Superior Electrochemical Water Splitting and Energy-Storage Performances of In Situ Fabricated Charge-Separated Metal Organophosphonate Single Crystals.

The design and exploration of advanced materials as a durable multifunctional electrocatalyst toward sustainable energy generation and storage development is the most perdurable challenge in the domain of renewable energy research. Herein, a facile in situ solvothermal approach has been adopted to prepare a methylviologen-regulated crystalline metal phosphonate compound, [C12H14N2][Ni(C11H11N2)(H2hedp)2]2•6H2O (NIT1), (H4hedp = 1-hydroxyethane 1,1-diphosphonic acid) and well characterized by several techniques. The as-prepared NIT1 displays excellent bifunctional electrocatalytic activity with dynamic stability toward oxygen evolution reaction (η10 = 288 mV) and hydrogen evolution reaction (η10 = 228 mV) in alkaline (1.0 M KOH) and acidic mediums (0.5 M H2SO4), respectively. Such a low overpotential and Tafel slope (68 mV/dec for OER; 56 mV/dec for HER) along with long-term durability up to 20 h of NIT1 make it superior to benchmark the electrocatalyst and various nonprecious metal-based catalysts under similar experimental condition. Further, the electrochemical supercapacitor measurements (in three-electrode system) reveal that the NIT1 electrode possesses much higher specific capacity of 187.6 C g-1 at a current density of 2 A g-1 (272 C g-1 at 5 mV s-1) with capacitance retention of 75.2% over 10,000 cycles at 14 A g-1 (Coulombic efficiency > 99%) in 6 M KOH electrolyte medium. Finally for a practical application, an asymmetric supercapacitor device (coin cell) is assembled by NIT1 material. The as-fabricated device delivers the maximum energy density of 39.4 Wh kg-1 at a power density of 450 W kg-1 and achieves a wide voltage window of 1.80 V. Notably, the device endures a remarkable cycle performance with cyclic retention of 92% (Coulombic efficiency > 99%) even after 14,000 charge/discharge cycles at 10 A g-1. Nevertheless, the extraordinary electrochemical activities toward OER and HER as well as the high-performance device fabrication for LED illumination of such a noble metal-free lower-dimensional charge-transfer compound are truly path breaking and would be promising for the development of advanced multifunctional materials.

Intrinsic Specific Activity Enhancement for Bifunctional Electrocatalytic Activity toward Oxygen and Hydrogen Evolution Reactions via Structural Modification of Nickel Organophosphonates.

A comprehensive knowledge of the structure-activity relationship of the framework material is decisive to develop efficient multifunctional electrocatalysts. In this regard, two different metal organophosphonate compounds, [Ni(Hhedp)2]·4H2O (I) and [Ni3(H3hedp)2(C4H4N2)3]·6H2O (II) have been isolated through one-pot hydrothermal strategy by using H4hedp (1-hydroxyethane 1,1-diphosphonic acid) and N-donor auxiliary ligand (pyrazine; C4H4N2). The structures of synthesized materials have been established through single-crystal X-ray diffraction studies, which confirm that compound I formed a one-dimensional molecular chain structure, while compound II exhibited a three-dimensional extended structure. Further, the crystalline materials have participated as efficient electrocatalysts for the oxygen evolution and hydrogen evolution reactions (OER and HER) as compared to the state-of-the-art electrocatalyst RuO2. The electrocatalytic OER and HER performances show that compound II displayed better electrocatalytic performances toward OER (η10 = 305 mV) and HER (η10 = 230 mV) in alkaline (1 M KOH) and acidic (0.5 M H2SO4) media, respectively. Substantially, the specific activity has been assessed in order to measure the inherent electrocatalytic activity of the title electrocatalyst, which displays an enrichment of fourfold higher activity of compound II (0.64 mA/cm2) than compound I (0.16 mA/cm2) for the OER experiments. Remarkably, inclusion of an auxiliary pyrazine ligand into the metal organophosphonate structure (compound II) not only offers higher dimensionality along with significant enhancement of the overall bifunctional electrocatalytic performances but also improves the long-term stability, which is noteworthy for the family of hybrid framework materials.

Porous nanorods by stacked NiO nanoparticulate exhibiting corn-like structure for sustainable environmental and energy applications.

