Single Atoms Toward Highly Efficient Photocatalytic Hydrogen Production.

The high exciton binding energy (Eb) and sluggish surface reaction kinetics have severely limited the photocatalytic hydrogen production activity of carbon nitride (CN). Herein, a hybrid system consisting of nitrogen defects and Pt single atoms is constructed through a facile self-assembly and photodeposition strategy. Due to the acceleration of exciton dissociation and regulation of local electron density of Pt single atoms along with the introduction of nitrogen defects, the optimized Pt-MCT-3 exhibits a hydrogen production rate of 172.0µmolh-1 (λ ≥ 420nm), ≈41 times higher than pristine CN. The apparent quantum yield for the hydrogen production is determined to be 27.1% at 420nm. The experimental characterizations and theoretical calculations demonstrate that the nitrogen defects act as the electron traps for the exciton dissociation, resulting in a decrease of Eb from 86.92 to 43.20meV. Simultaneously, the stronger interaction between neighboring nitrogen defects and Pt single atoms directionally drives free electrons to aggregate around Pt single atoms, and tailors the d-band electrons of Pt, forming a moderate binding strength between Pt atoms and H* intermediates.

Transport of nanoscale zero-valent iron in the presence of rhamnolipid

Nanoscale zero-valent iron (nZVI) particles have gained widespread use for in-situ treatment of various chlorinated hydrocarbons. Their non-toxic nature, affordability, and minimal maintenance requirements have made them a favored material for nanoremediation. The treatment typically involves the injection of nZVI particles into contaminated sites using direct-push well injection systems. However, their small size leads to high surface energy, causing aggregation that alters their physiochemical properties, reactivity, and transport behavior. To counteract aggregation, nZVI suspension can be stabilized with different surfactants, reducing the surface energy during subsurface soil transport. This study investigates the impact of rhamnolipid, a biosurfactant produced by Pseudomonas aeruginosa during the late growth phase, on the aggregation and mobility of nZVI particles. The retardation factor of nZVI in the model media of zeolite, ZK406H, decreased from 1.66 in the absence of rhamnolipid to 1.03, 0.98, 0.93, and 0.87, corresponding to the presence of rhamnolipid at concentrations of 20, 50, 80, and 100 mg/L. The deposition coefficient also decreased from 2.39 in the absence of rhamnolipid to 0.459, 0.279, 0.217, and 0.0966, corresponding to the presence of rhamnolipid at concentrations of 20, 50, 80, and 100 mg/L. The transport parameters of nZVI in ZK406H were linked to the interactions of nZVI particles with ZK406H by the DLVO theory.

Achieving low-voltage operating high-mobility organic thin-film transistors by a multi-layered gate dielectric

Organic thin-film transistors (OTFTs) have attracted great attention for their inherent advantages and promising applications in emerging fields. Simultaneously realizing low-voltage operation and high-mobility in one OTFT is one of prerequisites for the commercialization, which is a huge challenge so far. An important route to address this challenge is to develop an ideal gate dielectric with a high capacitance and a low interfacial trap density at the dielectric/channel. In this Letter, we demonstrate the low-voltage operating high-mobility OTFTs by elaborately designing and processing a multi-layered gate dielectric. The gate dielectric consists of a high permittivity polymer film, a polymer buffing layer with a high surface energy, and an ultrathin long-chain alkane buffer layer. The effects of both the structures and the processes of gate dielectrics on the performances of OTFTs are investigated in detail. In addition, the relevant physical mechanisms are discussed. Finally, the optimal OTFTs exhibit high mobilities with the average and maximum values up to 5.62 and 6.74 cm2/V s, respectively, at low operating voltages below −5 V. Our findings reveal that designing and processing a reasonable multi-layered gate dielectric is a promising strategy to achieve both high-mobility and low-voltage operation in OTFTs, thereby fostering their development.

