Monthly Archives: March 2024

Preparation of SnO2@graphite Anode based on the Oriented Deposition Methodology with Superior Electrode Behavior for Li Ion Battery

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Preparation of SnO2@graphite Anode based on the Oriented Deposition Methodology with Superior Electrode Behavior for Li Ion Battery

SnO2@graphite composite derived from the oriented deposition methodology is employed as the anode material for LIBs. The SnO2@graphite electrode exhibits satisfactory electrode behavior with respect to capacity, rate capability and durability. Besides, the SnO2@graphite/LiFePO4 full cell exhibits higher energy and power densities over that of graphite/LiFePO4 full cell.


Abstract

SnO2-based anode materials are deemed to be one of the most prospective anode materials for Li ion batteries (LIBs) with higher theoretical capacity as compared to conventional graphite. However, the weak electrical conduction and large volume expansion limit its application in eVeryday life. Here, a simple and low-cost oriented deposition methodology is developed to prepare SnO2@graphite composite, which is obtained based on the redox reaction mechanism between SnSO4 and graphite. SnO2 nanoparticles are uniformly anchored on the carbon layer of graphite. The close anchoring of SnO2 in graphite effectively inhibits the volume expansion of SnO2 during lithiation/delithiation processes, and good combination state between them guarantees the excellent electrical conductivity of the composite. As anode for LIBs, SnO2@graphite electrode delivers superior reversible capacity and provides an improved rate capability compared to graphite electrode. Benefiting from the tight combination of SnO2 and graphite, the Li ion diffusion coefficient of SnO2@graphite electrode is almost twice that of graphite electrode. Pairing with LiFePO4 cathode, the SnO2@graphite/LiFePO4 full cell exhibits higher energy/power densities by comparison with graphite/LiFePO4. Besides, this advanced SnO2@graphite composite material with superior anode behavior can be mass produced by the reported methodology.

An Overview on Lead Halide Perovskite based Composites and Heterostructures: Synthesis and Applications

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An Overview on Lead Halide Perovskite based Composites and Heterostructures: Synthesis and Applications

Lead halide perovskites find numerous applications owing to the photophysical properties but faces glaring stability issues. Heterostructures and composites based on lead halide perovskites leads to improved and stable applications. This review explores the synthesis methods followed to produce these hybrid materials focusing on the improvements required in fundamental studies and their applications.


Abstract

Lead Halide Perovskites (LHPs) have garnered great attention in recent times due to their astonishing properties that range from direct tunable bandgaps, strong light absorption, defect resistance and the easily accessible synthesis of high-quality crystals and films. These materials find application in multitudinous fields including photovoltaics, optoelectronics, lasers, catalysis and in the emerging field of spintronics. Though they show exceptional optoelectronic properties with enhanced applications, the instability of LHPs act as a main downside when it comes to real world applications. Integrating complementary materials to LHPs that form composites with better stability along with improved performance have started to gain traction. These composites and heterostructures incorporating functional materials with LHPs have made the utilization of perovskites in everyday life more feasible. The existing synthetic strategies for heterostructure and composites heavily draw from the techniques used for halide perovskite synthesis. These methods often under-utilize the potential of exploring the synergy of materials interaction. This review explores the synthesis methods followed to produce these hybrid materials focusing on the improvements required in terms of fundamental studies and their applications.

Dispersed Nickel Phosphide Cocatalyst on Nb2O5 Ultrathin Nanosheets to Boost Photocatalytic CO2 Reduction

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Dispersed Nickel Phosphide Cocatalyst on Nb2O5 Ultrathin Nanosheets to Boost Photocatalytic CO2 Reduction

Tiny NiP nanoparticles dispersed was used as an inexpensive, stable, and active cocatalysts on ultrathin Nb2O5 nanosheets to replace the noble metal Pt. Owing to the extended light harvesting, enhanced carrier separation, and improved surface reaction, the NiP/Nb2O5 exhibits even higher activity and selectivity towards CO2 photocatalytic reduction. And the roles and function mechanisms of the cocatalyst were studied.


Abstract

Photocatalytic CO2 reduction holds great promise to solve energy shortage and global warming. Nb2O5 has demonstrated superiority in CO2 activation and selectivity regulation, but suffers from poor light absorption ability and fast carrier recombination. To tackle these problems, we designed and synthesized ultrathin Nb2O5 nanosheets which were decorated with tiny NiP nanoparticles as cocatalyst. In this way, light absorption range broadened, carrier migration distance reduced, charge transfer resistance decreased, and surface reaction kinetics promoted. Consequently, the as-prepared NiP/Nb2O5 showed notably enhanced activity (148.7 μmol ⋅ g−1) and selectivity (82.1 %) towards CO, as well as remarkable stability. This work paves the way for cheap and earth abundant alternatives as cocatalysts and deepens the understanding of their functions in CO2 photoreduction.

