Interfacial Coordination Research Articles

Interfacial coordination mediated surface segregation of halloysite nanotubes to construct a high-flux antifouling membrane for oil-water emulsion separation

Forced surface segregation of hydrophilic nanoparticles on the hydrophobic polymer matrix is considered as the effective strategy to fabricate high performance hybrid membrane for oil/water separation. In this work, the halloysite nanotubes (HNTs) were successively modified with dopamine (PDA) and tannic acid (TA) coatings to obtain the hydrophilic nanoparticles (NPs) of HNTs-DA-TA. Next, the obtained HNTs-DA-TA NPs were blended with polyethersulfone (PES) to prepare the oil/water separation membrane via the phase inversion in the coagulation bath containing Fe3+. We have found that the interfacial coordination between TA and Fe3+ is able to enhance the surface segregation of hydrophilic HNTs-DA-TA NPs on hydrophobic PES membrane, which not only contributes to the formation of asymmetric porous membrane, but also can prevent the loss of nanotubes during the phase transitions. Thanks to these advantages, the water flux of nanocomposite membranes was significantly increased (up to 682 L m-2 h-1), which was ~3.4 times than that of the pristine PES membrane (199 L m-2 h-1), whereas the rejection was still kept at a high state. After three cycles of separation, the water flux recovery rate can reach up to 91%, which was also much higher than 56% of the pristine PES.

Highly efficient removal of cationic, anionic and neutral dyes by hierarchically porous structured three-dimensional magnetic sulfur/nitrogen co-doped reduced graphene oxide nanohybrid

The versatile three-dimensional magnetic sulfur/nitrogen co-doped reduced graphene oxide nanomaterials (3D-MSNGs) have been constructed and generated via interfacial coordination assembly of three-dimensional sulfur/nitrogen dual-doped reduced graphene oxide (3D-SNG) with concurrent modification by formed magnetic Fe3O4. Using ferric ions as iron source, the as-obtained nanohybrid 3D-MSNG-1 possesses abundant hierarchical porous structure on graphene network, large BET surface area and favorable magnetic properties, which is proved excellent adsorption capacity and easy magnetic separation. When 3D-MSNG-1 was utilized to absorb the dyes of methylene blue (MB), congo red (CR) and neutral red (NR) considered as cationic, anionic and neutral model dye molecules, respectively, the adsorption equilibrium for MB, CR and NR were rapidly achieved in 15 min. The adsorption isotherm fits Langmuir adsorption model well with the maximum uptake capacity for MB, CR and NR high to 171.53 mg/g, 909.09 mg/g and 877.19 mg/g, respectively. Meanwhile, an efficacious treatment of ternary dyes mixed solution and a good recyclability manifests that 3D-MSNG-1 is supposed to be a superior adsorbent in the areas of water treatment.

Interfacial Coordination Nanosheet Based on Nonconjugated Three-Arm Terpyridine: A Highly Color-Efficient Electrochromic Material to Converge Fast Switching with Long Optical Memory.

An electrochromic (EC) hyperbranched coordination nanosheet (CONASH) comprising a three-arm terpyridine (3tpy)-based ligand and Fe(II) ion has been synthesized by interfacial complexation at the liquid-liquid interface. The film can be easily deposited on the desired substrate such as indium tin oxide (ITO) glass. Characterization of CONASH deposited on ITO by microscopic methods reveals the homogeneous nanosheet film with an ∼350 nm thickness after 48 h of reaction. The fabricated solid-state EC device (ECD) undergoes a reversible redox reaction (Fe2+ → Fe3+) in the potential range of +3 to -2 V in ECDs accompanied with a distinct color change from intense pink to colorless for several switching cycles with a coloration time of 1.15 s and a bleaching time of 2.49 s along with a high coloration efficiency of 470.16 cm2 C-1. Besides, the nonconjugated 3tpy ligand restricts the easy electron redox conduction inside the EC film to enhance the EC memory in open-circuit condition as it shows 50% retention of its colorless state until 25 min. The long EC memory compared to other metallo-supramolecular polymers having a conjugated ligand suggests the potentiality of the 3tpy-Fe CONASH film to be used as a power-efficient EC material for modern display device applications.