An approach to surface electron density-sensing property correlation in non-stoichiometric boron carbide

The key to most surface phenomena lies in the surface electron density. Particularly, it is the electron density distribution over the surface that primarily controls the overall interaction of the material with the external environment, say in processes like heterogeneous catalysis. Hence, a precise understanding of surface electron density is essential to understand and design improved surface active materials for catalysis and sensing. Surface structure has been determined primarily using surface sensitive techniques like high-energy surface x-ray diffraction (XRD), the crystal truncation rod scattering method, low-energy electron diffraction, scanning transmission electron microscopy, and grazing incidence small angle x-ray scattering. In this work, using aspherical electron density models of crystal structures in different molecular and extended solids, we show a convenient and complementary way of determining high-resolution experimental surface electron density distribution from conventional bulk x-ray diffraction data. The usefulness of our method has been validated by the surface functionality of boron carbide. While certain surfaces in boron carbide show the presence of substantial electron deficient centers, they are absent in others. Based on that, a new surface property of boron carbide has been inferred and has also been validated by chemiresistive gas sensing experiments.

Research on the Stability of Different Polar Surfaces in Aluminum Nitride Single Crystals

Wurtzite aluminum nitride (AlN) crystal has a non-centrosymmetric crystal structure with only a single axis of symmetry. In an AlN crystal, the electronegativity difference between the Al atom and N atom leads to a distortion of electron cloud distribution outside the nucleus and a spontaneous polarization (SP) along the c-axis direction. The N-polar surface along the directions of [000-1] has higher surface energy than the Al-polar surface along the directions of [0001]. Due to the different atomic arrangement, Al atoms on the Al-polar surface bond with O and OH− in the environment to generate Al2O3·xH2O, which prevents the reaction from occurring inside the crystal. After the Al2O3·xH2O dissolve in an alkaline environment, N atoms have three dangling bonds exposed on the surface, which can also protect OH− from destroying the internal Al-N bonds, so the Al-polar surface is more stable than the N-polar surface.

Optimizing Paclitaxel Oral Absorption and Bioavailability: TPGS Co-Coating via Supercritical Anti-Solvent Fluidized Bed Technology.

Supercritical anti-solvent fluidized bed (SAS-FB) coating technology has the advantages of reducing particle size, preventing high surface energy particle aggregation, improving the dissolution performance and bioavailability of insoluble drugs. The poor solubility of Biopharmaceutics Classification System (BCS) class IV drugs poses challenges in achieving optimal bioavailability. Numerous anti-cancer drugs including paclitaxel (PTX) belong to the BCS class IV, hindering their therapeutic efficacy. To address this concern, our study explored SAS-FB technology to coat PTX with D-α-tocopherol polyethylene glycol 1000 succinate (TPGS) onto lactose. Under our optimized conditions, we achieved a PTX coating efficiency of 96.8%. Further characterization confirmed the crystalline state of PTX in the lactose surface coating by scanning electron microscopy and X-ray powder diffraction. Dissolution studies indicated that SAS-FB processed samples release over 95% of the drug within 1 min. Moreover, cell transmembrane transport assays demonstrated that SAS-FB processed PTX samples co-coated with TPGS had an enhanced PTX internalization into cells and a higher permeability coefficient compared to those without TPGS. Finally, compared to unprocessed PTX, SAS-FB (TPGS) and SAS-FB processed samples showed a 2.66- and 1.49-fold increase in oral bioavailability in vivo, respectively. Our study highlights the efficacy of SAS-FB co-coating for PTX and TPGS as a promising strategy to overcome bioavailability challenges inherent in BCS class IV drugs. Our approach holds broader implications for enhancing the performance of similarly classified medications.

