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Transition metal phosphides (TMPs) are expected to be excellent electrocatalysts for oxygen evolution reaction (OER) because of their high stability, highly conducting metalloid nature, highly abundant constituting elements, and the ability to act as a precatalyst due to

Cellulose-fiber extracted from biomass waste by a simple method is used as a template for bimetallic Pd-Ag nanoclusters that exhibited photocatalytic proficiency in Suzuki-Miyaura cross-coupling of nitrogen heterocycles at room-temperature.

MCO-MnO2-PC||PC as a high-performance flexible asymmetric supercapacitor device.

An efficient methodology for the direct decarboxylative functionalization of cinnamic acid derivatives with cyclic ethers has been developed by using biogenic CuO/C nanoparticles. This protocol is compatible with broad range of substrates.

The use of FeCoPd alloy nanoparticles as a promising bifunctional electrocatalyst for hydrogen and oxygen evolution reaction is demonstrated. DFT calculations further validate the proposed high efficiency mechanism corroborating with experimental results.

International audience; Over the last decade, artificial enzymes (nanozymes) have undergone substantial development in the field of sensing. In this study, Au−Ag bimetallic nanoparticles (NPs) decorated on reduced graphene oxide sheets (AuAg-rGO) nanocomposite has been developed as a novel colorimetric probe based on the peroxidase imitating activity of the nanozyme. AuAg-rGO nanocomposite proved to feature an intrinsic peroxidase mimic activity, facilitating the oxidation of a peroxidase substrate like 3,3’,5,5’-tetramethylbenzidine (TMB) with high efficiency to oxidised TMB (blue coloured product) with the aid of hydrogen peroxide (H2O2). The characteristic Michaelis-Menten kinetics study allowed the establishment of the catalytic performance of AuAg-rGO as an artificial enzyme. Glutathione (GSH) displays inhibiting effect on the oxidation of the peroxidase substrate, TMB. Therefore, AuAg-rGO nanozyme was applied for detection of GSH and exhibited exceptional selectivity and sensitivity with a low limit of detection (LOD) of 38 nM within the 0–200 μM concentration range. The artificial nanozyme system reported here is simple, convenient, and straightforward for colorimetric sensing of GSH.

Herein, a flexible high-performance supercapacitor cell using nanostructured CuCo-layered double hydroxide (LDH) as power source electrode material is reported for the first time, where the CuCo-LD...

International audience; Efficient electrochemical splitting of water with exceptional durability can be a solution for growing global demand for energy. Herein, we systematically investigated the influence of the supporting two-dimensional (2D) substrate (rGO, g-C3N4, BCN, MoS2, and WS2) on the electrocatalytic performance of CoS2 nanoparticles (NPs) for overall water splitting. CoS2NPs decorated onto rGO, g-C3N4, BCN, MoS2, and WS2 sheets were synthesized by adopting a facile hydrothermal technique using cobalt salt and sulfur source as precursors. Compared to unsupported CoS2, the synthesized nanohybrids supported on 2D materials, namely, CoS2/rGO, CoS2/g-C3N4, CoS2/BCN, CoS2/MoS2, and CoS2/WS2 exhibited significantly higher water oxidation and reduction and overall water splitting efficiencies in 1.0 M KOH aqueous solution, with CoS2/MoS2 and CoS2/WS2 catalysts being the most effective ones. In the case of the hydrogen evolution reaction (HER), CoS2/WS2 performed as the best catalyst and was able to provide a current density of 10 mA cm-2 at an overpotential of 130 mV, whereas it only required 298 mV to generate the same current density for the oxygen evolution reaction (OER). The bifunctional nanohybrid CoS2/WS2 catalyst achieved a current density of 10 mA cm-2 over 96 h for the alkaline overall water splitting at a cell voltage of 1.6 V. Density functional theory (DFT) calculations were also performed to further describe and determine the HER catalytic performance of the studied catalysts. Comparing the absolute values of the studied catalysts' Gibbs free energy of adsorbed hydrogen intermediate, H∗, (GH∗), revealed that both CoS2/MoS2 and CoS2/WS2 hybrid catalysts exhibited the best surface stability and the highest HER catalytic performance.

Distorted honeycomb-like hollow cage-structured bio-nanocellulose (with 1–16.7 μm diameters) is derived from cellulosic waste of pomegranate peel using a simple microwave technique in water under n...