Two-photon absorbing performance and interfacial coordination enhanced mechanism of TPPA-CdS hybrid

A novel organic/inorganic hybrid which consisted of N,N-diphenyl-4-(2,2':6′,2″-tepyridin-4-yl)aniline (abbreviated as TPPA) and CdS nanoparticles (NPs) had been prepared through interfacial coordination effect according to soft-hard-acid-base principle. The interfacial coupling coordination was analyzed by XRD, far-IR, FT-IR and HRTEM, which resulted in changeable morphology and tunable linear/nonlinear optical properties. Upon interfacial coordination, the hybrid showed a red-shifted (55 nm) UV–vis absorption band, weakened single photon fluorescence emission (84% decrease), and enhanced two-photon absorption cross-section (13 folds). Due to excellent two-photon absorbing character, the hybrid had good application in the field of optical power limiting with 43 W⋅cm−2 limiting threshold. The regulation mechanism of optical properties was thoroughly discussed upon single crystal structure of the interfacial coordination complex and quantum calculation, as well as the growing mechanism of the hybrid.

Ions Tune Interfacial Water Structure and Modulate Hydrophobic Interactions at Silica Surfaces.

The structure and ultrafast dynamics of the electric double layer (EDL) are central to chemical reactivity and physical properties at solid/aqueous interfaces. While the Gouy-Chapman-Stern model is widely used to describe EDLs, it is solely based on the macroscopic electrostatic attraction of electrolytes for the charged surfaces. Structure and dynamics in the Stern layer are, however, more complex because of competing effects due to the localized surface charge distribution, surface-solvent-ion correlations, and the interfacial hydrogen bonding environment. Here, we report combined time-resolved vibrational sum frequency generation (TR-vSFG) spectroscopy with ab initio DFT-based molecular dynamics simulations (AIMD/DFT-MD) to get direct access to the molecular-level understanding of how ions change the structure and dynamics of the EDL. We show that innersphere adsorbed ions tune the hydrophobicity of the silica-aqueous interface by shifting the structural makeup in the Stern layer from dominant water-surface interactions to water-water interactions. This drives an initially inhomogeneous interfacial water coordination landscape observed at the neat interface toward a homogeneous, highly interconnected in-plane 2D hydrogen bonding (2D-HB) network at the ionic interface, reminiscent of the canonical, hydrophobic air-water interface. This ion-induced transformation results in a characteristic decrease of the vibrational lifetime (T1) of excited interfacial O-H stretching modes from T1 ∼ 600 fs to T1 ∼ 250 fs. Hence, we propose that the T1 determined by TR-vSFG in combination with DFT-MD simulations can be widely used for a quantitative spectroscopic probe of the ion kosmotropic/chaotropic effect at aqueous interfaces as well as of the ion-induced surface hydrophobicity.

Binding Modes of Salicylic Acids to Titanium Oxide Molecular Surfaces.

A set of titanium oxide clusters (TOCs) comprised of 4 to 16 Ti atoms are synthesized with substituted salicylates (SSAs). The interfacial coordination environment of these SSA/Ti oxide hybrids are surveyed and found to be limited to four binding modes, with the bridging chelate mode being the most common one. The SSA-functionalized TOCs show strong visible light absorption properties. The contribution of the SSAs in the frontier orbitals of the TOCs are analyzed by using TD-DFT calculations based on the molecular geometries determined by X-ray diffraction. For TOCs of relatively high O/Ti ratio, the SSAs narrow the band gap of the TOCs by contributing solely to the HOMOs. Both binding modes and locations of the SSAs are important for the roles of SSAs in changing the HOMOs and thereby the absorption onsets.

