Molecular Cluster Complex of High-Valence Chromium Selenide Carbonyl as Effective Electrocatalyst for Water Oxidation

Developing Simple, Affordable, and Environmentally Friendly Water Oxidation Electrocatalysts with High Intrinsic Activity and Low overpotential Continues to Be an Area of Intense Research. in This Article, a Trichromium Diselenide Carbonyl Cluster Complex (Et4N)2[Se2Cr3(CO)10], with a Unique Bonding Structure Comprising Bridging Se Groups, Has Been Identified as a Promising Electrocatalyst for Oxygen Evolution Reaction (OER). This Carbonyl Cluster Exhibits a Promising overpotential of 310 MV and a Low Tafel Slope of 82.0 MV Dec−1 at 10 MAcm−2, with Superior Durability in an Alkaline Medium, for a Prolonged Period of Continuous Oxygen Evolution. the Mass Activity and Turnover Frequency of 62.2 Ag−1 and 0.0174 S−1 Was Achieved, Respectively at 0.390 V vs.. RHE. the Cr-Complex Reported Here Shows Distinctly Different Catalytic Activity based on Subtle Changes in the Ligand Chemistry Around the Catalytically Active Cr Site. Such Dependence Further Corroborates the Critical Influence of Ligand Coordination on the Electron Density Distribution Which Further Affects the Electrochemical Activation and Catalytic Efficiency of the Active Site. Specifically, Even Partial Substitution with More Electronegative Substituents Leads to the Weakening of the Catalytic Efficiency. This Report Further Demonstrates that Metal Carbonyl Chalcogenides Cluster-Type Materials Which Exhibit Partially Occupied Sites and High Valence in their Metal Sites Can Serve as Catalytically Active Centers to Catalyze OER Exhibiting High Intrinsic Activity. the Insight Generated from This Report Can Be Directly Extrapolated to 3-Dimensional Solids Containing Similar Structural Motifs, Thereby Aiding in Optimal Catalyst Design

CuInSe₂ Nanotube Arrays for Efficient Solar Energy Conversion

Highly uniform and vertically aligned p-type CuInSe2 (CISe) nanotube arrays were fabricated through a unique protocol, incorporating confined electrodeposition on lithographically patterned nanoelectrodes. This protocol can be readily adapted to fabricate nanotube arrays of other photoabsorber and functional materials with precisely controllable design parameters. Ternary CISe nanotube arrays were electrodeposited congruently from a single electrolytic bath and the resulting nanotube arrays were studied through powder X-ray diffraction as well as elemental analysis which revealed compositional purity. Detailed photoelectrochemical (PEC) characterizations in a liquid junction cell were also carried out to investigate the photoconversion efficiency. It was observed that the tubular geometry had a strong influence on the photocurrent response and a 29.9% improvement of the photoconversion efficiency was observed with the nanotube array compared to a thin film geometry fabricated by the same process. More interestingly such enhancement in photoconversion efficiency was obtained when the electrode coverage with the nanotube arrays as photoactive material was only a fraction (~10%) of that for the thin film device. Apart from enhancement in photoconversion efficiency, this versatile technique provides ample opportunities to study novel photovoltaic materials and device design architectures where structural parameters play a key role such as resonant light trapping

Growth of Ordered Nanostructure Arrays Including Nanotubes and Nanorods for High Efficiency Solar Cells

A simple and straightforward approach has been described for the fabrication of CdTe nanotube and nanorod arrays with a high degree of precision through confined electrodeposition on lithographically patterned nanoelectrodes. This technique has the potential of growing these nanotube/nanowire arrays with extreme uniformity over a significantly large area. the desired nanoelectrode pattern was defined through electron beam lithography on indium tin oxide coated glass, and electrodeposition of the semiconducting material of interest (CdTe) on the nanoelecrodes produced the nanotubes/nanowires. It is interesting to note that the measured photocurrent density of nanotube device created by this protocol exceeds that obtained from a thin film device fabricated under similar conditions by several orders of magnitude. the ability to fine tune all the physical dimensions and distribution density of the nanostructures, make this method a versatile tool to fabricate and investigate nano-structured photovoltaic devices and study their structure-property relationship. Additionally the ability to create uniform nano-feature arrays in addition to nanotube/nanorod arrays through one-step electrodeposition makes this protocol unique