Fe3O4-SiO2 microspheres were synthesized by a three-step synthetic procedure involving silica coating, surface capping, and surface modification. These magnetic mesoporous microspheres were employed as sorbents for the incorporation of ultrasmall Ru nanoparticles (2-5 nm) followed by thermal aggregation of the microspheres for achieving better heterogeneity and low leaching. The Ru decorated Fe3O4-SiO2 microspheres (Ru@Fe3O4-CSM) were applied as chemoselective catalysts to convert more than 20 substituted nitroarenes to corresponding amines with good-to-excellent conversion (77-99%) and selectivity (70-100%) under mild conditions; the catalyst can be magnetically recovered within a frame of 90s (recovery time-lapse) and reused up to 5 times without significant decrease in activity or selectivity. Magnetic hysteresis studies were performed to elucidate the magnetic behavior of the ruthenium decorated materials.

In this work, a colorimetric approach for the detection of ascorbic acid (AA) and thyroxine (TH) was developed by synthesizing cost-effective silver nanoparticles (AgNPs) decorated with epigallocatechin gallate (EGCG) and CTAB. EGCG is the major bioactive chemical constituent that played a significant role in this study. The environment around the nanoparticle (NP) was controlled by adding CTAB surfactants. The synthesized NPs were characterized by different advanced techniques including XRD, XPS, SEM, and TEM. UV-visible spectra were thoroughly analyzed for sensing of AA and TH and the colour change of the solution can be visually monitored. The change in the localized surface plasmon resonance (LSPR) properties was used as an asset for the detection of AA and TH. A good linear relationship was obtained in both the sensing schemes with a limit of detection (LoD) of 0.67 μM and 0.33 μM for AA and TH respectively. Furthermore, the nanoparticles (NP) were implemented for real-sample analysis (pharmaceutical tablets). A cost-effective filter paper strip-based method coupled with smartphone scanning sensing was developed for the detection of AA. The interaction of AA and TH with the probe was depicted by a density functional theory (DFT) analysis. The synthesized NPs show tremendous selectivity towards AA and TH and excellent potential for practical applications.

Hydrogen peroxide (H2O2) has tremendous applications in industry, medicine and in our day-to-day lives. It is toxic to human health upon exposure at a high concentration. Therefore, a green and cost-effective sensing technique is greatly needed for the sensitive naked eye detection of peroxide. This study is mainly focused on the synthesis of Au nanoparticles (AuNPs) using an aqueous extract of Elsholtzia blanda, a flower that is widely available in the North Eastern part of India, the characterization of which was carried out using different analytical techniques. The bioactive molecule (epigallocatechin gallate) present in the aqueous extract was identified, isolated and confirmed through high-performance liquid chromatography-photodiode array, high-resolution mass spectrometry and nuclear magnetic resonance spectroscopy analysis which could be responsible for the reduction of Au3+ ions. By approaching this greener route, the synthesized nanomaterial was further used as a colorimetric probe for the detection of H2O2 and the degradation of AuNPs was observed. The limit of detection was found to be 0.7435 μM in the present work. The degradation of the AuNPs was found to be linearly dependent on peroxide concentration. Along with these results, kinetic studies were carried out by considering different effects to monitor the sensing speed of the AuNPs. The plausible mechanism of the work was supported by density functional theory study.

Application of an alliin-based precursor for the synthesis of silver nanoparticles (Ag NPs) which is an emerging, reliable and rapid sensor of heavy metal ion contaminants in water is reported here. The Ag NPs were characterized by using UV-visible spectroscopy, X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy and Raman spectroscopy analysis techniques. The Ag NPs simultaneously and selectively detect Hg2+ and Sn2+ ions from aqueous solution. The sensitivity and selectivity of the prepared Ag NPs towards other representative transition-metal ions, alkali metal ions and alkaline earth metal ions were also studied. For more precise evidence, a density functional theory study was carried out to understand the possible mechanism and interaction in the detection of Hg2+ and Sn2+ by Ag NPs. The limits of detection for Hg2+ and Sn2+ ions were found as 15.7 nM and 11.25 nM, respectively. This assay indicates the possible use of garlic extract-synthesized Ag NPs for sensing Hg2+ and Sn2+ in aqueous solution very significantly. So, the simple, green, eco-friendly and easy method to detect the dual metal ions may further lead to a potential sensor of heavy metal ion contaminants in water of industrial importance.

