Orotic acid-capped Tb(III)-doped calcium sulphate nanorods for the selective detection of tryptophan.

Lanthanide-based luminescent materials have gained huge attention due to their applications in optoelectronic devices, sensing, bio-imaging, anti-counterfeiting, and more. In this work, we report a luminescence-based sensor for the detection of tryptophan using orotic acid-capped Tb-doped CaSO nanorods (NRs). Orotic acid (OA) was found to play a dual role as a capping agent to control the growth of the nanorods and as a sensitizer for Tb ions.

Selective Detection of Chromate and Permanganate Ions Using Gallic Acid Capped CaF:Tb Nanocrystals.

In this study, we have developed ligand-sensitized Ln-doped nanocrystals (NCs) for the selective sensing of CrO and MnO ions in nanomolar concentrations. This is accomplished with the gallic acid capped-CaF:Tb NCs. These NCs display bright green emission through an efficient energy transfer from surface functionalized gallic acid molecules to Tb ions upon UV light excitation.

Functionality Modulation Toward Thianthrene-based Metal-Free Electrocatalysts for Water Splitting.

The development of metal-free bifunctional electrocatalysts for hydrogen and oxygen evolution reactions (HER and OER) is significant but rarely demonstrated. Porous organic polymers (POPs) with well-defined electroactive functionalities show superior performance in hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Precise control of the active sites' local environment requires careful modulation of linkers through the judicious selection of building units.

Trapping and exciton-exciton annihilation assisted ultrafast carrier dynamics in nanosheets of 2H-MoSe2 and Cr doped 1T/2H-MoSe2.

Nanosheets of transition metal dichalcogenides with prospects of photocatalysis and optoelectronics applications have significant potential in device fabrication due to their low-cost production and easily controllable morphology. Here, non-degenerate pump-probe differential transmission studies with varying pump-fluence have been carried out on single-phase 2H-MoSe2 and mixed-phase 1T/2H-MoSe2 nanosheets to characterize their excited carrier dynamics. For both the samples, the differential probe transmission data show photo-induced bleaching at earlier pump-probe delay followed by photo-induced absorption unveiling signatures of exciton-state filling, exciton trapping, defect-mediated photo-induced probe absorption and recombination of defect bound excitons.

Phosphorus-Induced One-Step Synthesis of NiCoS Electrode Material for Efficient Hydrazine-Assisted Hydrogen Production.

Rational control of the reaction parameters is highly important for synthesizing active electrocatalysts. NiCoS is an excellent spinel-based electrocatalyst that is usually prepared through a two-step synthesis. Herein, a one-step hydrothermal route is reported to synthesize P-incorporated NiCoS.

Chitosan-Derived N-Doped Carbon for Light-Mediated Carbon Dioxide Fixation into Epoxides.

A series of calcined Chitosan (CS) photothermal catalysts are prepared by heating the biopolymer at different temperatures. The photothermal conversion (light to heat) ability of these calcined CS materials is evaluated by measuring the temperature change with respect to time and lamp power. The material prepared at 300 °C (Cal-CS-300) shows excellent photothermal conversion ability which is explored for the CO cycloaddition reaction with epoxides to produce cyclic carbonates under mild reaction parameters (1 atm CO pressure, 25 °C).

Sustainable Enhanced Sodium-Ion Storage at Subzero Temperature with LiF Integration.

Though layered sodium oxide materials are identified as promising cathodes in sodium-ion batteries, biphasic P3/O3 depicts improved electrochemical performance and structural stability. Herein, a coexistent P3/O3 biphasic cathode material was synthesized with "LiF" integration, verified with X-ray diffraction and Rietveld refinement analysis. Furthermore, the presence of Li and F was deduced by inductively coupled plasma-optical emission spectrometry (ICP-OES) and energy dispersive X-ray spectroscopy (EDS).

Alumina-Based Bifunctional Catalyst for Efficient CO Fixation into Epoxides at Atmospheric Pressure.

The quest toward sustainability and decarbonization demands the development of methods for efficient carbon dioxide capture and utilization. The nonreductive CO fixation into epoxides to prepare cyclic carbonates has gained attention in recent years. In this work, we report the development of guanidine hydrochloride-functionalized γ alumina (γ-AlO), prepared using green solvents, as an efficient bifunctional catalyst for CO fixation.

Ligand-Tuned Energetics for the Selective Synthesis of NiP and NiP Possessing Bifunctional Electrocatalytic Activity toward Hydrogen Evolution and Hydrazine Oxidation Reactions.

The occurrence of many phases and stoichiometries of nickel phosphides calls for the development of synthetic levers to selectively produce phases with purity. Herein, thiol (-SH) and carboxylate (-COO) functional groups in ligands were found to effectively tune the energetics of nickel phosphide phases during hydrothermal synthesis. The initial kinetic product NiP transforms into thermodynamically stable NiP at longer reaction times.

