A novel CdTe/Eu-MOF photoanode for application in quantum dot-sensitized solar cell to improve power conversion efficiency

Preparation of a CeO2 ball-core structure and its application in quantum dot sensitized solar cells

A pomegranate-like nanosphere structure of CeO₂ was prepared by a simple one-step hydrothermal method, and the novel CeO₂ structure was printed on a TiO₂ film to form a scattering layer, which constituted the composite structure of a photoanode in a thin film optoelectronic device. Then ZnCuInSe quantum dots, a ZnS passivation layer and a CuS counter electrode were prepared, and these parts were assembled into quantum dot-sensitized solar cells. By changing the thickness of the scattering layer film in the photoanode, the quantum dots were adsorbed on TiO₂ more effectively. By using the special ball-core structure, light was scattered so that the photoanode used the light many times, which effectively increased the efficiency of photoelectron production. After electrochemical testing of the device, it was found that the photoconversion efficiencies of the TiO₂ transparent layer and the CeO₂ scattering layer composite photoanode were greater than that of a single TiO₂ photoanode without a scattering layer. The results showed that when the thickness of the scattered layer was 10 ± 1 μm, the highest photoelectric conversion efficiency (PCE) was obtained, which was 20% higher than that seen with TiO₂ alone.

Recent Advances and Challenges in Light Conversion Phosphor Materials for Third-Generation Quantum-Dot-Sensitized Photovoltaics

Photovoltaic (PV) technologies have received tremendous attention for producing clean and renewable energy from the Sun. Third-generation quantum-dot-sensitized solar cells (QDSCs) present promising alternatives to conventional silicon solar cells due to their unique properties such as simplicity in fabrication, lower processing temperature, high flexibility, semitransparent nature, and a theoretical conversion efficiency of up to 44%. However, the light-harvesting QD materials used in these SCs allow for the absorption of a small portion (from 300 to 800 nm) of the solar spectrum due to their narrow band gap. The nonabsorption of UV and near-infrared (NIR) light limits the power conversion efficiency (PCE) of these SCs. Hence, a PV technique that efficiently uses the entire solar spectrum becomes essential. The incorporation of light conversion phosphor materials (LCs) in QDSCs is a promising technology to absorb the whole part of the solar spectrum and enhance the PCE of these SCs. This review presents an overview of the advantages and limitations of QDSCs, different types of lanthanide-based light conversion phosphor materials, their synthesis and light conversion mechanism, and their influence on QDSCs.

Synthesis and Characterization of Zn-Organic Frameworks Containing Chitosan as a Low-Cost Inhibitor for Sulfuric-Acid-Induced Steel Corrosion: Practical and Computational Exploration

In this work, a Zn-benzenetricarboxylic acid (Zn@H3BTC) organic framework coated with a dispersed layer of chitosan (CH/Zn@H3BTC) was synthesized using a solvothermal approach. The synthesized CH/Zn@H3BTC was characterized by Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscope (FESEM), thermal gravimetric analysis (TGA), and Brunauer, Emmett, and Teller (BET) surface area. The microscopic observation and the analysis of the BET surface area of CH/Zn@H3BTC nanocomposites indicated that chitosan plays an important role in controlling the surface morphology and surface properties of the Zn@H3BTC. The obtained findings showed that the surface area and particle size diameter were in the range of 80 m2 g-1 and 800 nm, respectively. The corrosion protection characteristics of the CH/Zn@H3BTC composite in comparison to pristine chitosan on duplex steel in 2.0 M H2SO4 medium determined by electrochemical (E vs. time, PDP, and EIS) approaches exhibited that the entire charge transfer resistance of the chitosan- and CH/Zn@H3BTC-composite-protected films on the duplex steel substrate was comparatively large, at 252.4 and 364.8 Ω cm2 with protection capacities of 94.1% and 97.8%, respectively, in comparison to the unprotected metal surface (Rp = 20.6 Ω cm2), indicating the films efficiently protected the metal from corrosion. After dipping the uninhabited and protected systems, the surface topographies of the duplex steel were inspected by FESEM. We found the adsorption of the CH/Zn@H3BTC composite on the metal interface obeys the model of the Langmuir isotherm. The CH/Zn@H3BTC composite revealed outstanding adsorption on the metal interface as established by MD simulations and DFT calculations. Consequently, we found that the designed CH/Zn@H3BTC composite shows potential as an applicant inhibitor for steel protection.

