Trilayer Metal-Organic Frameworks as Multifunctional Electrocatalysts for Energy Conversion and Storage Applications.

The need for enhanced energy storage and improved catalysts has led researchers to explore advanced functional materials for sustainable energy production and storage. Herein, we demonstrate a reductive electrosynthesis approach to prepare a layer-by-layer (LbL) assembled trimetallic Fe-Co-Ni metal-organic framework (MOF) in which the metal cations within each layer or at the interface of the two layers are linked to one another by bridging 2-amino-1,4-benzenedicarboxylic acid linkers. Tailoring catalytically active sites in an LbL fashion affords a highly porous material that exhibits excellent trifunctional electrocatalytic activities toward the hydrogen evolution reaction (ηj=10 = 116 mV), oxygen evolution reaction (ηj=10 = 254 mV), as well as oxygen reduction reaction (half-wave potential = 0.75 V vs reference hydrogen electrode) in alkaline solutions. The dispersion-corrected density functional theory calculations suggest that the prominent catalytic activity of the LbL MOF toward the HER, OER, and ORR is due to the initial negative adsorption energy of water on the metal nodes and the elongated O-H bond length of the H2O molecule. The Fe-Co-Ni MOF-based Zn-air battery exhibits a remarkable energy storage performance and excellent cycling stability of over 700 cycles that outperform the commercial noble metal benchmarks. When assembled in an asymmetric device configuration, the activated carbon||Fe-Co-Ni MOF supercapacitor provides a superb specific energy and a power of up to 56.2 W h kg-1 and 42.2 kW kg-1, respectively. This work offers not only a novel approach to prepare an LbL assembled multimetallic MOF but also provides a benchmark for a multifunctional electrocatalyst for water splitting and Zn-air batteries.

Recent Advances in Carbon Anodes for Sodium-Ion Batteries.

Sodium-ion batteries (SIBs) have gained tremendous attention for large-scale energy storage applications due to the natural abundance, low cost, and even geographic distribution of sodium resources as well as a similar working mechanism to lithium-ion batteries (LIBs). One of the critical bottlenecks, however, is the design of high-performance and low-cost anode materials. Graphite anode that has dominated the market share of LIBs does not properly intercalate sodium ions. However, other carbonaceous materials are still considered as one of the most promising anode materials for SIBs in virtue of their high electronic conductivity, abundant active sites, hierarchical porosity, and excellent mechanical stability. In this review, we have tried to summarize the latest progresses made on the development of carbon-based negative electrodes (including hard carbons, soft carbons, and synthetic carbon allotropes) for SIBs. We also have provided a comprehensive understanding of their physical properties, the sodium ions storage mechanisms, and the improvement measures to cope with the current challenges. In addition, we have proposed future research directions for SIBs that will provide important insights into further development of carbon-based materials for SIBs.

Polyaniline-Lignin Interpenetrating Network for Supercapacitive Energy Storage.

Because of increasing interest in environmentally benign supercapacitors, earth-abundant biopolymers have found their way into value-added applications. Herein, a promising nanocomposite based on an interpenetrating network of polyaniline and sulfonated lignin (lignosulfonate, LS) is presented. On the basis of an appropriate regulation of the nucleation kinetics and growth behavior via applying a series of rationally designed potential pulse patterns, a uniform PANI-LS film is achieved. On the basis of the fast rate of H+ insertion-deinsertion kinetics, rather than the slow SO42- doping-dedoping process, the PANI-LS nanocomposite delivers specific capacitance of 1200 F g-1 at 1 A g-1 surpassing the best conducting polymer-lignin supercapacitors known. A symmetric PANI-LS||PANI-LS device delivers a high specific energy of 21.2 W h kg-1, an outstanding specific power of 26.0 kW kg-1, along with superb flexibility and excellent cycling stability. Thus, combining charge storage attributes of polyaniline and lignosulfonate enables a waste-to-wealth approach to improve the supercapacitive performance of polyaniline.

