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Magnetically integrated ultrathin h-BN nanosheets based nickel catalyst for the one-pot multicomponent reaction to access 1,4-dihydropyridines.

Advanced materials comprising biowaste, and nature-inspired (nano)materials having unique properties have been highlighted. Critical discussion of their efficiency on the fuel cell output has been provided.

Magnetic two-dimensional boron nitride nanosheet-based copper catalyst has been synthesized for accessing a wide array of 2-amino-4-aryl(or heteroaryl)-7,7-dimethyl-5-oxo-5,6,7,8-tetrahydro-4H-chromene-3-carbonitriles.

This review aims to explore the design, development and applications of magnetically supported covalent organic frameworks (MCOFs) in extraction of metal ions, nitro explosives and chemical pollutants.

A noble metal free heterogeneous cobalt based photocatalyst was designed to carry out visible light mediated direct (het)arene C–H arylation and CO2 capture.

A comprehensive review of the synthesis and applications of Cu and Cu-based nanomaterials. A variety of applications including organic reactions, photocatalysis, environmental remediation, and sensors have been included.

A straightforward and mild protocol for photochemical in situ selective hydrogenation is described via an Al–H2O system as a hydrogen donor and deploying a Pd-g-C3N4 photocatalyst under visible light and ambient conditions.

The report presents the fabrication and application of a highly versatile, magnetic and robust iridium based photoredox nanocatalyst. Herein, Ir(PPy)3 based photocatalyst sites have been chemically engineered over the magnetic nanoparticles to encompass the captivating features of homogeneous iridium photocatalyst with the magnetically recyclable core. A household photoreactor was designed and fabricated to achieve highly selective visible light driven oxidative C-H arylation and C-H cyanation under sustainable and ambient reaction conditions utilizing the Ir@PyBz@ASMNPs photoredox nanocatalyst. The environment friendly Ir@PyBz@ASMNPs shows excellent photocatalytic activity, broad substrate adaptability and outstanding recyclability compared to the analogous homogeneous catalysts. Indeed, the Ir@PyBz@ASMNPs possess some key features including high surface area, high iridium metal loading and excellent stability. This work is expected to enlighten and provide new insights in the rational design of high performance and recoverable photoredox nanocatalyst through surface engineering strategy.

This research discusses the CO

Inorganic electrides have been proved to be efficient hosts for incorporating transition metals, which can effectively act as active sites giving an outstanding catalytic performance. Here, it is demonstrated that a reusable and recyclable (for more than 7 times) copper-based intermetallic electride catalyst (LaCu

Flexible electronic devices entail highly transparent and conducting electrodes with excellent adherent and mechanically robust properties along with excellent bendability. Here, we report the development of transparent and conducting electrodes comprising silver nanowires (AgNWs) and amorphous-titanium oxide (a-TiOx) nanocomposite thin films. The AgNWs and a-TiOx nanocomposite thin films were deposited by a wire bar coating process, a scalable and high throughput procedure. PXRD analysis confirmed the crystalline and amorphous nature for AgNWs and TiOx thin film, respectively. FE-SEM and HRTEM analyses revealed the core–shell nature of the composite where AgNWs and a-TiOx acted as core and shell, respectively. Even after three-layer coating of AgNWs-a-TiOx nanocomposite thin films, high transparency (~ 77%) in the visible region (400–800 nm) and a sheet resistance of 23 Ω/sq were observed. Furthermore, tape peel off tests were conducted for AgNWs and AgNWs-a-TiOx nanocomposite, which displayed high adherence for the three-layer coated AgNWs-a-TiOx nanocomposite as compared with AgNWs alone. The formation of AgNWs-a-TiOx core–shell structure enhances the intra-particle binding and network formation of AgNWs. The preliminary studies highlight that the developed AgNWs-a-TiOx nanocomposite thin films have great potential as transparent electrodes for realizing scalable cost-effective flexible electronic devices.

In view of their unique characteristics and properties, silver nanomaterials (Ag NMs) have been used not only in the field of nanomedicine but also for diverse advanced catalytic technologies. In this comprehensive review, light is shed on general synthetic approaches encompassing chemical reduction, sonochemical, microwave, and thermal treatment among the preparative methods for the syntheses of Ag-based NMs and their catalytic applications. Additionally, some of the latest innovative approaches such as continuous flow integrated with MW and other benign approaches have been emphasized that ultimately pave the way for sustainability. Moreover, the potential applications of emerging Ag NMs, including sub nanomaterials and single atoms, in the field of liquid-phase catalysis, photocatalysis, and electrocatalysis as well as a positive role of Ag NMs in catalytic reactions are meticulously summarized. The scientific interest in the synthesis and applications of Ag NMs lies in the integrated benefits of their catalytic activity, selectivity, stability, and recovery. Therefore, the rise and journey of Ag NM-based catalysts will inspire a new generation of chemists to tailor and design robust catalysts that can effectively tackle major environmental challenges and help to replace noble metals in advanced catalytic applications. This overview concludes by providing future perspectives on the research into Ag NMs in the arena of electrocatalysis and photocatalysis.