An efficient g-C3N4-decorated CdS-nanoparticle-doped Fe3O4 hybrid catalyst for an enhanced H2 evolution through photoelectrochemical water splitting

We developed a highly efficient and stable g-C3N4-decorated CdS-nanoparticle-doped Fe3O4 nanocube catalyst, g-C3N4@CdS–Fe3O4 (gCNCSF), with a two-step solvo-thermal process in an aqueous phase. It enhanced H2 evolution via photoelectrochemical (PEC) water splitting. Melamine and isolated onion leaf extract were used to prepare g-C3N4 by calcination under an N2 atmosphere at 450 °C. Subsequently, a CdS@Fe3O4 catalyst was fabricated by doping CdS nanoparticles into the interfacial layers of Fe3O4, via a hydrothermal method, following calcination at 450 °C under N2. According to the PEC analysis, the gCNCSF catalyst exhibited a photo-current density of 0.023 mA/cm2, approximately 2.5 and 6.25 times higher than those of binary hybrids g-C3N4@CdS and CdS@Fe3O4, respectively. In addition, approximately 4.1 and 27.7 times higher performance has been recorded than those of neat CdS and g-C3N4, respectively. This was at an applied bias potential of 0.2 V vs. Ag/AgCl. The high rate of H2 evolution could be attributed to the interfacial coordination between g-C3N4 and CdS nanoparticles doped in the Fe3O4 nanocubes, which eventually promoted the bandgap-dependent interfacial charge transfer.

Controlling morphology and catalysis capability of Sn/Ce porous coordination polymers by cerium coordination for catalytic conversion of glucose to 5-hydroxymethylfurfural

Abstract A novel porous coordination polymer (namely SnCe) has been synthesized by simultaneous coordination of Tin (Sn (IV)) and cerium (Ce (III/IV)) with the two ligands 5-sulfoisophthalic acid (SPA) and 1,3,5-benzenetricarboxylic acid (BTC). The morphology and surface area of SnCe can be controlled by the cerium-involved interfacial coordination, by taking advantage of the discrepancy of coordination ability between the two metal ions. The shape and size of the SnCes has a close relationship with the molar ratio of Sn to Ce. The mechanism of the formation of SnCe was investigated by electron microscopy measurement (scanning electron microscope) and XRD patterns. The catalysis capability was also controlled, with Sn (IV) and Ce (III/IV) as the Lewis acid sites and the sulfonate groups of SPA as the Bronsted acid sites. The Lewis acid sites can catalyze isomerization of glucose into fructose, and the Bronsted acid sites can catalyze the dehydration of fructose to 5-hydroxymethylfurfural (HMF) with a high efficiency. Thus, SnCe combines the bifunctional catalysis capability for producing HMF (an important platform chemical) from glucose. This work found that the morphology of catalyst has an effect on the catalyst capability. At the similar reaction conditions, the catalyst exhibits higher conversion and selectivity than those reported.

Multiple crosslinking strategy to achieve high bonding strength and antibacterial properties of double-network soy adhesive

The development of high-performance and sustainable bio-based adhesives has become a significant strategy for solving concerns regarding environmental pollution, resource utilization, and public health in the material engineering and production industries. In this work, hyperbranched silicone was prepared and reacted with a catecholamine-based tannic acid and soybean meal to obtain a strong and antibacterial bio-based adhesive having a hyperbranched cross-linked structure. In addition, versatile copper ions were introduced into the adhesive to form multiple interfacial coordination bonds. The resulting intertwined dual network of metal coordination bonds and covalent crosslinks in the adhesive system improved the cross-link density and cohesive interactions of the adhesives, enhancing their adhesion strength and water resistance. The maximum wet shear strength of the modified adhesive was 1.27 MPa, which was 309.68% higher than that of the pristine adhesive. Sol-gel test showed that the swelling ratio of the modified adhesive decreased from 413.8% to 52.4%, while the insoluble fraction increased by 16.47%. Furthermore, the resulting adhesives exhibited a high bacterial resistance against Staphylococcus aureus and Escherichia coli. The formation of an intertwined dual network in a bio-based adhesive to achieve excellent properties is a promising approach for the fabrication of sustainable eco-friendly biopolymer materials from agricultural byproducts used to achieve a cleaner production.