Exploration of Advanced Electrode Materials for Approaching High-Performance Nickel-Based Superbatteries.

The surging interest in high performance, low-cost, and safe energy storage devices has spurred tremendous research efforts in the development of advanced electrode active materials. Herein, the in situ growth of zinc-iron layered double hydroxide (Zn-Fe LDH) on graphene aerogel (GA) substrates through a facile, one-pot hydrothermal method is reported. The strong interaction and efficient electronic coupling between LDH and graphene substantially improve interfacial charge transport properties of the resulting nanocomposite and provide more available redox active sites for faradaic reactions. An LDH-GA||Ni(OH)2 device is also fabricated that results in greatly enhanced specific capacity (187 mAh g-1 at 0.1 A g-1 ), outstanding specific energy (147 Wh kg-1 ), excellent specific power (16.7 kW kg-1 ), along with 88% capacity retention after >10 000 cycles. This approach is further extended to Ni-MH and Ni-Cd batteries to demonstrate the feasibility of compositing with graphene for boosting the energy storage performance of other well-known Ni-based batteries. In contrast to conventional Ni-based batteries, the nearly flat voltage plateau followed by a sloping potential profile of the integrated supercapacitor-battery enables it to be discharged down to 0 V without being damaged. These findings provide new prospects for the design of high-performance and affordable superbatteries based on earth-abundant elements.

Towards establishing standard performance metrics for batteries, supercapacitors and beyond.

Over the past decade, electrochemical energy storage (EES) devices have greatly improved, as a wide variety of advanced electrode active materials and new device architectures have been developed. These new materials and devices should be evaluated against clear and rigorous metrics, primarily based on the evidence of real performances. A series of criteria are commonly used to characterize and report performance of EES systems in the literature. However, as advanced EES systems are becoming more and more sophisticated, the methodologies to reliably evaluate the performance of the electrode active materials and EES devices need to be refined to realize the true promise as well as the limitations of these fast-moving technologies, and target areas for further development. In the absence of a commonly accepted core group of metrics, inconsistencies may arise between the values attributed to the materials or devices and their real performances. Herein, we provide an overview of the energy storage devices from conventional capacitors to supercapacitors to hybrid systems and ultimately to batteries. The metrics for evaluation of energy storage systems are described, although the focus is kept on capacitive and hybrid energy storage systems. In addition, we discuss the challenges that still need to be addressed for establishing more sophisticated criteria for evaluating EES systems. We hope this effort will foster ongoing dialog and promote greater understanding of these metrics to develop an international protocol for accurate assessment of EES systems.

Engineering three-dimensional hybrid supercapacitors and microsupercapacitors for high-performance integrated energy storage.

Supercapacitors now play an important role in the progress of hybrid and electric vehicles, consumer electronics, and military and space applications. There is a growing demand in developing hybrid supercapacitor systems to overcome the energy density limitations of the current generation of carbon-based supercapacitors. Here, we demonstrate 3D high-performance hybrid supercapacitors and microsupercapacitors based on graphene and MnO2 by rationally designing the electrode microstructure and combining active materials with electrolytes that operate at high voltages. This results in hybrid electrodes with ultrahigh volumetric capacitance of over 1,100 F/cm(3). This corresponds to a specific capacitance of the constituent MnO2 of 1,145 F/g, which is close to the theoretical value of 1,380 F/g. The energy density of the full device varies between 22 and 42 Wh/l depending on the device configuration, which is superior to those of commercially available double-layer supercapacitors, pseudocapacitors, lithium-ion capacitors, and hybrid supercapacitors tested under the same conditions and is comparable to that of lead acid batteries. These hybrid supercapacitors use aqueous electrolytes and are assembled in air without the need for expensive "dry rooms" required for building today's supercapacitors. Furthermore, we demonstrate a simple technique for the fabrication of supercapacitor arrays for high-voltage applications. These arrays can be integrated with solar cells for efficient energy harvesting and storage systems.