Near-infrared photoactive Yb-MOF functionalized with a large conjugate ionic liquid: synthesis and application for photoelectrochemical immunosensing of carcinoma embryonic antigen

A novel near-infrared (NIR)-excited photoelectrochemical (PEC) immunosensor based on an ionic liquid functionalized metal organic framework (Yb-MOF) and gold nanoparticles (Au-NPs) was designed for the high-performance determination of carcinoembryonic antigen (CEA). The Yb-MOF was synthesized from the coordination of the Yb3+ metal ion with the 1,1'-(1,5-dihydropyrene-2,7-diyl)bis(3-(4-carboxybenzyl)-1H-imidazol-3-ium) bromide [DDPDBCBIm(Br)2] ionic liquid by a hydrothermal method. To improve the photoelectric conversion efficiency of the Yb-MOF in the NIR region, the surface of the Yb-MOF was integrated with gold nanoparticles (AuNPs) to fabricate a Yb-MOF@AuNP nanocomposite through an in situ reduction of chloroauric acid with sodium borohydride. The NIR photoelectrochemical response of the Yb-MOF@AuNPs at 808 nm was enhanced 4-fold over the pristine Yb-MOF. Subsequently, a photoelectrochemical platform based on the Yb-MOF@AuNPs was constructed for loading the CEA antibody (anti-CEA). After cross-linking with glutaraldehyde followed by blocking with bovine serum albumin, a photoelectrochemical sensor for assaying CEA was fabricated. Upon specifically interacting with CEA, CEA can block the photogenerated electron-hole pair transfer and the mass transfer of ascorbic acid to the sensing interface, thus leading to a decrease in photocurrent response. The photocurrent variation can be used for determining CEA quantitatively. After optimizing the experimental conditions, the photocurrent variations before and after incubation with CEA were linearly correlated with the CEA concentration over the range of 0.005-15 ng mL-1. The detection limit of CEA was calculated to be 0.25 pg mL-1 (S/N = 3). The immunosensor was employed for the measurement of free CEA in clinical serum samples, and the results were very consistent with the values obtained by clinical tests. The NIR PEC immunosensor also demonstrated excellent accuracy and recovery, which corroborates its potential as a practical technique in clinical diagnosis.

Application of Metal-Organic Frameworks and Covalent Organic Frameworks as (Photo)Active Material in Hybrid Photovoltaic Technologies

Metal-organic frameworks (MOFs) and covalent organic frameworks (COFs) are two innovative classes of porous coordination polymers. MOFs are three-dimensional materials made up of secondary building blocks comprised of metal ions/clusters and organic ligands whereas COFs are 2D or 3D highly porous organic solids made up by light elements (i.e., H, B, C, N, O). Both MOFs and COFs, being highly conjugated scaffolds, are very promising as photoactive materials for applications in photocatalysis and artificial photosynthesis because of their tunable electronic properties, high surface area, remarkable light and thermal stability, easy and relative low-cost synthesis, and structural versatility. These properties make them perfectly suitable for photovoltaic application: throughout this review, we summarize recent advances in the employment of both MOFs and COFs in emerging photovoltaics, namely dye-sensitized solar cells (DSSCs) organic photovoltaic (OPV) and perovskite solar cells (PSCs). MOFs are successfully implemented in DSSCs as photoanodic material or solid-state sensitizers and in PSCs mainly as hole or electron transporting materials. An innovative paradigm, in which the porous conductive polymer acts as standing-alone sensitized photoanode, is exploited too. Conversely, COFs are mostly implemented as photoactive material or as hole transporting material in PSCs.

Metal-Organic Framework Materials for Perovskite Solar Cells

Metal-organic frameworks (MOFs) and MOF-derived materials have been used for several applications, such as hydrogen storage and separation, catalysis, and drug delivery, owing to them having a significantly large surface area and open pore structure. In recent years, MOFs have also been applied to thin-film solar cells, and attractive results have been obtained. In perovskite solar cells (PSCs), the MOF materials are used in the form of an additive for electron and hole transport layers, interlayer, and hybrid perovskite/MOF. MOFs have the potential to be used as a material for obtaining PSCs with high efficiency and stability. In this study, we briefly explain the synthesis of MOFs and the performance of organic and dye-sensitized solar cells with MOFs. Furthermore, we provide a detailed overview on the performance of the most recently reported PSCs using MOFs.

Current status and future prospects of metal–organic frameworks at the interface of dye-sensitized solar cells

In this Frontier Article recent progresses and challenges at the interface of metal–organic frameworks and dye-sensitized solar cells are highlighted and discussed.

Chitosan modified metal–organic frameworks as a promising carrier for oral drug delivery

The drug delivery system of CS-MOF@5-FU was developed to achieve oral administration of 5-FU.

Synthesis of a CdS-decorated Eu-MOF nanocomposite for the construction of a self-powered photoelectrochemical aptasensor

A composite of CdS nanoparticles and a europium metal organic framework (Eu-MOF) (CdS/Eu-MOF) was synthesized. The unique properties of MOFs help to improve the photoelectrochemical (PEC) properties of CdS by reducing charge carrier recombination and utilizing a broader spectrum for light harvesting. Under visible light illumination, the photocurrent of the CdS/Eu-MOF composite modified electrode was about 2.5-fold higher than that of the CdS modified electrode. When an ampicillin (AMP)-binding aptamer was immobilized on the CdS/Eu-MOF modified electrode as a recognition element, a self-powered PEC aptasensor exhibiting a specific photocurrent response to AMP was constructed. Several experimental conditions such as the ratio of CdS to MOF, the coating amount of the CdS/Eu-MOF suspension and the concentration of the aptamer were studied. Under optimum conditions, the photocurrent of the developed sensor was linearly related to the logarithm AMP concentration in the range of 1 × 10-10 to 2 × 10-7 M, with a detection limit (3S/N) of 9.3 × 10-11 M. Moreover, this sensor exhibited excellent selectivity, good repeatability and desirable stability. It was successfully applied to the detection of AMP in lake water and milk samples.