Phase-mediated robust interfacial electron-coupling over core-shell Co@carbon towards superior overall water splitting

The development of bifunctional electrocatalysts is an appealing yet challenging task for renewable energy conversion. Herein, taking core-shell structure as an example, we propose a “phase mediation” strategy to boost electronic synergism on hydrogen and oxygen evolution reaction (HER/OER). Through precisely tuning the cobalt cores from face-centered-cubic (fcc) to hexagonal (hcp) structure, the electrocatalytic overpotentials of Co@NC for both HER and OER are reduced by ∼100 mV, and lower than those of most other carbon-based electrocatalysts yet reported. Operando SR-FTIR measurements uncover key intermediates of *H and *OO bonding to N and C sites of CN moieties in hcp-Co@NC during the HER and OER processes, respectively, suggesting the adjacent CN moieties as synergistic active sites. In addition, atomic-level characterizations combined with theoretical calculations reveal robust interfacial metal-ligand coordination and electron injection effect within hcp-Co@NC. This promotes the delocalization of electronic structure of the NC shell, greatly accelerating overall water splitting.

Interfacial coordination assembly of tannic acid with metal ions on three-dimensional nickel hydroxide nanowalls for efficient water splitting

Interfacial coordination of tannic acid with metal ions enables conformal coating on nickel hydroxide nanowalls for enhancing the water-splitting performance.

MOF-derived Co3O4 nanosheets rich in oxygen vacancies for efficient all-solid-state symmetric supercapacitors

Co3O4 is a promising pseudocapacitive material with a high theoretical capacity. We demonstrate herein a facile interfacial engineering toward Co-metal organic frameworks (Co-MOFs) derived Co3O4 nanosheets for improving the overall capacitive performance. Firstly, a thin hydrophilic carbon layer was coated onto carbon cloth (CC) to stablize the interfacial coordination effect between Co3O4 and carbon fibres. Secondly, oxygen vacancies by reducing Co3O4 was introduced to improve the electron and ions transfer on the interface between Co3O4 and electrolyte. The unique Co3O4 structure and composition endow the optimal v-Co3O4/CC composite with significantly improved specific capacity (414 C g−1 at 1 A g−1) and excellent stability (0.00174% capacity loss per cycle for 15000 cycles). Asymmetric supercapacitor by assembling v-Co3O4/CC composite as positive electrode with the same MOF derived carbon nanosheets as negative electrode demonstrates a high volumetric and gravimetric energy density of 0.74 mWh cm−3 (14.7 mW cm−3) and 45.3 Wh kg−1 (915 W kg−1), respectively. This work might provide a simple but efficient approach for boosting the pseudocapacitive performance of transition metal oxides.

Two-photon fluorescent detection of Cu2+ in live cells through ZnS-microhybrid constructed from interfacial coordination bridge of thiocyanate

Copper is an indispensable part of production and life. Accordingly, detection of Cu2+ in cells is of great significance to human health. In this work, we report the development of a two photon fluorescent ZnS-TPYPA microhybrid consisted of ZnS particles and terpyridine derivative 4-([2,2':6′,2″-terpyridin]-4′-yl)-N,N-diphenylaniline (TPYPA). The hybrid has been prepared according to interfacial coordination effect through SCN− ions as the coordination bridge. TPYPA gives the hybrid two-photon excited fluorescent(TPEF) character to achieve the TPEF-detection of Cu2+. The existence of ZnS attributes to the increase in TPA performance, optimize fluorescent selectivity, excellent detection limit (60 nmol L−1) and the application in vitro. The detection mechanism was discussed in detail, through both the optical properties and high resolution morphology at the interface.