Sm3+ doping-adjusted mechanical, dielectric, and radiation shielding properties of cobalt copper nanoferrites

The scarcity of research on the shielding properties of spinel ferrites underscores the necessity for more rigorous investigations. Consequently, this study introduces a facile synthesis method for Co, Cu, and Sm spinel nanoferrites (referred to as CCS nanoferrites) using the citrate combustion technique. The investigation focuses on their mechanical, dielectric, and gamma-ray shielding parameters. Gamma-ray shielding features are obtained theoretically via the Phy-X database. The particle size, nature, and distribution of the present CCS nanoferrites were analyzed using HR-TEM microscopy. HR-TEM results reveal both the spherical shapes and the aggregation of nanoparticles. These observations can be attributed to the interplay of high surface energy and magnetic interactions among the components of the CCS nanoferrites. The Co0.5Cu0.5Sm0.15Fe1.85O4 nanoferrite exhibits an optimal dielectric constant value of 4587, with an enhanced ratio of 1618% compared to the pristine CCS0 sample. Additionally, it demonstrates an optimal conductivity of 38.59 μ (Ω·m)−1, with an enhanced ratio of 1105%. Furthermore, the loss is reduced to 2.65, showing an improvement ratio of 54% compared to the pristine nanoferrite at room temperature and 50 Hz. Moreover, the longitudinal modulus, shear modulus, Young's modulus, and bulk modulus of the nanoferrite Co0.5Cu0.5Sm0.15Fe1.85O4 were increased from 1.79 to 4.96 GPa, 0.32–0.93 GPa, 0.88–2.56 GPa, and 1.37–3.73 GPa, respectively, when compared to the pristine sample. The comparative study of half-value layers at 0.662 MeV revealed that CCS nanoferrites exhibit smaller half-value layers than common radiation shielding materials. Additionally, the study highlighted the enhanced radiation shielding performance of the nanoferrites. Concerning the dielectric, mechanical, and ionizing radiation shielding properties of the CCS spinel nanoferrites, the CCS5 (with the highest Sm content) has the optimum ionizing radiation shielding ability with the highest dielectric and mechanical parameters compared to the other samples. The implications of these findings extend to potential applications in biomedicine, radiation protection, and the optimization of electronic devices operating in radiation fields.

2D magnetic nanoporous carbon with bridge-type aptamer assembly for pesticide detection based on a regenerative field-effect transistor biosensor

Field-effect transistor (FET)-based biosensors have garnered attention due to their sensitivity to surface charge changes and advantages in real-time detection. However, these biosensors often suffer from several disadvantages such as their limited sensitivity and a high cost. Here, we reported an ultra-sensitive and reusable nanoporous-based FET biosensor hybridized with bridge-type aptamers. The sensor consisted of a two-dimensional magnetic iron-cobalt nanoparticle-embedded nanoporous carbon (Fe-Co/NPC) functionalized with bridge-type aptamers. The edges of the nanopores exhibited high surface energy and chemical activity, enabling effective interactions with the aptamers. Moreover, the nanoporous structures provided additional space, which could improve molecular recognition sites and sensor sensitivity. Our sensor could be used to detect organophosphorus pesticides (OPs) in vegetables down to 100 fM in real time and identify OPs from other pesticides. Furthermore, the magnetic properties of Fe-Co/NPC allowed us to reuse a single sensor chip up to 8 times, which significantly reduced the production cost of our sensors. In this respect, our Fe-Co/NPC-FET sensor could be a powerful tool for practical applications such as food safety detection.

Synergistic adsorption-photocatalysis effect of α-Fe2O3-loaded acyl chloride-covalent organic framework (AC-COF) @MIL-101 porous composites for boosted tetracycline removal