-Aminobenzoic acid-capped hematite as an efficient nanocatalyst for solvent-free CO fixation under atmospheric pressure.

Utilization of carbon dioxide by converting it into value-added chemicals is a sustainable remedy approach that stipulates abundant, cheap, non-toxic and efficient catalytic materials. In this study, we have demonstrated the use of -aminobenzoic acid-capped hematite (PABA@α-FeO) as an efficient nanocatalyst for the conversion of epoxides to cyclic carbonates utilizing CO. The developed PABA@α-FeO nanocatalyst along with a cocatalyst, tetrabutylammonium iodide (TBAI), was able to convert a variety of epoxide substrates into their corresponding cyclic carbonates under atmospheric pressure and solvent-free conditions.

Design Principle of Monoclinic NiCoSe and CoSe Nanoparticles with Opposing Intrinsic and Geometric Electrocatalytic Activity toward the OER.

Despite predictions of high electrocatalytic OER activity by selenide-rich phases, such as NiCoSe and CoSe, their synthesis through a wet-chemical route remains a challenge because of the high sensitivity of the various oxidation states of selenium to the reaction conditions. In this work, we have determined the contribution of individual reactants behind the maintenance of conducive solvothermal reaction conditions to produce phase-pure NiCoSe and CoSe from elemental selenium. The maintenance of reductive conditions throughout the reaction was found to be crucial for their synthesis, as a decrease in the reductive conditions over time was found to produce nickel/cobalt selenites as the primary product.

Ethylene glycol-mediated one-pot synthesis of Fe incorporated α-Ni(OH) nanosheets with enhanced intrinsic electrocatalytic activity and long-term stability for alkaline water oxidation.

Sustainable electrocatalytic water splitting stipulates the development of cheap, efficient and stable electrocatalysts to promote comparatively sluggish oxygen evolution reaction. We have synthesized iron-incorporated pure phase α-nickel hydroxide, Ni0.8Fe0.

Nickel-cobalt oxalate as an efficient non-precious electrocatalyst for an improved alkaline oxygen evolution reaction.

The quest for developing next-generation non-precious electrocatalysts has risen in recent times. Herein, we have designed and developed a low cost electrocatalyst by a ligand-assisted synthetic strategy in an aqueous medium. An oxalate ligand-assisted non-oxide electrocatalyst was developed by a simple wet-chemical technique for alkaline water oxidation application.

Rejuvenating the Geometric Electrocatalytic OER Performance of Crystalline Co O by Microstructure Engineering with Sulfate.

Despite significant research on its electrocatalytic OER activity, the geometric performance of Co O has remained unsatisfactory compared to relatively amorphous Co-based materials. In particular, the activity of Co O prepared through annealing always gets inferior compared to its amorphous precursor. This demands the development of synthetic techniques to prepare Co O with superior activity as the unpredictable crystal structure of the amorphous materials makes it difficult to understand their structure-activity relationships despite higher geometric activity.

Inception of CoO as Microstructural Support to Promote Alkaline Oxygen Evolution Reaction for CoSe/CoSe Network.

Developing electrocatalysts with abundant active sites is a substantial challenge to reduce the overpotential requirement for the alkaline oxygen evolution reaction (OER). In this work, we have aimed to improve the catalytic activity of cobalt selenides by growing them over the self-supported CoO microrods. Initially, CoO microrods were synthesized through annealing of an as-prepared cobalt oxalate precursor.

Highly Sensitive Upconverting Nanoplatform for Luminescent Thermometry from Ambient to Cryogenic Temperature.

Precise assessment of temperature is crucial in many physical, technological, and biological applications where optical thermometry has attracted considerable attention primarily due to fast response, contactless measurement route, and electromagnetic passivity. Rare-earth-doped thermographic phosphors that rely on ratiometric sensing are very efficient near and above room temperature. However, being dependent on the thermally-assisted migration of carriers to higher excited states, they are largely limited by the quenching of the activation mechanism at low temperatures.

Triazine-based Organic Polymer-catalysed Conversion of Epoxide to Cyclic Carbonate under Ambient CO Pressure.

In this work we have achieved epoxide to cyclic carbonate conversion using a metal-free polymeric catalyst under ambient CO pressure (1.02 atm) using a balloon setup. The triazine containing polymer (CYA-ANIS) was prepared from cyanuric chloride (CYA-Cl) and o-dianisidine (ANIS) in anhydrous DMF as solvent by refluxing under the N gas environment.

Prudent electrochemical pretreatment to promote the OER by catalytically inert "Iron incorporated metallic Ni nanowires" synthesized the "non-classical" growth mechanism.