Understanding the interfacial interactions of bioinspired chitosan-calcite nanocomposites by first principles molecular dynamics simulations and experimental FT-IR spectroscopy

The interfacial structures and bonding mechanism of the adsorption of chitosan monomers (GlcN and GlcNAc) on calcite (104) surface are investigated using first principles molecular dynamics simulations. It is revealed that the strong coordination CaO bonds are formed between five-fold coordinated Ca atoms on calcite surface and O atoms of hydroxyl groups (OH) and acetyl groups of chitosan in the chitosan-calcite nanocomposites, improving the chemical compatibility between organic and inorganic phases at the interface in the natural occurring nacre. Although, the presence of interfacial hydrogen bonds is also confirmed by analyzing the valence electron density difference in terms of induced dipole, the evolution of the equilibrium adsorption geometry is found to be mainly governed interfacial CaO coordination bonds. The amide group (NH2) of chitosan binds with calcite at the interface mainly through the formation of weak hydrogen bond. The predicted interfacial electronic structure can be either conductive (GlcNAc) or insulating (GlcN). The frequencies of the characteristic peaks in the calculated total and partial vibrational densities of states of GlcN/calcite systems are found to be in agreement with the FT-IR spectrum of the experimentally prepared chitosan-calcite nanocomposites, crucially validating the modelling structures and computational methodology employed in current work. Theoretical results strongly indicate that the peculiar adsorption in FT-IR spectrum at 2500 cm−1 is related to the presence of free GlcN molecule due to the hydrolysis of chitosan in aqueous solution.

Regulation of optical properties for fluorescent triphenylamine-silver hybrid based on SPR effect.

In this study, a two photon absorbing (TPA) material consisting silver nanoparticles and triphenylamine-thiol derivative (TBS) has been prepared through interfacial coordination effect according to soft-hard-acid-base principle. The interfacial structure and morphology of the hybrid are researched in detail. Linear and nonlinear optical properties of the hybrid are studied. Upon interfacial coordination, the hybrid shows red-shifted UV-Vis absorption, causing from enhanced electronic drawing strength due to existence of Ag atom. The results also indicate that the surface Plasmon resonance (SPR) effect of Ag nanoparticles (~6 nm) brings about enhancement in single photon fluorescence emission and two photon absorption. Compared with free TBS, Ag-TBS hybrids show higher TPA cross-section (δ), which is 8784 GM for TBS and up to 103876 GM for Ag-TBS hybrid, showing ~12 fold increase. Due to excellent TPA property, the hybrids have good application in the field of optical power limiting and its limiting threshold is 0.49 J/cm-2. This type of interfacial coordination induced hybrid provides a promising strategy to regulate linear optical properties and optimize nonlinear performance.

Enhancement of mechanical and biological properties of calcium phosphate bone cement by incorporating bacterial cellulose

ABSTRACTLow mechanical strength of calcium phosphate cement (CPC) limits its clinical application as a bone replacement. Herein, for the first time, we selected bacterial cellulose (BC) fibres to reinforce CPC. The BC-reinforced CPC (BC/CPC) composites with varying BC content were prepared and compared in terms of microstructure, compressive strength and cellular responses. Scanning electron microscope (SEM) images revealed the uniform dispersion of BC in CPC matrix. Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) results confirmed the interfacial coordination interaction between BC and CPC. It was found that the introduction of BC enhanced the compressive strength of CPC, and the optimal BC content was 2 wt.%. Moreover, cell studies showed that BC/CPC composites exhibited better cell performance than bare CPC. The results have demonstrated that a new CPC composite with enhanced mechanical performance and cellular responses may be developed by using BC as reinforcement.

Scalable Manufactured Self-Healing Strain Sensors Based on Ion-Intercalated Graphene Nanosheets and Interfacial Coordination.

Desirable mechanical strength and self-healing performance are very important to highly sensitive and stretchable sensors to meet their practical applications. However, balancing these two key performance parameters is still a great challenge. Herein, we present a simple, large-scale, and cost-efficient route to fabricate autonomously self-healing strain sensors with satisfactory mechanical properties. Specifically, ion-intercalated mechanical milling was utilized to realize the large-scale preparation of graphene nanosheets (GNs). Then, a well-organized GN-nanostructured network was constructed in a rubber matrix based on interfacial metal-ligand coordination. The resultant nanocomposites show desirable mechanical properties (∼5 times higher than that of control sample without interfacial coordination), excellent self-healing performance (even healable in various harsh conditions, for example, underwater, at subzero temperature or exposed in acidic and alkaline conditions), and ultrahigh sensitivity (gauge factor ≈ 45 573.1). The elaborately designed strain sensors offer a feasible approach for the scalable production of self-healing strain-sensing devices, making it promising for further applications, including artificial skin, smart robotics, and other electrical devices.