The tendency of small-sized covalent organic framework (COF) nanoparticles to easily agglomerate, and the propensity of photo-generated carriers in α-Fe2O3 to recombine pose challenges in the efficient removal of tetracycline (TC) through adsorption-photocatalysis synergy. This study addresses these challenges by introducing MIL-101, known for its excellent chemical stability and large specific surface area. The amino functional group facilitates the in-situ growth of acyl chloride-covalent organic framework (AC-COF) on the surface of MIL-101, resulting in the fabrication of AC-COF@MIL-101 with a core-shell structure. Loading α-Fe2O3 through structural regulation leads to the preparation of the final α-Fe2O3/AC-COF@MIL-101 ternary nanocomposite. In α-Fe2O3/AC-COF@MIL-101 composites, the high surface energy of AC-COF is mitigated by the strong chemical energy of NC-N, reducing AC-COF aggregation and decreasing the recombination rate of photogenerated carriers in α-Fe2O3. The heterojunction structure between AC-COF@MIL-101 and α-Fe2O3 enhances the degradation of TC, attributed to the synergistic effect of adsorption and photocatalysis. Experimental results demonstrate that α-Fe2O3/AC-COF@MIL-101 has a maximum adsorption capacity of 135.14 mg/g, achieving a 100% TC removal rate within 30 min. Compared to AC-COF, MIL-101, and α-Fe2O3, α-Fe2O3/AC-COF@MIL-101 exhibits higher adsorption capacity and photocatalytic activity. Specifically, its adsorption capacity is 2.1 times that of AC-COF, 1.8 times that of MIL-101, and 10.6 times that of α-Fe2O3. Additionally, its degradation ability is 8.6 times that of α-Fe2O3. The adsorption of TC by α-Fe2O3/AC-COF@MIL-101 occurs through monolayer chemical adsorption, and the process is exothermic. The main active species involved in the photocatalytic degradation process are h+ and ·OH. This study introduces a new ternary composite multifunctional material with high adsorption and photocatalytic performance for TC, offering a potential strategy for enhancing the synergistically adsorption-photocatalytic effect in ternary composite systems.

Magnetic CuFe2O4 nanoparticles immobilized on mesoporous alumina as highly efficient peroxymonosulfate activator for enhanced degradation of tetracycline hydrochloride

Nanoscaled magnetic copper ferrite (CuFe2O4) is widely used as a peroxymonosulfate (PMS) activator but suffers from agglomeration owing to its inherent magnetic properties and high surface energy. In this work, spinel structured CuFe2O4 anchored on mesoporous alumina (denoted as CFO@AO) were synthesized, characterized, and applied as a PMS activator for the removal of tetracycline hydrochloride (TC·HCl). Approximately 97.5 % of TC·HCl was decomposed within 10 min in 30 %–CFO@AO (0.2 g/L)/PMS (0.3 g/L) system, and the corresponding kinetic rate constant of 30 %–CFO@AO/PMS (0.417 min−1) was around 1.57 times higher than that of CuFe2O4/PMS (0.266 min−1), which indicating that the existence of synergistic catalysis between CuFe2O4 and Al2O3 enhanced the degradation of TC·HCl. Moreover, nano-sized CuFe2O4 were successfully anchored on the surface of Al2O3 because of FeOAl bond, which could account for the enhanced catalytic activity, superior pH flexibility, and high chemical stability and reusability of 30 %–CFO@AO. Quenching experimentals, electron paramagnetic resonance, and methyl phenyl sulfoxide (PMSO) chemical probe assays confirmed that both radical oxidation (OH) and non-radical oxidation (1O2 and Fe(IV)O) were proposed in the developed CFO@AO/PMS system, and OH played a key role in the process. Meanwhile, the PMS activation mechanism by CFO@AO composite was also analyzed based on the results of adsorption energy, which was calculated via DFT. Based on UPLC–MS technique, a possible degradation pathway for TC·HCl destruction in 30 %–CFO@AO/PMS system was proposed. The toxicity assessment showed that the catalytic degradation of TC·HCl in 30 %–CFO@AO/PMS system reduced the toxicity of most of degradation intermediates. Present work proved that CuFe2O4@Al2O3 composite is an efficient, environment-friendly, and recyclable heterogeneous catalyst for practical wastewater treatment via PMS activation.

