2-aminoterephthalic Acid Research Articles

Self-Adaptive Electronic Structure of Amphoteric Conjugated Ligand-Modified 3 d Metal-C3 N4 Smart Electrocatalyst by pH Self-Response Realizing Electrocatalytic Self-Adjustment.

Constructing pH-responsive smart material provides a new opportunity to address the problem that traditional electrocatalysts cannot achieve both alkaline oxygen evolution reaction (OER) and acidic hydrogen evolution reaction (HER) activities. In this study, amphoteric conjugated ligand (2-aminoterephthalic acid, BDC-NH2 )-modified 3d metal-anchored graphitic carbon nitride (3d metal-C3 N4 ) smart electrocatalysts are constructed, and self-adaptation of the electronic structure is realized by self-response to pH stimulation, which results in self-adjustment of alkaline OER and acidic HER. Specifically, the amino and carboxyl functional groups in BDC-NH2 undergo protonation and deprotonation respectively under different pH stimulation to adapt to environmental changes. Through DFT calculations, the increase or decrease of electron delocalization range brought by the self-response characteristic is found to lead to redistribution of the Bader charge around the modified active sites. The OER and HER activities are greatly promoted roughly 4.8 and 8.5 times over Co-C3 N4 after BDC-NH2 -induced self-adaptive processes under different environments, arising from the reduced energy barrier of O* to OOH* and ΔGH* . Impressively, the proposed BDC-NH2 -induced smart regulation strategy is applicable to a series of 3d metal anchors for C3 N4 , including Co, Ni and Fe, providing a general structural upgrading method for constructing smart electrocatalytic systems.

Fabrication of Ce-La-MOFs for defluoridation in aquatic systems: A kinetics, thermodynamics and mechanisms study

Ce-La-MOFs composites was fabricated via the hydrothermal method, and considered an adsorbent to remove fluoride from aqueous solutions, and its property for defluoridation was discussed in this work. This study evaluated the ideal preparation molar ratio, adsorption period, and initial fluoride concentration. The adsorption mechanism was deduced from the analysis of thermodynamics, kinetics models, and characterization (SEM, XRD, FTIR, EDS, BET, TG). Furthermore, the impact of co-existing ions on the removal efficiency and regeneration of adsorbents was investigated. The studies have shown that the optimum conditions for defluoridation by Ce-La-MOFs were pH close to 3.0, the molar ratio of lanthanum-nitrate, cerium-nitrate, and 2-aminoterephthalic acid (La: Ce: ATPA) equal to 3:1:2, the initial F− concentration of 10 mg L−1, and the adsorption time of 120 min. Under these conditions, the removal efficiency can exceed 90%. The interference experiments suggested that the adsorbent material was highly selective for F−. The existence of most additional ions has a limited influence on the adsorption capacity, with only a minimal amount having an inhibitory effect. Kinetic and thermodynamic studies unveiled that the adsorption procedure is well-fitted with the Langmuir and pseudo-second-order models, and reaches a maximum Langmuir adsorption capacity of 138.64 mg g−1 at 50 °C. The adsorption process involved the integration of ion exchange and electrostatic interaction mechanisms. The regeneration cycle experiments showed that the Ce-La-MOFs composites had a favorable regeneration ability. After four regenerations, the adsorption capacity still reached 36.25 mg g−1 with 73% removal efficiency at C0 = 10 mg L–1.

Enhanced efficiency and stability of carbon-based CsPbI2Br perovskite solar cells by introducing metal organic framework-derived Fe3O4@NC interfacial layer