A porous 1D nanostructure provides much shorter electron transport pathways, thereby helping to improve the life cycle of the device and overcome poor ionic and electronic conductivity, interfacial impedance between electrode-electrolyte interface, and low volumetric energy density. In view of this, we report on the feasibility of 1D porous NiO nanorods comprising interlocked NiO nanoparticles as an active electrode for capturing greenhouse CO2, effective supercapacitors, and efficient electrocatalytic water-splitting applications. The nanorods with a size less than 100 nm were formed by stacking cubic crystalline NiO nanoparticles with dimensions less than 10 nm, providing the necessary porosity. The existence of Ni2+ and its octahedral coordination with O2- is corroborated by XPS and EXAFS. The SAXS profile and BET analysis showed 84.731 m2 g-1 surface area for the porous NiO nanorods. The NiO nanorods provided significant surface-area and the active-surface-sites thus yielded a CO2 uptake of 63 mmol g-1 at 273 K via physisorption, a specific-capacitance (CS) of 368 F g-1, along with a retention of 76.84% after 2500 cycles, and worthy electrocatalytic water splitting with an overpotential of 345 and 441 mV for HER and OER activities, respectively. Therefore, the porous 1D NiO as an active electrode shows multifunctionality toward sustainable environmental and energy applications.

Access to carbon nanofiber composite hydrated cobalt phosphate nanostructure as an efficient catalyst for the hydrogen evolution reaction.

Attractive technology for producing sustainable hydrogen with water electrolyzers was foreseen as one of the most promising ways to meet the increasing demands of renewable resources and electricity storage. Mainly used for the efficient generation of H2, water electrolysis involving hydrogen evolution reactions (HERs) depends on efficient and affordable electrocatalysts. Hydrogen is an effective fuel that can be produced by splitting water. Hence, the search for highly efficient HER catalysts is a major challenge as efficient hydrogen evolution catalysts are sought to replace catalysts such as platinum. Here, we describe a low-cost and highly effective electrocatalyst for the proper incorporation of the HER electrocatalyst with low overpotential, effective charge transfer kinetics, low Tafel slope, and good durability. By using a simple hydrothermal approach to produce Co3(PO4)2.8H2O/CNF, it is possible to attach Co3(PO4)2.8H2O to the surface of carbon nanofibers (CNFs), which also exhibit remarkable HER activity at an overpotential of 133 mV and produce a current density of 10 mA/cm2 and a 48 mV/decade for the Tafel slope. Large electrochemical surface areas and easy charge transfer from Co3(PO4)2.8H2O to the electrode through conductive Co3(PO4)2.8H2O/CNF composites are the reasons for the improved performance of Co3(PO4)2.8H2O/CNF.

Unraveling the Role of Orbital Interaction in the Electrochemical HER of the Trimetallic AgAuCu Nanobowl Catalyst.

Unraveling the origins of the electrocatalytic activity of composite nanomaterials is crucial but inherently challenging. Here, we present a comprehensive investigation of the influence of different orbitals' interaction in the AuAgCu nanobowl model electrocatalyst during the hydrogen evolution reaction (HER). According to our theoretical study, AgAuCu exhibits a lower energy barrier than AgAu and AgCu bimetallic systems for the HER, suggesting that the trimetallic AgAuCu system interacts optimally with H*, resulting in the most efficient HER catalyst. As we delve deeper into the HER activity of AgAuCu, it was observed that the presence of Cu allows Au to adsorb the H* intermediate through the hybridization of s orbitals of hydrogen and s, dx2-y2, and dz2 orbitals of Au. Such orbital interaction was not present in the cases of AgAu and AgCu bimetallic systems, and as a result, these bimetallic systems exhibit lower HER activities.

Facile Fabrication of Ni9 S8 /Ag2 S Intertwined Structures for Oxygen and Hydrogen Evolution Reactions.