With the advancements in materials engineering, unprecedented newer materials based on magnetic MOFs have emerged as one of the promising candidates in the strategic field of catalysis. Within this perspective, the present report unveils the fabrication of an intricately designed magnetic CoFe2O4/Ni-BTC based MOF composite via a one-pot solvothermal approach. The synthesized composite was comprehensively characterized using various analytical tools such as FTIR, XRD, XPS, VSM, TGA, EDS, ED-XRF and AAS. Advanced microscopic tools like SEM and TEM provided deep insights into the structural aspects of the synthesized material. The catalytic performance of the hybrid composite was further explored in one-pot multicomponent reactions to obtain a combinatorial library of biologically and pharmacologically significant 2,4,5-trisubstituted (up to 98% yield) and 1,2,4,5-tetrasubstituted (up to 97% yield) imidazoles in good to excellent yields under solvent free conditions. Wider functional group tolerance, excellent turnover numbers, high atom economy, ambient reaction conditions, magnetic retrievability and good recyclability are some of the striking attributes of this protocol. We envisage that the present methodology employing magnetic MOFs as catalytic reactors is highly desirable for designing cleaner and greener processes in modern organic chemistry.

The emergence of carbon quantum dots (CQDs) opens up new opportunities in different branches of science and technology primarily because of their conducive biocompatibility, tunable bandgaps, and u...

Silica materials are used in a wide range of applications such as catalysis, photocatalysis, CO2 capture, and environmental remediation. These nanomaterials (NMs) have been extensively investigated...

A new P- and F-co-doped amorphous carbon nitride (PFCN) has been synthesized via sol-gel-mediated thermal condensation of dicyandiamide. Such synthesized P- and F-co-doped carbon nitride displayed a well-defined mesoporous nanostructure and enhanced visible light absorption region up to infrared with higher BET surface area of 260.93 m2 g-1 ; the highest recorded value for phosphorus-doped carbon nitride materials. Moreover, the formation mechanism is delineated and the role of templates was found to be essential not only in increasing the surface area but also in facilitating the co-doping of P and F atoms. Co-doping helped to narrow the optical band gap to 1.8 eV, thus enabling an excellent photocatalytic activity for the aqueous reduction of carbon dioxide into methanol under visible-light irradiation, which is fifteen times higher (119.56 μmol g-1 h-1 ) than the bare carbon nitride. P doping introduced Bronsted acidity into the material, turning it into an acid-base bifunctional catalyst. Consequently, the material was also investigated for the thermal conversion of common carbohydrates into furanics.

The utilization of non-noble metals for the design of advanced catalysts is gaining importance from an environmental sustainability viewpoint. A variety of non-noble metal nanoparticles decorated o...

Nanoscale zerovalent iron (nZVI) particles represent an important material for diverse environmental applications because of their exceptional electron-donating properties, which can be exploited for applications such as reduction, catalysis, adsorption, and degradation of a broad range of pollutants. The synthesis and assembly of nZVI by using biological and natural sustainable resources is an attractive option for alleviating environmental contamination worldwide. In this Review, various green synthesis pathways for generating nZVI particles are summarized and compared with conventional chemical and physical methods. In addition to describing the latest environmentally benign methods for the synthesis of nZVI, their properties and interactions with diverse biomolecules are discussed, especially in the context of environmental remediation and catalysis. Future prospects in the field are also considered.

Carbon-based materials are widely employed as metal-free catalysts or supports in catalysis, energy, and ecological applications because of their interesting properties. Generally, their high surface areas, size, shape, porosity, and the possibility of incorporating additional moieties through chemical functional designs are believed to be essential for enriching the catalytic activity of carbon-containing materials. Lately, the new field of single-atom catalysts (SACs) has emerged as the finest alternative for not only homogeneous but also heterogeneous catalysts used in various kinds of catalytic applications. Among a variety of SACs, carbon-based SACs are widely investigated catalysts because of their extraordinary features such as tunable morphologies, ordered porosity, and effortless immobilization through various metals (noble and non-noble), making them highly efficient single-atom catalysts for numerous important catalytic applications. Herein, we intend to report on the progress achieved in researching carbon-based single-atom catalysts, including primarily metals such as Co, Cu, Zn, Pd, Ni, Pt, among others, embedded in carbon matrices and applied to applications in organic catalysis, photocatalysis, and electrocatalysis. It is important to point out that the main focus of this Review is directed to the activity and applications of single-atom catalysts, which are discussed in detail; thus, characterization and rationalization are excluded. Finally, we provide a future perspective on the development and progress made on a carbon-based single metal atom for catalysis.