Carbon-based CsPbI2Br perovskite solar cells (C–PSCs) have the advantages of low cost and stable performance, but the poor contact and energy mismatch between the perovskite layer and the carbon electrode lead to low power conversion efficiency (PCE). In this work, uniform spindle-shaped Fe3O4@NC composites have prepared by calcining Fe-based metal organic framework (Fe-MOF) NH2-MIL-88B(Fe), which has synthesized by solvothermal reaction using 2-aminoterephthalic acid as nitrogen and carbon sources. Using Fe3O4@NC composite and UV-Ozone treated Fe3O4@NC composite (Fe3O4@NC UVO) as the interfacial layer between the perovskite layer and the carbon electrode, the devices with a structure of FTO/SnO2/CsPbI2Br/interfacial layer/Carbon exhibit a maximum PCE of 12.25%, which is about 19.28% higher than that of the pristine device. The improved optoelectronic performance is mainly attributed to more matched energy level, denser interface contact, better carrier separation performance and better conductivity. After 19 days of storage at room temperature and ambient humidity, Fe3O4@NC UVO device has retained 87% of the initial PCE. This work provides a simple and effective strategy to improve the PCE and stability of carbon-based CsPbI2Br PSCs with Fe-MOFs-derived carbon materials.

Graphene Quantum Dots Incorporated UiO-66-NH 2 Based Fluorescent Nanocomposite for Highly Sensitive Detection of Quercetin

Quercetin can help with a variety of health problems. Most methods for measuring quercetin in biological fluids are characterized by low sensitivity and selectivity. The employment of metal–organic frameworks in sensor applications with carbon-based materials ushers in a new era. In this study, blue fluorescent graphene quantum dots (GQDs) embedded in a UiO-66-NH₂ metal–organic framework-based nanoprobe (GQDs@UiO-66-NH₂) were constructed for quercetin sensing. Initially, maize husk was used to produce blue fluorescent GQDs, whereas zirconium tetrachloride and 2-aminoterephthalic acid were used to synthesize extremely luminous UiO-66-NH₂. The addition of quercetin to GQDs@UiO-66-NH₂ leads to fluorescence dampening due to the adsorption potential of UiO-66-NH₂. The complexation of zirconium ions with the 3-OH and 4-C＝O functionalities of quercetin resulted in fluorescence quenching. The sensor has a linear concentration range and limit of detection for quercetin of 50–500 and 2.82 ng/mL, respectively. The nanoprobe’s usefulness for quercetin detection was then validated by a selectivity investigation in the presence of interfering chemicals. Furthermore, the percentage relative standard deviations were 4.20% and 2.90%, respectively, indicating great stability and repeatability. Fluorescence “Turn-On–Off” nanoprobes provide a simple, quick, sensitive, and selective method for monitoring quercetin.

Amine-functionalized mesoporous UiO-66 aerogel for CO2 adsorption

A mesoporous UiO-66-NH 2 aerogel is prepared via a straightforward sol-gel method without using any binders or mechanical pressures, in which the amine groups are directly introduced into the matrix by using 2-aminoterephthalic acid. The novel UiO-66-NH 2 aerogel also exhibits high specific surface area and mesopore-dominated structure, implying its highly potential use in CO 2 adsorption. For ulteriorly investigating the effect of amine loading on the CO 2 adsorption ability, a series of UiO-66-NH 2 aerogel with different amino content is fabricated by changing the ligand/metal molar ratio. When the molar ratio is 1.45, the CO 2 adsorption capacity reaches the optimum value of 2.13 mmol·g –1 at 25 °C and 0.1 MPa, which is 12.2% higher than that of pure UiO-66 aerogel. Additionally, UiO-66-NH 2 -1.45 aerogel also has noticeable CO 2 selectivity against N 2 and CH 4 as well as good regeneration stability. Such results imply that it has good application prospect in the field of CO 2 adsorption, and also contains the potential to be applied in catalysis, separation and other fields.

Preparation of Functionalized Zr-Based MOFs and MOFs/GO for Efficient Removal of 1,3-Butadiene from Cigarette Smoke.