The development of cost effective and efficient nanomaterials with enzyme mimetics and photocatalytic activity has achieved tremendous research interest in the quantitative detection as well as removal of toxic environmental pollutants. CuS nanoparticles decorated MoS2 sheets were successfully synthesized adopting a simple hydrothermal technique and using low-cost materials. The nanocomposite was successfully used as an efficient catalyst for the selective detection and removal of a toxic phenolic compound like hydroquinone (HQ). The CuS–MoS2 nanocomposite catalyzed the oxidation of different chromogenic substrates like 3,3′,5,5′-tetramethylbenzidine, 2,2′-azino-bis(3-ethylbenzo-thiazoline-6-sulfonic acid)diammonium salt, and o-phenylenediamine in the presence of H2O2, indicating its peroxidase-like activity as natural Horseradish peroxidase (HRP). The catalytic performance of the nanozyme was further investigated through the typical Michaelis−Menten kinetics. The results showed that the proposed sensor exhibited improved catalytic properties with a wide linear relationship (0.4–50 μM) and a low detection limit of 3.68 μM for HQ detection in aqueous medium. Meanwhile, the mechanism of HQ sensing in the presence of CuS–MoS2 nanozyme was systematically investigated. Moreover, the CuS–MoS2 nanozyme possessed significant photocatalytic activity and 83% HQ decomposition was achieved within 240 min under irradiation of natural sunlight. The mechanism of enhanced photocatalytic degradation of HQ through the formation of ˙OH radicals as reactive species was evidenced by analyzing the formation of fluorescent active molecules on the addition of terephthalic acid and by high-resolution mass spectrometry. Thus CuS–MoS2 represents a new and promising HQ sensing material in a highly sensitive and fast manner as well as an efficient photocatalyst for the degradation of HQ to its non-toxic products under natural sunlight irradiation.

International audience; A new bipyridine-containing manganese (II) complex, namely [(BPy)2MnCl2]·0.5H2O (MnC), was synthesized and characterized. Spectral and X-ray structural features revealed that MnC has an octahedral environment around Mn(II). Graphene oxide (GO) was noncovalently functionalized with the MnC. MnC- and (MnC/GO)-modified glassy carbon (GC) interfaces with different loading densities (0.2, 0.4, 0.8, and 1.0 mg cm−2) were tested as electrocatalysts for efficient generation of H2 in 0.1 M KOH solution. The GC-MnC catalysts exhibited high electrocatalytic activity for the HER, which enhances upon increasing the catalyst's loading density. The GC-MnC catalyst's HER activity, at any tested loading density, was found to further increase upon supporting MnC on GO. The best performing electrocatalyst, namely GC-(MnC/GO) with a loading density of 1.0 mg cm−2, exhibited high HER catalytic activity with a low onset potential value of −22 mV vs. reference hydrogen electrode (RHE) and a high exchange current density of 0.75 mA cm−2. It delivered a current density of 10 mA cm−2 at an overpotential value of 119 mV. In addition, it recorded a Tafel slope value of −114 mV dec−1. These HER electrochemical kinetic parameters approached those measured here for the commercial Pt/C under the same operating conditions (−10 mV vs. RHE, 0.88 mA cm−2, 113 mV dec−1, and 110 mV to yield a current density of 10 mA cm−2) and also comparable to the most active molecular electrocatalysts for H2 generation from aqueous alkaline electrolytes published in the literature. The long-term stability of the best performing electrocatalyst, namely GC-MnC (1.0 mg cm−2)/GO, was evaluated using cyclic voltammetry (repetitive cycling up to 5000 cycles) and chronoamperometry (48 hours) techniques, and the obtained results revealed its promising stability. A plausible mechanism for the interaction of MnC with GO was proposed based on density functional theory (DFT) calculations. DFT calculations confirmed the catalytic role of the supporting material (GO) on the fabricated metal complex in catalyzing the HER.