Here, we report the fabrication of the unique intertwined Ni9 S8 /Ag2 S composite structure with hexagonal shape from their molecular precursors by one-pot thermal decomposition. Various spectroscopic and microscopic techniques were utilized to confirm the Ni9 S8 /Ag2 S intertwined structure. Powder X-ray Powder Diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analysis suggest that there is an enrichment of Ni9 S8 phase in Ni9 S8 /Ag2 S. The presence of Ag2 S in Ni9 S8 /Ag2 S improves the conductivity by reducing the interfacial energy and charge transfer resistance. When Ni9 S8 /Ag2 S is employed as an electrocatalyst for electrochemical oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) activity, it requires a low overpotential of 152 mV for HER and 277 mV for OER to obtain the geometrical current density of 10 mA cm-2 , which is definitely superior to that of its components Ni9 S8 and Ag2 S. This work provides a simple design route to develop an efficient and durable electrocatalyst with outstanding OER and HER performance and the present catalyst (Ni9 S8 /Ag2 S) deserves as a potential candidate in the field of energy conversion systems.

Brønsted acid catalyzed mechanochemical domino multicomponent reactions by employing liquid assisted grindstone chemistry.

Here, we have demonstrated a metal-free energy-efficient mechanochemical approach for expedient access to a diverse set of 2-amino-3-cyano-aryl/heteroaryl-4H-chromenes, tetrahydrospiro[chromene-3,4'-indoline], 2,2'-aryl/heteroarylmethylene-bis(3-hydroxy-5,5-dimethylcyclohex-2-enone) as well as tetrahydro-1H-xanthen-1-one by employing the reactivity of 5,5-dimethylcyclohexane-1,3-dione/cyclohexane-1,3-dione with TsOH⋅H2O as Brønsted acid catalyst under water-assisted grinding conditions at ambient temperature. The ability to accomplish multiple C-C, C=C, C-O, and C-N bonds from readily available starting materials via a domino multicomponent strategy in the absence of metal-catalyst as well as volatile organic solvents with an immediate reduction in the cost of the transformation without necessitates complex operational procedures, features the significant highlights of this approach. The excellent yield of the products, broad functional group tolerances, easy set-up, column-free, scalable synthesis with ultralow catalyst loading, short reaction time, waste-free, ligand-free, and toxic-free, are other notable advantages of this approach. The greenness and sustainability of the protocol were also established by demonstrating several green metrics parameters.

Reduced graphene oxide doped tellurium nanotubes for high performance supercapacitor.

Supercapacitors have been achieving great interest in energy storage systems for the past couple of decades. Such devices with superior performance, mainly, depending on the material architecture of the electrodes. We report on the preparation of Tellurium nanotubes (Te-tubes diameter ∼100 nm and length ∼700 nm), with variable doping of conducting network reduced graphene oxide (rGO) to fabricate high-performance electrode characteristics of rGO @ Te. The prepared material was characterized using XRD, FTIR, FESEM, and Raman spectroscopy techniques, including Brunauer-Emmett-Teller, Barrett-Joyner-Halenda measurements. FTIR study revealed that 15% rGO @ Te has a wide C-O vibration band at ∼ 1,100-1,300 cm-1, over other compositions. FESEM study shows the Te-tubes dispersion in rGO layers. The EDX study revealed that 15% of the composition has an optimistic concentration of C and O elements. In other compositions, either at lower/higher rGO concentration, an uneven count of C and O is observed. These support efficient charge dynamics to achieve superior ultra-capacitor characteristics, thereby achieving specific capacitance Csp 170 + F/g @ 10 mV/s in a symmetric configuration. The reported values are thirty times higher than pristine Te-tubes (∼5 F/g). This finding suggests that rGO @ Te is a promising candidate for supercapacitor.

Dithiophosphonate Anchored Heterometallic (Ag(I)/Fe(II)) Molecular Catalysts for Electrochemical Hydrogen Evolution Reaction.