A Facile Synthetic Approach for TiO2@NiO Core‐shell Nanoparticles using TiO2@Ni(OH)2 Precursors and their Photocatalytic Application

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A Facile Synthetic Approach for TiO2@NiO Core-shell Nanoparticles using TiO2@Ni(OH)2 Precursors and their Photocatalytic Application

TiO2@NiO core-shell nanoparticles, synthesized using TiO2@Ni(OH)2 as precursors, show better photocatalytic activity compared to pure TiO2 and NiO nanoparticles.


Abstract

The current study presents a simple and an efficient chemical method for the synthesis of TiO2@NiO core-shell nanoparticles (CSNPs) as photocatalyst for effective degradation of rhodamine B (RhB) in an aqueous solution upon sunlight irradiation. First, TiO2 spheres were synthesized using a wet chemical method. Then, TiO2@Ni(OH)2 precursors were prepared via homogeneous precipitation and TiO2@NiO core-shell nanoparticles were obtained on calcination of the precursors. The synthesized precursors and the TiO2@NiO CSNPs were analyzed using XRD, FT-IR, FESEM and DRS. XRD data shows the presence of both TiO2 and NiO phases in the TiO2@NiO samples. FE-SEM and TEM analyses confirm coating of NiO NPs on TiO2 spheres with varying shell thickness (40 nm to 170 nm). Optical studies reveal that TiO2@NiO CSNPs possess band gap of about 3.7 eV. Photoluminescence (PL) results show lower recombination rate of e− and h+ pairs in the TiO2@NiO CSNPs. XPS studies confirm the presence of different elements in the TiO2@NiO CSNPs. Magnetic investigations reveal ferromagnetic behavior of the core-shell NPs at 5 K. The TiO2@NiO CSNPs were explored as photocatalyst for the degradation of rhodamine B in water under natural sunlight. The TiO2@NiO CSNPs exhibit better photocatalytic activity compared to TiO2 and NiO nanoparticles.

Nickel Oxide Decorated MWCNTs Wrapped Polypyrrole: One Dimensional Ternary Nanocomposites for Enhanced Thermoelectric Performance

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Nickel Oxide Decorated MWCNTs Wrapped Polypyrrole: One Dimensional Ternary Nanocomposites for Enhanced Thermoelectric Performance

In-situ generation of nickel oxide nanoparticles (NiO) on functionalized multi-walled carbon nanotubes (MWCNTs-(COOH)3) was successfully achieved, this latter was wrapped with polypyrrole (PPy) nanotubes resulting in a high figure of merit (ZT=1.51×10−2 at RT) compared to PPy alone. This hybrid organic-inorganic nanocomposite material offers the potential for waste heat recovery.


Abstract

This study reports on a customized and revised approach to fabricate “nickel oxide decorated multi-walled carbon nanotubes (MWCNTs) wrapped polypyrrole (PPy)” nanocomposite with enhanced room-temperature thermoelectric (TE) properties. The nanocomposite is formed through three steps: MWCNTs functionalization via diazonium salt grafting of 5-amino-1,2,3-benzene tricarboxylic acid; in situ generation on their surfaces of NiO nanoparticles with a homogenous distribution; the chemical polymerization of pyrrole using methyl orange as templating and dopant to wrap the MWCNTs-(COOH)3-NiO. Various techniques were used as characterization tools, including XRD, TEM, FTIR, Raman, TGA, XPS, and TE measurements. The PPy-MWCNTs-(COOH)3-NiO nanocomposite exhibits significantly higher Seebeck coefficient, electrical conductivity, and power factor than PPy and PPy-MWCNTs-(COOH)3. The achieved enhancement in TE properties (figure of merit, ZTPPy-MWCNTs-(COOH)3-NiO=1.51×10−2) is attributed to the presence of NiO, which acts as a dopant and improves the charge carrier density in the nanocomposite. These results offer the potential for waste heat recovery and large-scale fabrication of high-performance composites.

(B, N)‐Rich B−C−N Nanosheet‐assembled Microwires as Effective Electrocatalysts for Oxygen Reduction Reaction

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(B, N)-Rich B−C−N Nanosheet-assembled Microwires as Effective Electrocatalysts for Oxygen Reduction Reaction

B, N-rich BCNNAM (nanosheet-assembled microwires), produced via a conbining growth mechanism of VLS and VS, showed excellent electrocatalytic performances for ORR due to synergistic effect arising from B, C and N as well as hierarchical porous structure.