Metal-organic composite membrane with sub-2 nm pores fabricated via interfacial coordination

A metal-organic composite membrane with sub-2 nm pores was developed via interfacial coordination reaction in biphasic systems for the first time. Herein, tannic acid (TA) was dissolved in water, as aqueous phase; iron(III) acetylacetonate (Fe(acac)3), used as Fe(III) source, was dissolved in n-hexane as organic phase. A detailed study was conducted to obtain the defect-free TA-Fe(III) separation layer, including the salt concentration in aqueous solution, pH of the aqueous solution and the ratio of TA to Fe(acac)3. The results indicated that the defect-free TA-Fe(III) composite membrane formed when the tris-complex (TA3-Fe(III)) was achieved. The optimal condition for preparing TA-Fe(III) composite membrane was using aqueous solution containing 0.4 M NaCl at pH = 6 with the ratio of TA to Fe(acac)3 of 10. Different from the typical separation layer formed on the membrane surface by interfacial polymerization, the TA-Fe(III) separation layer was formed in the pores of the substrate, which is attributed to the higher diffusion coefficient of Fe(acac)3 from organic phase to aqueous phase. This work provided a novel strategy to fabricate metal-organic composite membrane with sub-2 nm pores; meanwhile, the new-prepared membrane shows a high Na2SO4 rejection of 97.3% with the water permeance of 8.6 L m−2 h−1 bar−1, and a high VB12 rejection of 97.6%, indicating an excellent ion/molecule separation performance.

Large orbital polarization in nickelate-cuprate heterostructures by dimensional control of oxygen coordination

Artificial heterostructures composed of dissimilar transition metal oxides provide unprecedented opportunities to create remarkable physical phenomena. Here, we report a means to deliberately control the orbital polarization in LaNiO3 (LNO) through interfacing with SrCuO2 (SCO), which has an infinite-layer structure for CuO2. Dimensional control of SCO results in a planar-type (P–SCO) to chain-type (C–SCO) structure transition depending on the SCO thickness. This transition is exploited to induce either a NiO5 pyramidal or a NiO6 octahedral structure at the SCO/LNO interface. Consequently, a large change in the Ni d orbital occupation up to ~30% is achieved in P–SCO/LNO superlattices, whereas the Ni eg orbital splitting is negligible in C–SCO/LNO superlattices. The engineered oxygen coordination triggers a metal-to-insulator transition in SCO/LNO superlattices. Our results demonstrate that interfacial oxygen coordination engineering provides an effective means to manipulate the orbital configuration and associated physical properties, paving a pathway towards the advancement of oxide electronics.

In vivo two-photon imaging/excited photothermal therapy strategy of a silver-nanohybrid.

A multi-functional nanohybrid (PyAnOH-Ag) with both a two-photon photothermal therapy (TP-PTT) effect and two-photon excited fluorescence (TPEF) imaging performance has been fabricated based on interfacial coordination interactions. The hybrid possesses a high two-photon absorption cross section (δTPA, 4638 GM) and detectable TPEF signals, which leads to excellent two-photon photothermal conversion. Upon irradiation at 840 nm, the temperature of the PyAnOH-Ag-PBS suspension reaches 42 °C in just 4 min, which results in 80% photothermal toxicity on HepG2 cells. The detectable TPEF signals can be used to monitor the cell ablation procedure. Moreover, PyAnOH-Ag exhibits a good phototherapeutic effect on tumor tissue of H22-modelled mice with almost 100% tumor growth inhibition under 840 nm irradiation for 10 min, which is superior to many reported photothermal agents. This strategy of TPEF guided TP-PTT agents can be potentially applied in a variety of therapeutic agents with monitoring ability.