Oriented Growth of Parallel‐Standing Bimetallic Nanosheet Arrays for Enhanced Charge Transfer

AbstractFabricating highly oriented 2D nanosheet arrays is crucial for boosting their performance in electronics, catalysis, optics, and energy conversion, while it remains a challenge due to the high surface energy often leads to random aggregation or interlaced structure. In this study, it is found that the exposed facet of Fe2O3 can greatly influence the interface growth arrangement of bimetallic hydroxide (NiCo(OH)2) nanosheets. The NiCo(OH)2 nanosheets tend to parallel‐standing on the cubic and spindle Fe2O3 while random‐ and interlaced‐standing on the Fe2O3 hexagonal nanoplates and microspheres. The theoretical simulation further indicates the orientation of deposited hydroxide sheets is decided explicitly by the interfacial lattice match/mismatch. Compared to the common interlaced structure of nanosheets, the parallel‐standing nanosheet arrays reduce grain boundaries and improve the charge transfer efficiency. As a result, the derived NiCoP cages exhibit a promising oxygen evolution reaction performance with an overpotential of 255 mV at 10 mA cm−2, and the maximum current density of 400 mA cm−2 with the overpotential of 319 mV.

Design of Abrasion-Resistant, Long-Lasting Antifog Coatings.

Fog formation is a common challenge for numerous applications, such as food packaging, mirrors, building windows, and freezer/refrigerator doors. Most notably, fog forms on the inner surfaces of prescription glasses and safety eyewear (particularly when used with a mask), face shields, and helmet lenses. Fogging is caused by the distortion of light from condensed water droplets present on a surface and can typically be prevented if the surface static water contact angle (θ) is less than ∼40°. Such a low contact angle can be readily achieved by either increasing the substrate surface energy or by engineering surface nanotexture. Unfortunately, such nanotexture can be readily damaged with use, while high surface energy substrates get covered with low surface energy foulants over time. Consequently, even with numerous ephemeral antifog coatings, currently there are no commercially available, durable, and permanent antifog coatings. Here we discuss the development of a new class of high-performance antifog coatings that are abrasion-resistant and long-lasting. These polyvinylpyrrolidone-based coatings, designed based on the classical Ratner-Lancaster wear model, dramatically outperform the base polymer, as well as all tested commercially available antifog coatings. Specifically, these coatings exhibit a > 400% increase in fogging time compared to base polymer, a > 50,000% increase in wear resistance, and excellent long-term antifog performance. The developed coatings also significantly outperformed all tested commercially available antifog coatings in terms of their antifog performance, wear resistance, and long-term cyclical performance. Additionally, the key design strategies employed here─incorporation of toughening agents and hydrophilic slip additives─offer a new approach to developing high-performance, durable antifog coatings based on other well-known antifog polymers.

Enhanced oxidase mimic activity of raspberry-like N-doped Mn3O4 with oxygen vacancies for efficient colorimetric detection of gallic acid coupled with smartphone

The content of gallic acid (GA) is positively correlated with the quality grade of tea. Here, we developed a colorimetric method based on raspberry-like N-doped Mn3O4 nanospheres (N-Mn3O4 NSs) with oxidase-like activity for GA assay. Modulating the electronic structure of Mn3O4 by N doping could promote the catalysis ability, and the produced oxygen vacancies (OVs) can provide high surface energy and abundant active sites. The N-Mn3O4 NSs presented low Michaelis-Menten constant (Km) of 0.142 mM and maximum initial velocity (Vmax) of 9.8 × 10−6 M s−1. The sensor exhibited excellent analytical performance towards GA detection, including low LOD (0.028 μM) and promising linear range (5 ∼ 30 μM). It is attributed that OVs and O2− participated in TMB oxidation. Based on the reaction color changes, a visualized semi-quantitative GA detection could be realized via a smartphone-based system. It could be applied for evaluating GA quality in market-purchased black tea and green tea.