Abstract

Developing highly active and stable nanocarbon electrocatalysts for the oxygen reduction reaction (ORR) in alkaline medium has attracted much attention due to their potential as an alternative to traditional metal-based or noble metal catalysts. Herein, a unique micro-nano structure of (B, N)-rich B−C−N nanosheet-assembled microwires (BCNNAM) were synthesized and driven electrochemical oxide reduction reaction. The diameter of the microwires about 1 μm, while the nanosheets have an average thickness of less than 20 nm. The compact nanosheets are mostly separated with a bending, curling and crumpling morphology. All those constitutes a ternary system with large surface area and abundant activity sites facilitate fast mass/electron transport for ORR catalytic activity. Thus, the B, N-rich B−C−N nanosheet-assembled microwires show significantly improved electrocatalytic activity with an onset potential of 0.95 V and half-wave potential of 0.83 V compared to BNNAM, nitride-doped carbon, porous carbon and a commercial Pt/C electrocatalyst. Such high catalytic performance of B, N-rich B−C−N micro-nano structures is due to the enhanced activity by the coexistence of B, C and N and the mass transfer promoted by the unique hierarchical porous structure.

Synthesis of a novel fused thieno‐pyrimidine with tetrazole analogs

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Synthesis of a novel fused thieno-pyrimidine with tetrazole analogs

Synthesis of new fused thieno-pyrimidine with tetrazole analogs.


Abstract

This current investigation represents the new series of fused thieno-pyrimidine with synthesized tetrazole analogs (6a–j). Intermediates thieno-[2,3-d]-pyrimidine were prepared by utilizing the Gewald method, and tetrazole (5a–j) was synthesized by [3 + 2] cycloaddition of azide and appropriate nitrile. All the prepared novel molecules were characterized and confirmed by 1HNMR, 13CNMR, LC-MS, and FT-IR spectral analysis.

Molecular Complexes for Catalytic Ammonia Oxidation to Dinitrogen and the Cleavage of N−H Bonds

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Molecular Complexes for Catalytic Ammonia Oxidation to Dinitrogen and the Cleavage of N−H Bonds

Molecular systems, including homogeneous transition metals complexes and those of main group elements, are examined to illustrate the various types of stoichiometric N−H bond cleavage reactions. Molecular complexes that mediate catalytic NH3 oxidation to N2 through chemically or electrochemically driven reactions are described.


Abstract

The molecular complexes described herein use main-group elements or transition metals to control the stoichiometric cleavage of N−H bonds of ammonia (NH3) and/or catalyze chemical and electrochemical NH3 oxidation to dinitrogen (N2). We highlight the phenomenon of coordination-induced bond weakening and a variety of N−H bond cleavage mechanisms of NH3 including H atom abstraction, inter- and intra-molecular deprotonation reactions, oxidative addition, and σ -bond metathesis that have been demonstrated with molecular systems. We provide an overview of the molecular complexes reported for the rapidly developing field of NH3 oxidation catalysis to form N2. These systems exhibit several diverse structure types and innovative ligands to support transition metals capable of activating NH3 and mediating a challenging chemical transformation that requires breaking strong N−H bonds and forming an N−N bond en route to N2 formation.

An Overview of Syntheses of Salvinorin A and its Analogues

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An Overview of Syntheses of Salvinorin A and its Analogues

Salvinorin A, a potent human hallucinogen, uniquely activates the kappa-opioid receptor (κ-OR) with high efficacy and selectivity. Its novel structure lacks nitrogenous components, distinguishing it from other opioids. With a complex trans-decalin core and δ-lactone fused with a furan moiety, synthetic access to Salvinorin A remains challenging due to a sensitive epimerizable center. Despite considerable synthetic efforts, only nine syntheses have been produced. This review aims to offer insights into the primary strategies employed to accomplish the syntheses documented thus far.


Abstract

Salvinorin A is a powerful hallucinogen in humans, and a selective, high efficacy agonist of the kappa-opioid receptor (κ-OR). Salvinorin A is the first plant-derived ligand with high selectivity for κ-OR over other receptors, its structure is unrelated to any known opioid receptor ligands, even lacking any nitrogenous moieties. Mechanistically and pharmacologically, salvinorin A is distinct from other known hallucinogens in humans, making it the only selective κ-OR ligand to gain wide-spread interest outside of research. Structurally, salvinorin A bares a highly functionalized trans-decalin core, containing two quaternary centers, and is fused to a δ-lactone baring a furan moiety. Synthetic access of salvinorin A has been elusive due to a highly sensitive epimerizable center at carbon 8 (C8). All these features make salvinorin A a highly challenging synthetic target. With multiple synthetic efforts from around the world, only nine completed syntheses have been achieved to date. This review is intended to provide a look at the key strategies used to achieve the syntheses reported to date. We will summarize the efforts towards the syntheses of salvinorin A starting from Evans in 2007 to Barriault in 2023.