Synthesis of NiMnO3/C nano-composite electrode materials for electrochemical capacitors.

Demand for high-performance energy storage materials has motivated research activities to develop nano-engineered composites that benefit from both high-rate and high-capacitance materials. Herein, NiMnO3 (NMO) nanoparticles have been synthesized through a facile co-precipitation method. As-prepared NMO samples are then employed for the synthesis of nano-composites with graphite (Gr) and reduced graphene oxide (RGO). Various samples, including pure NMO, NMO-graphite blend, as well as NMO/Gr and NMO/RGO nano-composites have been electrochemically investigated as active materials in supercapacitors. The NMO/RGO sample exhibited a high specific capacitance of 285 F g(-1) at a current density of 1 A g(-1), much higher than the other samples (237 F g(-1) for NMO/Gr, 170 F g(-1) for NMO-Gr and 70 F g(-1) for NMO). Moreover, the NMO/RGO nano-composite has shown excellent cycle stability with a 93.5% capacitance retention over 1000 cycles at 2 A g(-1) and still delivered around 87% of its initial capacitance after cycling for 4000 cycles. An NMO/RGO composite was assessed in practical applications by assembling NMO/RGO//NMO/RGO symmetric devices, exhibiting high specific energy (27.3 Wh kg(-1)), high specific power (7.5 kW kg(-1)), and good cycle stability over a broad working voltage of 1.5 V. All the obtained results demonstrate the promise of NMO/RGO nano-composite as a high-performance electrode material for supercapacitors.

Graphene-based materials for flexible supercapacitors.

The demand for flexible/wearable electronic devices that have aesthetic appeal and multi-functionality has stimulated the rapid development of flexible supercapacitors with enhanced electrochemical performance and mechanical flexibility. After a brief introduction to flexible supercapacitors, we summarize current progress made with graphene-based electrodes. Two recently proposed prototypes for flexible supercapacitors, known as micro-supercapacitors and fiber-type supercapacitors, are then discussed. We also present our perspective on the development of graphene-based electrodes for flexible supercapacitors.

Cadmium nanocluster as a safe nanocarrier: biodistribution in BALB/c mice and application to carry crocin to breast cancer cell lines.

Aim: Metal nanoclusters are emerging nanomaterials applicable for drug delivery. Here, the toxicity and oxidative stress induction of divalent cationic cadmium (Cd2+) was compared with a Cd in the form of nanocluster. Then, it was used for targeted drug delivery into breast cancer cell lines. Methods: Using a green chemistry route, a Cd nanocluster (Cd-NC) was synthesized based on bovine serum albumin. After characterization, its genotoxicity and oxidative stress induction were studied in both in vitro and in vivo. After that, it was conjugated with hyaluronic acid (HA). The efficiency of hyaloronized-Cd-CN (HA-Cd-NC) for loading and releasing crocin (Cro), an anticancer phytochemical, was studied. Finally, it was applied for cell death induction in a panel of breast cancer cell lines. Results: The comet assay results indicated that, unlike Cd2+ and potassium permanganate (KMnO4), no genotoxicity and oxidative stress was induced by Cd-NC in vitro. Then, the pharmacokinetics of this Cd-NC was studied in vivo. The data showed that Cd-NC has accumulated in the liver and excreted from the feces of mice. Unlike Cd2+, no toxicity and oxidative stress were induced by this Cd-NC in animal tissues. Then, the Cd-NC was targeted toward breast cancer cells by adding HA, a ligand for the CD44 cell surface receptor. After that, Cro was loaded on HA-Cd-NC and it was used for the treatment of a panel of human breast cancer cell lines with varying degrees of CD44. The half-maximal drug inhibitory concentration (IC50) of Cro was significantly decreased when it was loaded on HA-Cd-NC, especially in MDA-MB-468 with a higher degree of CD44 at the surface. These results indicate the higher toxicity of Cro toward breast cancers when carried out by HA-Cd-NC. Conclusions: The Cd-NC was completely safe and is a promising candidate for delivering anticancer drugs/phytochemicals into the targeted breast tumors.