Application of metal-organic framework as redox probe in an electrochemical aptasensor for sensitive detection of MUC1

In this work, an electrochemical aptasensor was developed for sensitive detection of MUC1 based on metal-organic framework-reduced graphene oxide nanocomposite (Cu-MOF-RGO). Cu- MOF-RGO appeared to be suitable as a platform for immobilization of MUC1 aptamer, and also as an electrochemical probe, which exhibited well-defined peaks with good stability and reproducibility. Cu-MOF-graphene oxide (Cu-MOF-GO) nanocomposite was prepared and cast on the electrode surface, then in order to increase the conductivity of the electrode, GO was electrochemically reduced to RGO. In the presence of MUC1, the peak current of Cu in the nanocomposite decreased, which could be explained based on the formation of MUC1-aptamer complexes on the electrode, and consequence blocking the electron transfer of Cu at the electrode surface. Under optimum experimental conditions, a linear calibration curve was obtained by differential pulse voltammetry in the concentration range of 0.1 pM-10 nM (25 pg mL^-1 - 2500 ng mL^-1) with a limit of detection (LOD) of 0.033 pM (7.5 pg mL^-1) of MUC1. The proposed aptasensor offers acceptable selectivity, stability, and reproducibility in the determination of MUC1 spiked to human blood serum samples.

Mixed-Ligand-Architected 2D Co(II)-MOF Expressing a Novel Topology for an Efficient Photoanode for Water Oxidation Using Visible Light

The structural diversity of Co(II) metal centers is known to influence their physicochemical properties. A novel two-dimensional (2D) Co(II)-MOF {[Co₅(HL)₄(dpp)₂(H₂O)₂(μ-OH)₂]·21H₂O} n has been designed and synthesized by adopting a mixed-ligand strategy, using 1,3-di(4-pyridyl)propane (dpp) colinker with a flexible spacer H₃L (H₃L: 5-(2 carboxybenzyloxy)isophthalic acid). Co(II)-MOF features a 2D network, which is further interpenetrated among the equivalent sets and therefore results in a 3D supramolecular network. Topologically, the entire network can be viewed as a (3,4,8)-connected three-nodal net with the extended point symbol of {4.5.7}4{4¹².5².7¹⁰.9⁴}{5².8.9².10}2, duly assigned to the novel topological type smm2. The functional utility of Co(II)-MOF is demonstrated by employing it toward oxygen evolution reaction (OER) in a photoelectrochemical cell, exhibiting appreciable photocurrents of up to 5.89 mA/cm² when used as an anode in a photoelectrochemical cell, while also displaying encouraging electrocatalytic currents of 9.32 mA/cm² (at 2.01 V vs RHE) for the OER. Moreover, detailed electrochemical impedance spectroscopy studies confirm enhanced charge-transfer kinetics and improved conductivity under illumination with minimal effect of interfacial phenomena. This work provides a reference for the expanding field of research into applications of MOF materials and establishes MOF materials as favorable candidates for sustainable and efficient design of electrodes for water splitting.

Metal–Organic Framework Hybrid Materials and Their Applications

The inherent porous nature and facile tunability of metal–organic frameworks (MOFs) make them ideal candidates for use in multiple fields. MOF hybrid materials are derived from existing MOFs hybridized with other materials or small molecules using a variety of techniques. This led to superior performance of the new materials by combining the advantages of MOF components and others. In this review, we discuss several hybridization methods for the preparation of various MOF hybrids with representative examples from the literature. These methods include covalent modifications, noncovalent modifications, and using MOFs as templates or precursors. We also review the applications of the MOF hybrids in the fields of catalysis, drug delivery, gas storage and separation, energy storage, sensing, and others.

MOF-Bacteriophage Biosensor for Highly Sensitive and Specific Detection of Staphylococcus aureus

To produce a sensitive and specific biosensor for Staphylococcus aureus, bacteriophages have been interfaced with a water-dispersible and environmentally stable metal-organic framework (MOF), NH₂-MIL-53(Fe). The conjugation of the MOF with bacteriophages has been achieved through the use of glutaraldehyde as cross-linker. Highly sensitive detection of S. aureus in both synthetic and real samples was realized by the proposed MOF-bacteriophage biosensor based on the photoluminescence quenching phenomena: limit of detection (31 CFU/mL) and range of detection (40 to 4 × 10⁸ CFU/mL). This is the first report exploiting the use of an MOF-bacteriophage complex for the biosensing of S. aureus. The results of our study highlight that the proposed biosensor is more sensitive than most of the previous methods while exhibiting some advanced features like specificity, regenerability, extended range of linear detection, and stability for long-term storage (even at room temperature).