Removal of 1,3-butadiene from cigarette smoke plays an important role in human health and environmental protection. Herein, a series of UiO-66 X% containing different ratios of the -NH2 group was synthesized via the solvothermal method by using terephthalic acid (H2BDC) and 2-aminoterephthalic acid (NH2-BDC) as ligands. Using GO as support, a series of UiO-66-NH2/GO Y% were prepared by controlling the ratio of UiO-66-NH2 and GO. The effects of -NH2 and GO contents on the structure and composition of MOFs were investigated. Finally, the different -NH2 contents of UiO-66 X% and the different GO contents of UiO-66-NH2/GO Y% were applied in 1,3-butadiene removal from cigarette smoke. The results showed that UiO-66 X% with the higher contents of -NH2 showed a higher rate of 1,3-butadiene removal, and UiO-66-NH2/GO Y% with the GO contents of 5% showed the highest removal rate of about 33.85%, which was 25.54% higher than that of activated carbon. In addition, the saturation capacity of the adsorbent materials for 1,3-butadiene was as high as 210.01-239.54 mg/g, showing great potential in reducing harmful components in cigarette smoke and environmental protection.

Ultra-fast and robust capture of fluoride by an amino terephthalic acid-facilitated lanthanum-based organic framework: insight into performance and mechanisms

A sorbent consisting of a lanthanum-loaded metal–organic framework, involving terephthalic acid (La@TPA) and amino terephthalic acid (La@ATPA) as organic linkers, was synthesized and evaluated for fluoride (F) removal from groundwater.

A water stable and highly fluorescent Zn(II) based metal-organic framework for fast detection of Hg2+, CrVI, and antibiotics.

The development of luminescent metal-organic frameworks for effective sensing and monitoring of environmental pollutants is of great significance for human health and environmental protection. In this work, a novel water-stable ZnII-based luminescent coordination polymer, namely {[Zn(BBDF)(ATP)]·2DMF·3H2O}n ((BBDF = 2,7-bis(1H-benzimidazol-1-yl)-9,9-dimethyl-9H-fluorene) and H2ATP = 2-aminoterephthalic acid), was designed and obtained using the mixed-ligand method. Structural analysis indicated that 1 presents a two-fold interpenetrated two-dimensional layer structure with one dimensional (1D) channels along the a axis. Intriguingly, the uncoordinated -NH2 group was danged onto the pore walls of 1. Remarkably, compound 1 shows good aqueous stability at different pH values of 3-13 and exhibits a fluorescence turn-off sensing behavior for Hg2+, Cr2O72-, CrO42-, and antibiotics (NFZ, NFT) in aqueous solution with high selectivity and sensitivity. The limits of detection (LOD) are 0.12 μM (Hg2+), 0.17 μM (Cr2O72-), 0.21 μM (CrO42-), 0.098 μM (NFZ), and 0.14 μM (NFT). The luminescence quenching mechanism analysis by experiment and theoretical calculation revealed that the competitive absorption and the photoinduced electron transfer process are largely responsible for the sensing of the two antibiotics, while the weak interaction contributes to the selective luminescence quenching for Hg2+.

An amine decorated MOF for direct capture of CO2 from ambient air.

A Zn(II)-based metal-organic framework (MOF) was synthesized by the self-assembly of the dicarboxylate ligand terephthalic acid (TPA), 2-aminoterephthalic acid (NH2-TPA) and N-donor auxiliary ligand 1,4-bis(4-pyridinylmethyl)piperazine (bpmp) using Zn(NO3)2·6H2O under hydrothermal conditions. {[Zn(TPA)0.5(NH2TPA)0.5(bpmp)]·DMF·7H2O}n (framework 1) has an sra topology with a BET surface area of 756 m2 g-1. The microporous nature of the framework is apparent from the significant CO2 adsorption capacities observed at various temperatures: 57 cc g-1 at 283 K, 46 cc g-1 at 293 K, 37 cc g-1 at 303 K, and 30 cc g-1 at 313 K. The considerable CO2 adsorption may be caused by the existence of free carboxylate and amine substituents that interact with the gas molecules and micropores. At room temperature, the activated MOF readily converts CO2 into cyclic carbonates when a suspension of the MOF is bubbled with ambient air and different epoxides under solvent-free conditions. The amine groups located within the pores of the MOF interact with CO2 molecules, enhancing their sorption and conversion to cyclic carbonates. However, due to interpenetration within framework 1, only smaller size epoxides can be accommodated and converted to cyclic carbonates in good yields. Additionally, the effectiveness of the catalyst is further confirmed by the positive outcomes obtained from the hot filtration control test. Grand canonical Monte Carlo (GCMC) molecular simulations were utilized to gain a better understanding of molecular interactions. GCMC results are in line with the experiments. The substantial adsorption of CO2 can be ascribed to the strong intermolecular interactions that occur between the amine groups within the framework and the CO2 molecules.