The dichalcogenide ligated molecules in catalysis to produce molecular hydrogen through electroreduction of water are rarely explored. Here, a series of heterometallic [Ag4(S2PFc(OR)4] [where Fc = Fe(η5-C5H4)(η5-C5H5), R = Me, 1; Et, 2; nPr, 3; isoAmyl, 4] clusters were synthesized and characterized by IR, absorption spectroscopy, NMR (1H, 31P), and electrospray ionization mass spectrometry. The molecular structures of 1, 2, and 3 clusters were established by single-crystal X-ray crystallographic analysis. The structural elucidation shows that each triangular face of a tetrahedral silver(I) core is capped by a ferrocenyl dithiophosphonate ligand in a trimetallic triconnective (η3; µ2, µ1) pattern. A comparative electrocatalytic hydrogen evolution reaction of 1-5 (R = iPr, 5) was studied in order to demonstrate the potential of these clusters in water splitting activity. The experimental results reveal that catalytic performance decreases with increases in the length of the carbon chain and branching within the alkoxy (-OR) group of these clusters. Catalytic durability was found effective even after 8 h of a chronoamperometric stability test along with 1500 cycles of linear sweep voltammetry performance, and only 15 mV overpotential was increased at 5 mA/cm2 current density for cluster 1. A catalytic mechanism was proposed by applying density functional theory (DFT) on clusters 1 and 2 as a representative. Here, a µ1 coordinated S-site between Ag4 core and ligand was found a reaction center. The experimental results are also in good accordance with the DFT analysis.

Genomic DNA-mediated formation of a porous Cu2(OH)PO4/Co3(PO4)2·8H2O rolling pin shape bifunctional electrocatalyst for water splitting reactions.

Among the accessible techniques, the production of hydrogen by electrocatalytic water oxidation is the most established process, which comprises oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). Here, we synthesized a genomic DNA-guided porous Cu2(OH)PO4/Co3(PO4)2·8H2O rolling pin shape composite structure in one pot. The nucleation and development of the porous rolling pin shape Cu2(OH)PO4/Co3(PO4)2·8H2O composite was controlled and stabilized by the DNA biomolecules. This porous rolling pin shape composite was explored towards electrocatalytic water oxidation for both OER and HER as a bi-functional catalyst. The as-prepared catalyst exhibited a very high OER and HER activity compared to its various counterparts in the absence of an external binder (such as Nafion). The synergistic effects between Cu and Co metals together with the porous structure of the composite greatly helped in enhancing the catalytic activity. These outcomes undoubtedly demonstrated the beneficial utilization of the genomic DNA-stabilised porous electrocatalyst for OER and HER, which has never been observed.

Dumbbell-Shaped Ternary Transition-Metal (Cu, Ni, Co) Phosphate Bundles: A Promising Catalyst for the Oxygen Evolution Reaction.

Development of economical and high-performance electrocatalysts for the oxygen evolution reaction (OER) is of tremendous interest for future applications as sustainable energy materials. Here, a unique member of efficient OER electrocatalysts has been developed based upon structurally versatile dumbbell-shaped ternary transition-metal (Cu, Ni, Co) phosphates with a three-dimensional (3D) (Cu2(OH)(PO4)/Ni3(PO4)2·8H2O/Co3(PO4)2·8H2O) (CNCP) structure. This structure is prepared using a simple aqueous stepwise addition of metal ion source approach. Various structural investigations demonstrate highly crystalline nature of the composite structure. Apart from the unique structural aspect, it is important that the CNCP composite structure has proved to be an excellent electrocatalyst for OER performance in comparison with its binary or constituent phosphate under alkaline and neutral conditions. Notably, the CNCP electrocatalyst displays a much lower overpotential of 224 mV at a current density of 10 mA cm-2 and a lower Tafel slope of 53 mV dec-1 with high stability in alkaline medium. In addition, X-ray photoelectron spectroscopy analysis suggested that the activity and long-term durability for the OER of the ternary 3D metal phosphate are due to the presence of electrochemically dynamic constituents such as Ni and Co and their resulting synergistic effects, which was further supported by theoretical studies. Theoretical calculations also reveal that the incredible OER execution was ascribed to the electron redistribution set off in the presence of Ni and Cu and the most favorable interaction between the *OOH intermediate and the active sites of CNCP. This work may attract the attention of researchers to construct efficient 3D ternary metal phosphate catalysts for various applications in the field of electrochemistry.

Charge Separated One-Dimensional Hybrid Cobalt/Nickel Phosphonate Frameworks: A Facile Approach to Design Bifunctional Electrocatalyst for Oxygen Evolution and Hydrogen Evolution Reactions.