Tailoring Metal-Organic Frameworks and Derived Materials for High-Performance Zinc-Air and Alkaline Batteries.

Developing multifunctional materials from earth-abundant elements is urgently needed to satisfy the demand for sustainable energy. Herein, we demonstrate a facile approach for the preparation of a metal-organic framework (MOF)-derived Fe2O3/C, composited with N-doped reduced graphene oxide (MO-rGO). MO-rGO exhibits excellent bifunctional electrocatalytic activities toward the oxygen evolution reaction (ηj=10 = 273 mV) and the oxygen reduction reaction (half-wave potential = 0.77 V vs reversible hydrogen electrode) with a low ΔEOER-ORR of 0.88 V in alkaline solutions. A Zn-air battery based on the MO-rGO cathode displays a high specific energy of over 903 W h kgZn-1 (∼290 mW h cm-2), an excellent power density of 148 mW cm-2, and an open-circuit voltage of 1.430 V, outperforming the benchmark Pt/C + RuO2 catalyst. We also hydrothermally synthesized a Ni-MOF that was partially transformed into a Ni-Co-layered double hydroxide (MOF-LDH). A MO-rGO||MOF-LDH alkaline battery exhibits a specific energy of 42.6 W h kgtotal mass-1 (106.5 µW h cm-2) and an outstanding specific power of 9.8 kW kgtotal mass-1 (24.5 mW cm-2). This work demonstrates the potential of MOFs and MOF-derived compounds for designing innovative multifunctional materials for catalysis, electrochemical energy storage, and beyond.

Phase-Dependent Energy Storage Performance of the NixSey Polymorphs for Supercapacitor-Battery Hybrid Devices.

Transition-metal chalcogenides have emerged as a promising class of materials for energy storage applications due to their earth abundance, high theoretical capacity, and high electrical conductivity. Herein, we introduce a facile and one-pot electrodeposition method to prepare high-performance nickel selenide NixSey (0.5 ≤ x/y ≤ 1.5) nanostructures (specific capacity = 180.3 mA h g-1 at 1 A g-1). The as-synthesized nickel selenide (NS) nanostructure is however converted to other polymorphs of nickel selenide including orthorhombic NiSe2, trigonal Ni3Se2, hexagonal NiSe, and orthorhombic Ni6Se5 over cycling. Interestingly, NiSe2 and Ni3Se2 polymorphs that display a more metallic character and superior energy storage performance are the predominant phases after a few hundred cycles. We fabricated a hybrid device using activated carbon (AC) as a supercapacitor-type negative electrode and NS as a high-rate battery-type positive electrode (AC||NS). This hybrid device provides a high specific energy of 71 W h kg-1, an excellent specific power of up to 31 400 W kg-1, and exceptional cycling stability (80% retention of the initial capacity after 20 000 cycles). The higher energy storage performance of the device is a result of the development of high-performance NiSe2 and Ni3Se2 polymorphs. Moreover, the reduction of the critical dimension of the NS particles to the nanoscale partially induces an extrinsic pseudocapacitive behavior that improves the rate capability and durability of the device. We also explored the origin of the superior energy storage performance of the NS polymorphs using density functional theory calculations in terms of the computed density of states around the Fermi level, electrical conductivity, and quantum capacitance that follows the trend NiSe2 > Ni3Se2 > NiSe > Ni6Se5. The present study thus provides an appealing approach for tailoring the phase composition of NS as an alternative to the commonly used templated synthesis methods.

Nile Blue Functionalized Graphene Aerogel as a Pseudocapacitive Negative Electrode Material across the Full pH Range.