This study provides new insight towards the non-classical "amorphous to crystalline" growth mechanism for metal nanowire synthesis and reports an electrochemical strategy to activate inactive materials into efficient electrocatalysts for the OER. Despite considerable research on transition metal oxides/hydroxides, especially NiFe based hydroxides as OER electrocatalysts, poor conductivity of these materials plagues their catalytic efficiency. In contrast, lack of catalytic centers hinders the OER performance of conductive metals.

Inception of molybdate as a "pore forming additive" to enhance the bifunctional electrocatalytic activity of nickel and cobalt based mixed hydroxides for overall water splitting.

Development of low-cost transition metal based electrocatalysts on inexpensive substrates for overall water splitting is essential to meet the future energy storage demand. In this article, we have synthesized a molybdate incorporated nickel cobalt hydroxide material on Cu mesh with nickel : cobalt : molybdenum in a 13.25 : 21.

Methylene Blue-Loaded Upconverting Hydrogel Nanocomposite: Potential Material for Near-Infrared Light-Triggered Photodynamic Therapy Application.

The property of upconverting nanoparticles to convert the low-energy near-infrared (NIR) light into high-energy visible light has made them a potential candidate for various biomedical applications including photodynamic therapy (PDT). In this work, we show how a surface functionalization approach on the nanoparticle can be used to develop a nanocomposite hydrogel which can be of potential use for the PDT application. The upconverting hydrogel nanocomposite was synthesized by reacting 10-undecenoic acid-capped Yb/Er-doped NaYF nanoparticles with the thermosensitive -isopropylacrylamide monomer.

Effect of Intrinsic Properties of Anions on the Electrocatalytic Activity of NiCoO and NiCoO S Grown by Chemical Bath Deposition.

Electrochemical water (HO) splitting is one of the most promising technologies for energy storage by hydrogen (H) generation but suffers from the requirement of high overpotential in the anodic half-reaction (oxygen evolution), which is a four-electron process. Though transition-metal oxides and oxysulfides are increasingly researched and used as oxygen evolution electrocatalysts, the bases of their differential activities are not properly understood. In this article, we have synthesized NiCoO and NiCoO S by a chemical bath deposition technique, and the latter has shown better oxygen evolution performance, both in terms of stability and activity, under alkaline conditions.

4-Mercaptobenzoic acid capped terbium(III)-doped CaF nanocrystals: a fluorescent probe for nitroaromatic pollutants.

The authors report on an energy transfer based fluorometric approach for the detection of nitroaromatic pollutants. This is achieved using 4-mercaptobenzoic acid (4-MBA)-capped CaF:Tb nanocrystals that were synthesized by a microwave procedure. 4-MBA acts as both a capping agent and a sensitizer for the Tb ions in CaF host matrix.

Classification of Transitions in Upconversion Luminescence of Lanthanides by Two-Dimensional Correlation Analysis.

Upconversion luminescence bands from Yb/Er codoped into a matrix such as NaGdF can show a very complex structure on account of multiple intra-f shell transitions occurring in the presence of random crystal fields. We demonstrate that two-dimensional correlation analysis, applied to such time-integrated luminescence spectra measured as a function of excitation power, allows us to gain substantial information about the states involved in transitions, without any additional theoretical input. The detailed correlation analysis allows us not only to identify the location of various transitions but further to club them into groups on the basis of their quantum mechanical origin, and finally subclassify the transitions with each group depending on whether they have a common initial or final state.

Design of Lanthanide-Doped Colloidal Nanocrystals: Applications as Phosphors, Sensors, and Photocatalysts.

The unique optical characteristics of lanthanides (Ln) such as high color purity, long excited-state lifetimes, less perturbation of excited states by the crystal field environment, and the easy spectral conversion of wavelengths through upconversion and downconversion processes have caught the attention of many scientists in the recent past. To broaden the scope of using these properties, it is important to make suitable Ln-doped materials, particularly in colloidal forms. In this feature article, we discuss the different synthesis strategies for making Ln-doped nanoparticles in colloidal forms, particularly ways of functionalizing hydrophobic surfaces to hydrophilic surfaces to enhance their dispersibility and luminescence in aqueous media.

Ce -Sensitized Tm /Mn -Doped NaYF Colloidal Nanocrystals: Intense Cool White Light from a Phosphor-Coated UV LED.

Colloidal NaYF :Ce /Tm /Mn nanocrystals found to be an efficient single component phosphor to produce intense white light. The use of Mn ions instead of green- and red-emitting Ln ions is interesting as the later are expensive and less abundant. The single band blue emission of Tm ions was combined with the broadband green-yellow emission of Mn ions to produce strong white light emission using Ce ions as excitation source.