The vital need for an external dehydrating agent in high-yield production of dimethyl carbonate (DMC) has been circumvented via in situ formation of copper sulfide (Cu2S) bonded 2D-sulfonated organic polymers, Cu-SOPm and Cu-SOPs, by deploying single-step and solvent-assisted mechanochemical and solvothermal methods, respectively. Cu-SOPm exhibited excellent catalytic activity for the continuous production of DMC from carbon dioxide and methanol without using a dehydrating agent. The presence of a higher amount of sulfonic acid groups (–SO3H) is the key factor, which can adsorb the ensuing water during the reaction thus shifting reaction equilibrium in the forward direction; Cu-SOPs is relatively less active catalytically owing to a smaller amount of sulfonic groups. All the reactions are accomplished on a high-pressure fixed-bed flow reactor and the effects of various reaction parameters (flow rate, catalyst amount, system temperature and pressure) are investigated, especially the preheating of the CO2 and CH3OH mixture, which facilitated methanol conversion considerably, and afforded 42.8% yield of DMC with 100% selectivity. The preparation of the catalysts and formation of DMC were supported by a plausible mechanism wherein increased residence time and high reaction pressure always favored the methanol conversion. This study enables the continuous high-yield generation of DMC under flow conditions deploying preheating of substrates and concomitantly addressing the lingering problem for designing a built-in dehydrating capability in the catalyst.

Lignocellulosic biomass is becoming a viable alternative or complementary source for obtaining petroleum-derived products such as fuels, polymers and fine chemicals, among others. Nevertheless, the successful upgrading of lignocellulosics requires the design of efficient and robust catalysts, where sulfonated mesoporous silica materials may be an ideal choice for exploration. Herein, we have conducted the upgrading of several mono-, di- and polysaccharides such as xylose, fructose, glucose, sucrose and cellulose to valuable platform chemicals using a novel catalyst comprising sulfonated dendritic mesoporous silica nanospheres. Additionally, a thorough comparative study was conducted encompassing arrays of sulfonated silicas as catalysts with the aim of relating their activities and appreciating the features which could be responsible for their activity.

We report the synthesis of in situ generated cobalt nanoparticles from molecularly defined complexes as efficient and selective catalysts for reductive amination reactions. In the presence of ammonia and hydrogen, cobalt–salen complexes such as cobalt(ii)–N,N′-bis(salicylidene)-1,2-phenylenediamine produce ultra-small (2–4 nm) cobalt-nanoparticles embedded in a carbon–nitrogen framework. The resulting materials constitute stable, reusable and magnetically separable catalysts, which enable the synthesis of linear and branched benzylic, heterocyclic and aliphatic primary amines from carbonyl compounds and ammonia. The isolated nanoparticles also represent excellent catalysts for the synthesis of primary, secondary as well as tertiary amines including biologically relevant N-methyl amines., We report the synthesis of in situ generated cobalt nanoparticles from molecularly defined complexes as efficient and selective catalysts for reductive amination reactions.

Covalent organic frameworks (COFs) are one of the most important and dynamic members of the porous organic materials and are constructed using reticular chemistry with the building blocks being connected via covalent bonds. Due to their fascinating properties such as large surface area; structural versatility; effortless surface modification; and high chemical stability, COFs are being widely deployed in catalytic; sensing; adsorption; gas storage; and many other valuable applications. This review summarizes selected and most recent espoused synthetic methodologies for their assembly including the formation of magnetic COFs. Potential insights in the field of catalysis; electrocatalysis; and photocatalysis, where COFs can serve as excellent platforms for supporting catalytic species, are also illustrated.

In this study, a facile method for the synthesis of leach proof and earth-abundant non-noble Ni nanoparticles on N-doped carbon nanotubes is reported. The catalyst was synthesized by an impregnation-carbonization method, wherein a Ni-chitosan complex upon carbonization in a 5% H2/N2 atmosphere at 800 °C yielded Ni-containing N-doped CNTs. Chitosan served as a single source of carbon and nitrogen, and the nanotube growth was facilitated by the in situ formed Ni nanoparticles. The nanocatalyst was thoroughly characterized by several techniques; elemental mapping by SEM and TEM analysis confirmed the uniform distribution of Ni nanoparticles on the surface of N-doped CNTs with an average size in the range of 10-15 nm. The catalyst efficiently reduced a variety of nitroarenes (>99%) into their corresponding amines at a moderate pressure (5 bar) and a comparatively lower temperature (80 °C). Furthermore, the easy recovery of the catalyst using an external magnetic field along with high activity and easy recyclability makes the protocol eco-friendly.