Metal organic framework derived NiO x nanoparticles for application as a hole transport layer in perovskite solar cells.

NiO x as a hole transport layer (HTL) has gained a lot of research interest in perovskite solar cells (PSCs), owing to its high optical transmittance, high power conversion efficiency, wide band-gap and ease of fabrication. In this work, four different nickel based-metal organic frameworks (MOFs) using 1,3,5-benzenetricarboxylic acid (BTC), terephthalic acid (TPA), 2-aminoterephthalic acid (ATPA), and 2,5-dihydroxyterephthalic acid (DHTPA) ligands respectively, have been employed as precursors to synthesize NiO x NPs. The employment of different ligands was found to result in NiO x NPs with different structural, optical and morphological properties. The impact of calcination temperatures of the MOFs was also studied and according to field emission scanning electron microscopy (FESEM), all MOF-derived NiO x NPs exhibited lower particle size at lower calcination temperature. Upon optimization, Ni-TPA MOF derived NiO x NPs calcined at 600 °C were identified to be the best for hole transport layer application. To explore the photovoltaic performance, these NiO x NPs have been fabricated as a thin film and its structural, optical and electrical characteristics were analyzed. According to the findings, the band energy gap (E g) of the fabricated thin film has been found to be 3.25 eV and the carrier concentration, hole mobility and resistivity were also measured to be 6.8 × 1014 cm-3; 4.7 × 1014 Ω cm and 2.0 cm2 V-1 s-1, respectively. Finally, a numerical simulation was conducted using SCAPS-1D incorporating the optical and electrical parameters from the thin film analysis. FTO/TiO2/CsPbBr3/NiO x /C has been utilized as the device configuration which recorded an efficiency of 13.9% with V oc of 1.89 V, J sc of 11.07 mA cm-2, and FF of 66.6%.

Bovine serum albumin-derived poly-l-glutamic acid-functionalized graphene quantum dots embedded UiO-66-NH2 MOFs as a fluorescence ‘On-Off-On’ magic gate for para-aminohippuric acid sensing

Evaluating para-aminohippuric acid (PAH) is emerging as a promising biomarker for the diagnostics of renal disease and other kidney-related illnesses. The present study aims to develop novel bovine serum albumin-derived poly-l-glutamic acid (PLGA) functionalized graphene quantum dots (PLGA-fGQDs) embedded in UiO-66-NH2 metal–organic frameworks (PLGA-fGQDs@UiO-66-NH2 MOFs) for monitoring of PAH. Initially, GQDs were achieved from bovine serum albumin (green precursor) via the single-step hydrothermal method. Here, functionalization with PLGA offers a tremendous increment in optical properties of GQDs. Then, highly luminescent UiO-66-NH2 MOFs were achieved using zirconium tetrachloride (ZrCl4) and 2-Aminoterephthalic acid (2-ATA) as a metal ion source and organic linker. Here, surface modification of GQDs with PLGA offered high quantum yield (QY), and responsiveness. Also, luminous UiO-66-NH2 MOFs afford a wide surface area for decorating of PLGA-fGQDs. The addition of gallium ions (Ga3+) into the probe solution resulted in fluorescence quenching (Turn-Off) whereas the incorporation of PAH resulted in fluorescence recovery (Turn-On). It is because of interaction with carboxylic functionality of PAH to Ga3+ followed by Ga-PAH complex formation. Herein, the wide concentration range and lowest limit of detection (LOD) were found to be 10 ng/mL to 900 ng/mL and 15.88 ng/mL, respectively. The specificity and real-time analysis in artificial urine validated the real-time adoption of a sensor for PAH detection. As well, it demonstrated good intraday/interday precision, stability analysis, and repeatability. In near future, the bundled illuminating PLGA-fGQDs@UiO-66-NH2 MOFs nanoprobe will be an attractive preference for tracking PAH in clinical specimens.