The pursuit of new negative electrode materials for redox supercapacitors with a high capacitance, boosted energy, and high rate capability is still a tremendous challenge. Herein, we report a Nile Blue conjugated graphene aerogel (NB-GA) as a negative electrode material with excellent pseudocapacitive performance (with specific capacitance of up to 483 F g-1 at 1 A g-1) in all acidic, neutral, and alkaline aqueous electrolytes. The contribution from capacitive charge storage represents 93.4% of the total charge, surpassing the best pseudocapacitors known. To assess the feasibility of NB-GA as a negative electrode material across the full pH range, we fabricated three devices, namely, a symmetric NB-GA||NB-GA device in an acidic (1.0 M H2SO4) electrolyte, an NB-GA||MnO2 device in a pH-neutral (1.0 M Na2SO4) electrolyte, and an NB-GA||LDH (LDH = Ni-Co-Fe layered double hydroxide) device in an alkaline (1.0 M KOH) electrolyte. The NB-GA||NB-GA device exhibits a maximum specific energy of 22.1 Wh kg-1 and a specific power of up to 8.1 kW kg-1; the NB-GA||MnO2 device displays a maximum specific energy of 55.5 Wh kg-1 and a specific power of up to 14.9 kW kg-1, and the NB-GA||LDH device shows a maximum specific energy of 108.5 Wh kg-1 and a specific power of up to 25.1 kW kg-1. All the devices maintain excellent stability over 5000 charge-discharge cycles. The outstanding pseudocapacitive performances of the NB-GA nanocomposites render them a highly promising negative electrode material across the entire pH range.

Saffron carotenoids (crocin and crocetin) binding to human serum albumin as investigated by different spectroscopic methods and molecular docking.

Therapeutic effects of saffron ingredients were studied in some diseases. The pharmacokinetics and pharmacodynamics of these ingredients were also studied, but their transport mechanism is not clearly known. Serum albumin has been known as the most important transporter of many drugs in the body that affects their disposition, transportation, and bioavailability. Here, we investigated the interaction of crocin (Cro) with HSA, for the first time, and compared with the crocetin (Crt)-HSA interaction. UV and fluorescence spectroscopy, circular dichroism (CD), and molecular docking was applied to investigate the possibility and mechanism of binding of HSA with these natural carotenoids. The gradually addition of Cro increased HSA absorbency at 278 nm, while Crt decreased it. Both of these changes induced HSA unfolding that was confirmed by the decreased α-helix content, as determined by the CD. Both carotenoids quenched HSA fluorescence emission, but with different mechanisms. The Stern-Volmer plots indicated a dynamic quenching of intrinsic emission of HSA due to Cro addition, while Crt quenching followed both static and dynamic quenching mechanisms. Docking results indicated binding of Cro/Crt in sub-domain IIA, Sudlow site I of HSA, which accompanied with the hydrogen bonding of Cro/Crt with Tyr138. The interaction of these ligands (Cro/Crt) caused HSA unfolding and affects the hydrophobic environment of Trp241, which result in the quenching of Trp fluorescence. The UV spectroscopy and fluorescence quenching data indicated the differences in the mechanisms of interaction of Cro/Crt with HSA, which is due to the differences in the structure and hydrophobicity of these ligands.

Preparation of a new nanobiosensor for the determination of some biogenic polyamines and investigation of their interaction with DNA.