Two new organoamine templated one-dimensional transition metal phosphonate compounds are synthesized, and their bifunctional electrocatalytic activities are examined in highly alkaline and acidic media. Compared with state-of-the-art materials, the cobalt phosphonate system is a new fabrication of sustainable and highly efficient catalysts toward electrochemical water splitting systems.

Interfacial Engineering of CuCo2S4/g-C3N4 Hybrid Nanorods for Efficient Oxygen Evolution Reaction.

Altering the morphology of electrochemically active nanostructured materials could fundamentally influence their subsequent catalytic as well as oxygen evolution reaction (OER) performance. Enhanced OER activity for mixed-metal spinel-type sulfide (CuCo2S4) nanorods is generally done by blending the material that has high conductive supports together with those having a high surface volume ratio, for example, graphitic carbon nitrides (g-C3N4). Here, we report a noble-metal-free CuCo2S4 nanorod-based electrocatalyst appropriate for basic OER and neutral media, through a simple one-step thermal decomposition approach from its molecular precursors pyrrolidine dithiocarbamate-copper(II), Cu[PDTC]2, and pyrrolidine dithiocarbamate-cobalt(II), Co[PDTC]2 complexes. Transmission electron microscopy (TEM) images as well as X-ray diffraction (XRD) patterns suggest that as-synthesized CuCo2S4 nanorods are highly crystalline in nature and are connected on the g-C3N4 support. Attenuated total reflectance-Fourier-transform infrared (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy studies affirm the successful formation of bonds that bridge (Co-N/S-C) at the interface of CuCo2S4 nanorods and g-C3N4. The kinetics of the reaction are expedited, as these bridging bonds function as an electron transport chain, empowering OER electrocatalytically under a low overpotential (242 mV) of a current density at 10 mA cm-2 under basic conditions, resulting in very high durability. Moreover, CuCo2S4/g-C3N4 composite nanorods exhibit a high catalytic activity of OER under a neutral medium at an overpotential of 406 mV and a current density of 10 mA cm-2.

Noble copper-silver-gold trimetallic nanobowls: An efficient catalyst.

We demonstrated the design of tiny bowls of copper-silver-gold (Cu-Ag-Au) alloy type noble trimetallic nanocrystals with a unique shape. All the structural characterizations confirm the presence of copper (Cu), silver (Ag), and gold (Au) in the trimetallic nanobowls. Finally, we examined the catalytic efficiency of trimetallic Cu-Ag-Au nanobowls for reduction of 4-nitrophenol to 4-aminophenol and found that these nanobowls were 14, 23 and 43-fold more active than each of the constituent metals, Au, Cu and Ag, respectively.

An approach to incompatible cross-matched red cells: Our experience in a major regional blood transfusion center at Kolkata, Eastern India.

INTRODUCTION: With the increased utilization of immunohematology (IH) analyzers in the transfusion medicine, type, and screen policy is the method of choice. Still, the importance of routine crossmatching could not be overruled. Here, we tried to understand the clinical conditions and safety of red cell transfusion and their outcomes. MATERIALS AND METHODS: This prospective study was conducted by IH laboratory, Medical College Kolkata, Blood Bank from October 1, 2015 to March 31, 2016. A set of 3cc ethylenediaminetetraacetic acid and clotted blood samples of the patients were received according to sample acceptance criteria. Blood grouping by conventional tube technique followed by crossmatching was performed by column agglutination technology (CAT) in polyspecific (IgG + C3d) gel media. Any positive result was rechecked in duplicate with additional two group-specific donor units. The persistent incompatibility was further evaluated using direct anti-human globulin test, auto control, antibody screening, and antibody identification by CAT. RESULTS: On the evaluation of 14,387 sets of patients' sample, only 100 were found to be incompatible (0.69%). Incompatibility rate is higher in females (59%). Eighty-five of these patients were repeatedly transfused. Only 38% of incompatible crossmatch were positive on indirect anti-human globulin test/antibody screening. Antibody could be identified in 16 of them. Seventeen of 100 incompatible samples (17%) presented with panagglutination, were managed with Rh, Kell phenotype/best-matched red cell units. In these 16 patients, 23 alloantibodies were identified; allo anti-E was the most common. CONCLUSION: This study showed antibody against the Rh system as the most common cause of incompatibility.