Synthesis of spindle-like amino-modified Zn/Fe bimetallic metal-organic frameworks as sorbents for dispersive solid-phase extraction and preconcentration of phytohormoes in vegetable samples

Amino-modified Zn/Fe bimetallic metal–organic frameworks (NH2-Zn/Fe-MIL-88) were synthesized using a one-step solvothermal method with FeCl3·6H2O and Zn(NO3)2·6H2O as metal salts and 2-aminoterephthalic acid as organic ligand. The morphology of NH2-Zn/Fe-MIL-88 can be regulated from octahedral-like to spindle-like with changing molar ratios of metal salts. Using NH2-Zn/Fe-MIL-88 as sorbent, a dispersive solid-phase extraction with putting sorbents into sample solution to extract targets was developed to preconcentrate phytohormones in vegetables. To study the extraction efficiency, a series of NH2-Zn/Fe-MIL-88s with varying molar ratios of metal salts were prepared. The results indicated that NH2-Zn/Fe-MIL-88(1) presented the highest extraction efficiency (82.6 %–98.1 %) to phytohormones among all prepared NH2-Zn/Fe-MIL-88(x). The limits of detection were calculated at 0.07–0.15 ng/mL. The adsorption isotherms and kinetic parameters of NH2-Zn/Fe-MIL-88 for phytohormones were conformed to Langmuir and pseudo-second-order models. The NH2-Zn/Fe-MIL-88 as sorbent combined with HPLC was applied to detect phytohormones in cucumber and tomato samples.

Ratiometric fluorescence detection of artemisinin based on photoluminescent Zn-MOF combined with hemin as catalyst

Artemisinin (ART) is a type of frontline drug to treat drug-resistant falciparum malaria. Simple, accurate and selective determination of ART is significant to monitor its clinical pharmaceutical efficacy. Herein, a new ratiometric fluorescence method has been designed for the determination of ART with Zn-MOF as fluorescence reference and hemin as catalyst, respectively. Zn-MOF possesses intrinsic fluorescence at 443 nm owing to 2-aminoterephthalic acid ligand. When o-phenylenediamine (OPD) is mixed with hemin, a weak fluorescent signal at 570 nm ascribed to oxidized product of OPD (oxOPD) is observed. In the presence of ART, hemin can catalyze ART to break its peroxide bridge and release a large number of reactive oxygen species, which effectively oxidize OPD into luminescent oxOPD. Therefore, the fluorescence at 570 nm is enhanced significantly while the fluorescence of Zn-MOF remains basically unchanged. Thus, a ratiometric fluorescence sensing platform has been constructed for the detection of ART. This method exhibits wider linear range (0.15 μM-150 μM) with detection limit of 50 nM. This novel and selective method has been used to detect ART in compound naphthoquinone phosphate tablets.

Bimetallic metal-organic frameworks for efficient visible-light-driven photocatalytic CO2 reduction and H2 generation

A series of robust octahedral bimetallic metal-organic frameworks, NH2-UiO-66(Zr/M), denoted as Zr/M-ATA, (where M is Fe, Co, or Cu) were prepared by solvothermal de novo reaction of 2-aminoterephthalic acid (denoted as H2ATA) and mixed metal salts using benzoic acid as a modulator. Photocatalytic studies revealed that Zr/Fe-ATA, Zr/Cu-ATA and Zr/Co-ATA containing double metals outperformed that of the monometallic Zr-ATA. Zr/Cu-ATA displayed excellent performance for visible-light-driven CO2 reduction with a formate formation rate of 122 μmol h−1 mmolMOF-1, which is among the highest performance of NH2-UiO-66 based MOFs. Furthermore, Zr/Cu-ATA is an efficient catalyst that can generate 12.8 mmol of H2 in 2 h under visible light irradiation. The light absorption band of Zr/Cu-ATA shifted to the near-IR region and the presence of Cu-oxo clusters significantly narrowed the bandgap from 2.95 eV (Zr-ATA) to 1.93 eV (Zr/Cu-ATA). Other photoelectrochemical studies further confirmed that the high catalytic performance of Zr/Cu-ATA can be ascribed to optimized bandgap, facile charge transfer and availability of large number of active sites.