Biogenic polyamines are small organic polycations involving in a variety of biological processes. They form high affinity complexes with DNA. Here, we have followed two different novel approaches, either fabrication of an electrochemical nanobiosensor for determination of three of the most important biogenic polyamines; spermine (SPM), spermidine (SPD) and putrescine (PUT), or electrochemical investigation of their interaction with DNA. Strong binding of polyamines to DNA makes the DNA a suitable recognition element for construction of a sensitive biosensor. The fabricated biosensor responded to SPM, SPD and PUT over an extended dynamic range of 0.04-100 µM, 0.01-24 µM, and 0.08-100 µM respectively, with low detection limits of a few nM. We also studied the interaction of polyamines with three different DNA sequences with base composition of 100% AT, 80% AT and 100% GC in the presence of [Ru(NH3)6]3(+) as a redox probe. The highest kb values were obtained in the interaction of polyamines with 80% AT (mixed) DNA sequence. The kb values were 5.24 × 10(5), 4.17 × 10(5) and 1.46 × 10(5)M(-1) for SPM, SPD and PUT, respectively, which correlated well with their increasing number of amino groups. In addition, competition study showed the impotence of SPD to replace with histone H1 in histone H1-DNA complex, which indicates the more potent interaction of histone H1 with DNA. In this proof-of-principle study, we have proposed an approach for simple, cost-effective, miniaturizable, and direct-readout detection of polyamines, as well as the understanding of the modes of interaction between polyamines and DNA.

Electrochemical aptamer/antibody based sandwich immunosensor for the detection of EGFR, a cancer biomarker, using gold nanoparticles as a signaling probe.

Detection of epidermal growth factor receptor (EGFR) in biological fluids is of paramount importance, since it has significant application in cancer diagnosis, drug development, and therapy monitoring. EGFR is a cancer biomarker, and its overexpression is associated with the development of some types of cancer. Herein, we report on the development of a sensitive and selective electrochemical aptamer/antibody (Apt/Ab) sandwich immunosensor for detection of EGFR. In this study, a biotinylated anti-human EGFR Apt was immobilized on streptavidin-coated magnetic beads (MB) and served as a capture probe. A polyclonal anti-human EGFR Ab was conjugated to citrate-coated gold nanoparticles (AuNPs) and used as a signaling probe. In the presence of EGFR, an Apt-EGFR-Ab sandwich was formed on the MB surface. The extent of the complexation was evaluated by differential pulse voltammetry of AuNPs after their dissolution in HCl. Under optimal conditions, the dynamic concentration range of the immunosensor for EGFR spanned from 1 to 40 ng/mL, with a low detection limit of 50 pg/mL, and RSD percent of less than 4.2%. The proposed approach takes advantage of sandwich assay for high specificity, MBs for fast separation, and electrochemical method for cost-effective and sensitive detection. In this proof-of-principle study, we demonstrate the potential clinical efficacy of the immunosensor for monitoring of chemotherapy effectiveness in breast cancer samples.

Designing 3D highly ordered nanoporous CuO electrodes for high-performance asymmetric supercapacitors.

The increasing demand for energy has triggered tremendous research efforts for the development of lightweight and durable energy storage devices. Herein, we report a simple, yet effective, strategy for high-performance supercapacitors by building three-dimensional pseudocapacitive CuO frameworks with highly ordered and interconnected bimodal nanopores, nanosized walls (∼4 nm) and large specific surface area of 149 m(2) g(-1). This interesting electrode structure plays a key role in providing facilitated ion transport, short ion and electron diffusion pathways and more active sites for electrochemical reactions. This electrode demonstrates excellent electrochemical performance with a specific capacitance of 431 F g(-1) (1.51 F cm(-2)) at 3.5 mA cm(-2) and retains over 70% of this capacitance when operated at an ultrafast rate of 70 mA cm(-2). When this highly ordered CuO electrode is assembled in an asymmetric cell with an activated carbon electrode, the as-fabricated device demonstrates remarkable performance with an energy density of 19.7 W h kg(-1), power density of 7 kW kg(-1), and excellent cycle life. This work presents a new platform for high-performance asymmetric supercapacitors for the next generation of portable electronics and electric vehicles.

Facile synthesis of nanostructured CuCo2O4 as a novel electrode material for high-rate supercapacitors.

CuCo2O4 nanostructures were synthesized through a facile solution combustion method. Electrochemical investigations demonstrate a novel electrode material for supercapacitors with remarkable performance including high-rate capability, high-power density (22.11 kW kg(-1)) and desirable cycling stability at different current densities.