Generalized Synthesis of EAs [E = Fe, Co, Mn, Cr] Nanostructures and Investigating their Morphology Evolution

This paper illustrates a novel route for the synthesis of nanostructured transition metal arsenides including those of FeAs, CoAs, MnAs, and CrAs through a generalized protocol. The key feature of the method is the use of one-step hot-injection and the clever use of a combination of precursors which are low-melting and highly reactive such as metal carbonyls and triphenylarsine in a solventless setup. This method also facilitates the formation of one-dimensional nanostructures as we move across the periodic table from CrAs to CoAs. The chemical basis of this reaction is simple redox chemistry between the transition metals, wherein the transition metal is oxidized from elemental state (E0) to E3+ in lieu of reduction of As3+ to As3-. While the thermodynamic analysis reveals that all these conversions are spontaneous, it is the kinetics of the process that influences morphology of the product nanostructures, which varies from extremely small nanoparticles to nanorods. Transition metal pnictides show interesting magnetic properties and these nanostructures can serve as model systems for the exploration of their intricate magnetism as well as their applications and can also function as starting materials for the arsenide based nanosuperconductors

Cobalt Telluride Electrocatalyst for Selective Electroreduction of CO2 to Value-Added Chemicals

Recent emphasis on carbon dioxide utilization has necessitated the exploration of different catalyst compositions other than copper-based systems that can significantly improve the activity and selectivity towards specific CO2 reduction products at low applied potential. In this study, a binary CoTe has been reported as an efficient electrocatalyst for CO2 reduction in aqueous medium under ambient conditions at neutral pH. CoTe showed high Faradaic efficiency and selectivity of 86.83 and 75%, respectively, for acetic acid at very low potential of − 0.25 V vs RHE. More intriguingly, C1 products like formic acid was formed preferentially at slightly higher applied potential achieving high formation rate of 547.24 μmol cm−2 h−1 at − 1.1 V vs RHE. CoTe showed better CO2RR activity when compared with Co3O4, which can be attributed to the enhanced electrochemical activity of the catalytically active transition metal center as well as improved intermediate adsorption on the catalyst surface. While reduced anion electronegativity and improved lattice covalency in tellurides enhance the electrochemical activity of Co, high d-electron density improves the intermediate CO adsorption on the catalyst site leading to CO2 reduction at lower applied potential and high selectivity for C2 products. CoTe also shows stable CO2RR catalytic activity for 50 h and low Tafel slope (50.3 mV dec–1) indicating faster reaction kinetics and robust functionality. Selective formation of value-added C2 products with low energy expense can make these catalysts potentially viable for integration with other CO2 capture technologies thereby, helping to close the carbon loop

Facile One-Pot Synthesis of NiCo₂Se₄-RGO on Ni Foam for High Performance Hybrid Supercapacitors

A facile, innovative synthesis for the fabrication of NiCo2Se4-rGO on a Ni foam nanocomposite via a simple hydrothermal reaction is proposed. The as-prepared NiCo2Se4-rGO@Ni foam electrode was tested through pxrd, TEM, SEM, and EDS to characterize the morphology and the purity of the material. The bimetallic electrode exhibited outstanding electrochemical performance with a high specific capacitance of 2038.55 F g-1 at 1 A g-1. NiCo2Se4-rGO@Ni foam exhibits an extensive cycling stability after 1000 cycles by retaining 90% of its initial capacity. A superior energy density of 67.01 W h kg-1 along with a high power density of 903.61 W kg-1 further proved the high performance of this electrode towards hybrid supercapacitors. The excellent electrochemical performance of NiCo2Se4-rGO@Ni foam can be explained through the high electrocatalytic activity of NiCo2Se4 in combination with reduced graphene oxide which increases conductivity and surface area of the electrode. This study proved that NiCo2Se4-rGO@Ni foam can be utilized as a high energy density-high power density electrode in energy storage applications