Dual-strategy ECL biosensor based on rare Eu(II,III)-MOF as probe with antenna effect and sensitization for CYFRA 21-1 trace analysis

The choices of luminophore and coreactant accelerator are crucial in a constructed electrochemiluminescence (ECL) biosensor. In this work, a mixed-valence Eu-MOF (Sr(HCOO)2:Eu2+/Eu3+) as luminophore was synthesized based on the precursor of eight-coordinated Sr(HCOO)2 with P41212 space group and tetragonal crystal structure. The doped Eu3+ was in-situ reduced to Eu2+ by efficient reductant combined with ligand 2-aminoterephthalic acid and solvent thermal decomposition product dimethylamine, then the Eu2+ substitutively coordinated Sr(HCOO)2 due to the same ion radius and coordination environment between Eu2+ and Sr2+. Through UV–vis, fluorescence spectra and density functional theory (DFT) calculations, the specific luminescence mechanisms of Sr(HCOO)2:Eu2+/Eu3+ with the antenna effect and sensitization were verified. Thanks to the strongest catalysis of Ag to K2S2O8 and the high active sites, the AgCl rice roll-shaped nanoclusters (AgCl RRNCs) as coreactant accelerator encouraged the production of more SO4•−. Thereout, the constructed ECL biosensor showed high performance in trace detection of cytokeratin 19 fragment 21-1 (CYFRA 21-1) with low limit of detection (2.73 fg/mL) and wide detection range (5 fg/mL ∼ 100 ng/mL), which met the requirement for diagnosis and postoperative monitoring non-small-cell lung cancer in clinical treatment completely. These strategies also provided feasible ideas for efficient and stable other biosensors except ECL.

Alkaline phosphatase triggered ratiometric fluorescence immunoassay for detection of zearalenone

Inspired by the super-binding capacity of pyrophosphate (ppi) and copper ion (Cu2+), an alkaline phosphatase (ALP) triggered ratiometric fluorescence immunoassay was established for detection of zearalenone (ZEN). In the assay, ALP-antibody acted as a bridge connecting ZEN concentration and ratiometric fluorescence signals. Due to the super-binding ability of ppi and Cu2+, Cu2+ was immobilized to form ppi-Cu2+ complex and lost its oxidation activity. The presence of ALP can hydrolyze ppi and release Cu2+ which can oxidize OPD to DAP. Since the excitation wavelength of DAP coincided with the emission wavelength of 2-aminoterephthalic acid (PTA-NH2), a ratiometric fluorescence immunoassay can be developed. The limit of detection (LOD) was 0.014 ng/mL and the linear detection range was 3.51–17.78 ng/mL. The ratiometric fluorescence immunoassay had high accuracy and reliability (recoveries, 101.10–107.20%; coefficient of variation (CV), 2.15–7.65%). This method provided new ideas for efficient and accurate detection of ZEN.

A novel strategy for preparing metal-organic framework as a smart material for selective detection and efficient extraction of Pd(II) and Au(III) ions from E-wastes

The authors describe the synthesis of a novel nanocollector for detecting and extracting very low concentrations of Pd(II) and Au(III) ions with remarkable specificity and capability. A new strategy was used to prepare the nanocollector (azo-HNTA-MIL-101(Al) sensor). It depends on preparing the azo dye first, then using this azo dye as a linker for preparing the (Al) metal–organic framework (MOF). The new strategy guaranteed the functionalization of all the amino groups of the 2-aminoterephthalic acid. Successful preparation of the azo-HNTA-MIL-101(Al) sensor was corroborated by nitrogen adsorption–desorption isotherms, TEM, SEM, XRD, FT-IR, and XPS spectral analysis. In particular, the novel azo-HNTA-MIL-101(Al) sensor had a reasonable fluorescence due to the linker emission and outstanding sensing capability in detecting Pd(II) and Au(III) ions. With linear correlation values of 0.999 and 0.997, Beer's law was observed throughout a wide range of Pd(II) and Au(III) ions concentrations, respectively. A possible mechanism for fluorescence quenching was investigated. High sensitivity for extremely low concentrations up to 1.50 × 10−8 molL−1 (1.59 ppb for Pd(II)) was demonstrated by the innovative nanosensor. In addition, it works as an excellent sensor for the efficient detection and extraction of Pd(II) and Au(III) ions from aqueous media. The capacities of adsorption were 84.7 and 77.4 mg of Pd(II) and Au(III) per gram of the azo-HNTA-MIL-101(Al) sensor, respectively. The approach was employed with effectiveness in extracting and determining the Pd(II) and Au(III) ions in cell phone scrap motherboards.