International audience; In this work, we report on enhanced adsorption of anionic dyes, Reactive blue 49 (RB 49) and Direct Blue 199 (DB 199), using a phytic acid-doped poly-N-phenylglycine@potato peel (PA-PPG@PP) nanocomposite material. The PA-PPG@PP was prepared using a radical polymerization process by varying the amount of potato peel powder (PP) in the composite material. The surface structure and composition were examined by zeta potential, scanning electron microscopy (SEM), Fourier-transform infrared (FTIR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and Brunauer–Emmett–Teller (BET) analysis. The influence of different operating conditions such as adsorbent dose, initial dye concentration, contact time, pH and ionic strength on the removal efficiency of PA-PPG@PP2 was assessed to achieve the optimum conditions for RB 49 dye adsorption. Adsorption equilibrium data were well-described by the Langmuir model and the maximum adsorption capacities of PA-PPG@PP2 for RB 49 and DB 199 at 298 K and pH = 6.5 were 216 and 1148 mg g−1, respectively. The maximum adsorption capacity of RB 49 dye on the PA-PPG@PP2 surface was achieved at 318 K (285 mg g−1). The adsorption process was described by the pseudo-second-order kinetics model (R2 > 0.999). The thermodynamic study proved that the adsorption processes were endothermic and favorable. The dye molecules were adsorbed on the composite material surface mainly through hydrophobic and electrostatic interactions, as well as hydrogen bonding. Additionally, our experimental results suggested that the hydrophobic interactions increased upon increasing ionic strength, while the electrostatic interactions decreased upon elevating the ionic strength of the solution. The findings in this work revealed the potential of biomass powder, potato peels, in adsorption processes upon hybridization with a biocompatible organic polymer, poly-N-phenylglycine.

It is well known that the benchmark electrocatalysts for OER in alkaline solution are RuO2 and IrO2; however, the high cost, scarcity, and instability of these metal oxides impede their ample use in OER processes, and this has fuelled the search for cheap Earth-abundant elements which are equally efficient for application as electrocatalysts in OER. The present work reports the use of hydrothermal and calcination methods for the synthesis of nanocomposites made up of Ni and/or Co salts and urea in combination with MoSe2 and MoS2 and their application as efficient and stable electrocatalysts for OER in alkaline solution. The NiCoMoSe, NiCoMo, CoMoSeS, and CoMo nanocomposites constructed in the present study presented high OER electrocatalytic activity and stability mainly as a result of the following: the combination of N atoms bonded to Ni and/or Co (and Mo); the electrons released from the oxidation of Co from the 2+ to 3+ state, Ni oxidation from the 2+ to 3+ state, and Mo oxidation from the 4+ to 6+ state; and the metal oxides (CoMoO4, NiCo2O4, Co2Mo3O8, and Co3O4) supported on MoS2 nanosheets and MoSe2 nanoribbons which contributed to a decrease in charge transfer resistance, apart from keeping the ECSA values relatively low.

The excellent cyclic efficiency, superior reversible charge/discharge rate, and high specific power density have made supercapacitors an important class of energy storage systems in recent time. In this study, two nano-ceria-based composites were developed to use as electrode materials in supercapacitor applications. The composites were synthesized by combining ceria with conductive polyaniline (PANI) and doped with HCl and p-toluene sulfonic acid (PTSA). The materials were characterized by FTIR spectroscopy, SEM, XRD, and XPS techniques. Electrochemical studies were performed by cyclic voltammetry, galvanometric charge-discharge, and AC impedance spectroscopy. The CeO2-PANI doped with HCl and PTSA composites displayed ideal supercapacitor behavior showing higher capacitances up to 504 F g−1 and 454 F g−1, respectively, at current density of 1 A g−1 in comparison with pristine ceria (109 F g−1). Both the composites exhibited excellent specific energy (up to 100.8 W h kg−1) as well as outstanding specific power (up to 830 W kg−1). These findings support the possibility of these composites for practical applicability as electrode materials in energy storage devices.

Multifunctional materials are quite fascinating and conveniently serve the purpose where two or more efficient materials are required. Herein, we report such a bifunctional material which is new by...

Direct C(sp2)–H bond functionalization of indoles with arylboronic acids is achieved using palladium supported on carbon as a reusable heterogeneous catalyst in the presence of an oxidant under mild conditions. The current protocol formed exclusive C-2 selective products without the aid of any ligand or directing group. The catalyst is reusable for up to four catalytic cycles with the retention of catalytic efficiency.

‘On-water’ synthesis of 2,2-bis(indoly-3-yl)indoline-3-ones via N2-selective dearomatization of ‘(N–H) protection-free’ indole derivatives is described. An oxidative homo trimerization of indole via nano Au/Pd catalysis with oxone as additive was successfully demonstrated for the first time. In situ generation of isatin at room temperature and with water as solvent are key features.

The energy demand, the crisis of fossil fuels, and the increasing popularity of portable and wearable electronics in the global market have triggered the demand to develop high-performance flexible all-solid-state supercapacitors that are capable of delivering high energy at high power density as well as being safely entrenched in those electronics. Herein, we have designed a nanocomposite, 80CF