Copper Selenide as Multifunctional Non-Enzymatic Glucose and Dopamine Sensor

Cu2Se, synthesized through one-pot hydrothermal synthesis, was identified as highly efficient bifunctional sensor for co-detection of glucose and dopamine with high selectivity. As-synthesized copper selenide could electro-oxidize glucose and dopamine at different applied potentials. Glucose oxidation was observed at 0.35 V while dopamine oxidized at 0.2 V. This copper selenide-based non-enzymatic sensor showed high sensitivity for both glucose (15.341 mA mM-1 cm-2) and dopamine (12.43 μA μM-1 cm-2) with low limit of detection (0.26 μM and 84 nM). Such high sensitivity and low LOD makes this sensor attractive for possible detection of glucose/dopamine in physiological body fluids which have low concentration of these biomolecules. Extremely low applied potential for detection also makes it ideal for integrating into wearable continuous monitoring devices with low operational power requirement. This sensor showed high reproducibility, reusability and long-term operational stability along with high degree of selectivity for dopamine and glucose sensing in presence of other interferents. Graphic abstract: [Figure not available: see fulltext.]

Fabrication of Multifunctional Ferromagnetic Au₃Pd-CoSe Nanoparticles

We have synthesized multifunctional anisotropic Au3Pd-CoSe nanoparticles on Si substrate through a catalyst aided chemical vapour deposition technique. the technique utilized volatile cobalt acetylacetonate and elemental selenium as precursors while sputter coated Au-Pd (3:2) film acted as a catalyst. the typical growth conditions led to clear segregation of the hetero-compositions (i.e. Au3Pd and CoSe) in the product nanostructures thereby preserving the functionality of both the phases. the degree of crystallinity of the individual phases in the composite nanostructure was fairly high. the bifunctional nanoparticles show soft ferromagnetic behaviour at room temperature and optical activity making them ideal for opto-magnetic applications

Ultrasensitive and Highly Selective Ni₃Te₂ as a Nonenzymatic Glucose Sensor at Extremely Low Working Potential

Developing Nonenzymatic glucose biosensors has recently been at the center of attention owing to their potential application in implantable and continuous glucose monitoring systems. In this article, nickel telluride nanostructure with the generic formula of Ni3Te2 has been reported as a highly efficient electrocatalyst for glucose oxidation, functional at a low operating potential. Ni3Te2 nanostructures were prepared by two synthesis methods, direct electrodeposition on the electrode and hydrothermal method. The electrodeposited Ni3Te2 exhibited a wide linear range of response corresponding to glucose oxidation exhibiting a high sensitivity of 41.615 mA cm-2 mM-1 and a low limit of detection (LOD) of 0.43 µM. The hydrothermally synthesized Ni3Te2, on the other hand, also exhibits an ultrahigh sensitivity of 35.213 mA cm-2 mM-1 and an LOD of 0.38 µM. The observation of high efficiency for glucose oxidation for both Ni3Te2 electrodes irrespective of the synthesis method further confirms the enhanced intrinsic property of the material toward glucose oxidation. In addition to high sensitivity and low LOD, Ni3Te2 electrocatalyst also has good selectivity and long-term stability in a 0.1 M KOH solution. Since it is operative at a low applied potential of 0.35 V vs Ag|AgCl, interference from other electrochemically active species is reduced, thus increasing the accuracy of this sensor

Nanotubes of the disulfides of groups 4 and 5 metals*

Abstract: Nanotubes of HfS 2 , ZrS 2 , NbS 2 , and TaS 2 have been obtained by the reduction of the corresponding metal trisulfides in a stream of H 2 (mixed with an inert gas in some cases) at elevated temperatures. The nanotubes have been characterized by transmission electron microscopy (TEM) and other techniques. These disulfide nanotubes make an important addition to the growing family of nanotubes of inorganic layered materials