Surface engineering of flower-like Co-N-C on carbon paper for improved overall water splitting

Designing efficient non-precious metal catalysts with superior activity and stability for water splitting has been the pursuit of researchers. The purpose of this work is to investigate the influence of 2-amino terephthalic acid on the surface engineering of flower-like Co-N-C for improved water splitting in an alkaline solution. The flower-like Co-N-C grown on carbon paper (Co-N-C/CP) were fabricated by a facile hydrothermal and subsequent annealing process. When the ratio of Co2+ and 2-amino terephthalic acid reaches 1:2 in the precursors, the resultant Co-N-C/CP exhibits the overpotential of 181 mV and 290 mV at 10 mV cm−2 for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. Furthermore, the Co-N-C/CP (1:2)||Co-N-C/CP(1:2) water splitting systems deliver a current density of 10 mA cm−2 at 1.56 V. After 1500 cycles, the required voltage for water splitting still maintains at 1.57 V. The outstanding electrocatalytic properties are attributed to the tuning electron structure on the surface of Co-N-C, which promotes the charge transfer and chemical mass transport during water splitting in an alkaline solution. This study provides a new opportunity to develop highly efficient cobalt-based catalysts for enhanced water splitting.

Optimization of MOF Synthesis

Synthesis optimization of the metal organic framework (MOF) UiO-66 has been carried out using 2-aminoterephthalic acid functional group, a zirconium salt and a modulator grafted into the UiO-66 framework. Reaction parameters such as the effects of temperature, reaction time, the nature of the zirconium salt and the ligand, the molar ratio between the zirconium salt and the ligand, the quantity of the modulator, the solvent and the effect of added water have been investigated. The synthesized MOFs have demonstrated excellent chemical and thermal stability, which ensured them to be used as carriers for drug delivery.

Solubility measurement and correlation of 2-aminoterephthalic acid in eight alcoholic solvents at different temperatures

This research experimentally measured the solubility of 2-aminoterephthalic acid in eight pure alcoholic solvents – methanol, ethanol, 1-propanol, 1-butanol, 2-propanol, 2-butanol, 2-methyl-2-propanol, and 3-methyl-1-butanol – from 303.15 to 338.15 K at normal pressure p = 0.1 MPa by the excess solid method. The measured solubility of 2-aminoterephthalic acid in these pure organic solvents was found to increase with the rise of temperature in the following order: 3-methyl-1-butanol (lowest solubility) < 1-butanol < 2-butanol < 1-propanol < 2-methyl-2-propanol ≈ 2-propanol < ethanol < methanol (highest solubility). The experimental solubility was correlated by the Van’t Hoff equation and the λh (Buchowski) equation. The apparent thermodynamic properties (Δ0Gsol, Δ0Hsol and Δ0Ssol) were calculated by the Van’t Hoff equation, from which it was concluded that the dissolution process is entropy-motivated and endothermal. In addition, the solvent effects on 2-aminoterephthalic acid solubility were studied by the KAT-LSER model, where the results showed that the polarizability accounts for 47.9 ± 4.2 % of the total solvent effect.A volcano-type relation between the dissolution entropy and enthalpy versus the solvent boiling point is reported, showing maximal values of 55.3 J mol−1 K−1 and 29.2 kJ mol−1, respectively, for intermediate molecular interactions of solute and solvent.