The Facile Construction of Anatase Titanium Dioxide Single Crystal Sheet-Connected Film with Observable Strong White Photoluminescence

Deposited by a reactive atmospheric pressure non-thermal TiCl4/O2/Ar plasma, anatase TiO2 single crystal sheet-connected film exhibits two large exposed {001} facets and a high concentration of oxygen defects. Strong white photoluminescence centered at 542 nm has been observed with naked eyes, whose internal quantum efficiency is 0.62, and whose intensity is comparable to that of commercial fluorescent lamp interior coatings. Based on the simulation results of a hybrid global–analytical model developed on this atmospheric pressure non-equilibrium plasma system, the mechanism of a self-confined growth of single crystal sheets was proposed. A high concentration of oxygen defects is in situ incorporated into the anatase crystal lattice without damaging its crystallographic orientation. This method opens a new way to construct 3D porous metal-oxide single crystal sheet-connected films with two exposing high energy surfaces and a large concentration of oxygen defects.

Ultrafast Quasi‐2D/3D Perovskite Photodetectors Conferred Using Interfacial Engineering of Self‐Assembled Monolayers

AbstractQuasi‐2D (q‐2D) perovskites are extensively studied due to their hybrid properties of 3D and 2D phases and have proven to be applied to a wide range of optoelectronics. Multiple device engineering methods for perovskite photodetectors are developed. However, the treatment of self‐assembled monolayer (SAM) is rarely discussed. Herein, a series of silane‐coupling agents of (3‐chloropropyl)trichlorosilane (CPTS), phenyltrichlorosilane, and (3‐aminopropyl)triethoxysilane is adopted as SAM materials and elucidated their influence on q‐2D/3D CsPbBr3 films and their photodetector performance. The optical properties and morphology results reveal that perovskite film on CPTS‐modified surface can prolong excitons’ lifetime, produce a larger grain size and better size distribution, while also present better crystallinity and united orientation. As for the fabricated photodetectors, the device on a CPTS‐modified surface has the highest photocurrent of 5.46 × 10−8 A, a responsivity of 0.16 A W−1, and an 18‐times‐higher specific detectivity than the pristine counterpart, which comes from the higher surface energy and favorable energy level alignment. The photodetector on the CPTS‐modified surface also shows better stability than that on the pristine surface. This study pioneers by using SAMs on q‐2D perovskite photodetectors and provides a facile route of device fabrication for perovskite photodetectors.

Polymeric liquids in mesoporous photonic structures: From precursor film spreading to imbibition dynamics at the nanoscale

Polymers are known to wet nanopores with high surface energy through an atomically thin precursor film followed by slower capillary filling. We present here light interference spectroscopy using a mesoporous membrane-based chip that allows us to observe the dynamics of these phenomena in situ down to the sub-nanometer scale at milli- to microsecond temporal resolution. The device consists of a mesoporous silicon film (average pore size 6 nm) with an integrated photonic crystal, which permits to simultaneously measure the phase shift of thin film interference and the resonance of the photonic crystal upon imbibition. For a styrene dimer, we find a flat fluid front without a precursor film, while the pentamer forms an expanding molecular thin film moving in front of the menisci of the capillary filling. These different behaviors are attributed to a significantly faster pore-surface diffusion compared to the imbibition dynamics for the pentamer and vice versa for the dimer. In addition, both oligomers exhibit anomalously slow imbibition dynamics, which could be explained by apparent viscosities of six and eleven times the bulk value, respectively. However, a more consistent description of the dynamics is achieved by a constriction model that emphasizes the increasing importance of local undulations in the pore radius with the molecular size and includes a sub-nanometer hydrodynamic dead, immobile zone at the pore wall but otherwise uses bulk fluid parameters. Overall, our study illustrates that interferometric, opto-fluidic experiments with mesoporous media allow for a remarkably detailed exploration of the nano-rheology of polymeric liquids.