This research discusses the CO2 valorization via hydrogenation over the non-noble metal dusters of Ni and Cu supported on graphitic carbon nitride (g-C3N4). The Ni and Cu catalysts were characterized by conventional techniques including XRD, AFM, ATR, Raman imaging, and TPR and were tested via the hydrogenation of CO2 at 1 bar. The transition-metal-based catalyst designed with atom-economy principles presents stable activity and good conversions for the studied processes. At 1 bar, the rise in operating temperature during CO2 hydrogenation increases the CO(2 )conversion and the selectivity for CO and decreases the selectivity for methanol on Cu/CN catalysts. For the Ni/CN catalyst, the selectivity to light hydrocarbons, such as CH4, also increased with rising temperature. At 623 K, the conversion attained ca. 20%, with CH4 being the primary product of the reaction (CH4 yield >80%). Above 700 K, the Ni/CN activity increases, reaching almost equilibrium values, although the Ni loading in Ni/CN is lower by more than 90% compared to the reference NiREF catalyst. The presented data offer a better understanding of the effect of the transition metals' small metal cluster and their coordination and stabilization within g-C3N4, contributing to the rational hybrid catalyst design with a less-toxic impact on the environment and health. Bare g-C3N4 is shown as a good support candidate for atom-economy-designed catalysts for hydrogenation application. In addition, cytotoxicity to the keratinocyte human HaCaT cell line revealed that low concentrations of catalysts particles (to 6.25 mu g mL(-1)) did not cause degenerative changes. Web of Science

Hydrazine oxidation in single-atom catalysts (SACs) could exploit the efficiency of metal atom utilization, which is a substitution for noble metal-based electrolysers that results in reduced overall cost. A well-established ruthenium single atom over mesoporous carbon nitride (SRu-mC(3)N(4)) catalyst is explored for the electro-oxidation of hydrazine as one of the model reactions for direct fuel cell reactions. The electrochemical activity observed with linear sweep voltammetry (LSV) confirmed that SRu-mC(3)N(4) shows an ultra-low onset potential of 0.88 V vs. RHE, and with a current density of 10 mA/cm(2) the observed potential was 1.19 V vs. RHE, compared with mesoporous carbon nitride (mC(3)N(4)) (1.77 V vs. RHE). Electrochemical impedance spectroscopy (EIS) and chronoamperometry (i-t) studies on SRu-mC(3)N(4) show a smaller charge-transfer resistance (R-Ct) of 2950 omega and long-term potential, as well as current stability of 50 h and 20 mA/cm(2), respectively. Herein, an efficient and enhanced activity toward HzOR was demonstrated on SRu-mC(3)N(4) from its synergistic platform over highly porous C3N4, possessing large and independent active sites, and improving the subsequent large-scale reaction. Web of Science 12 12 art. no. 1560

Constantly increasing hydrocarbon fuel combustion along with high levels of carbon dioxide emissions has given rise to a global energy crisis and environmental alterations. Photocatalysis is an effective technique for addressing this energy and environmental crisis. Clean and renewable solar energy is a very favourable path for photocatalytic CO2 reduction to value-added products to tackle problems of energy and the environment. The synthesis of various products such as CH4, CH3OH, CO, EtOH, etc., has been expanded through the photocatalytic reduction of CO2. Among these products, methanol is one of the most important and highly versatile chemicals widely used in industry and in day-to-day life. This review emphasizes the recent progress of photocatalytic CO2 hydrogenation to CH3OH. In particular, Metal organic frameworks (MOFs), mixed-metal oxide, carbon, TiO2 and plasmonic-based nanomaterials are discussed for the photocatalytic reduction of CO2 to methanol. Finally, a summary and perspectives on this emerging field are provided.

As a group of large-surface-area nonmetal materials, polymeric carbon nitride (CxNy) and its hybrid structures are nowadays of ever-increasing interest for use in energy devices involved in energy conversion and storage, offering low expenses and facile production processes. With the growing requirement for clean and renewable energy generation and storage systems, progress in the replacement of expensive noble-metal catalysts with CxNy-based materials as efficient electrocatalysts has expanded considerably, and the demand for these materials has increased. The modified CxNy architectures are beneficial to electrocatalytic applications, improving their moderate electrical conductivities and capacity loss. The present review strives to highlight the recent advances in the research on the aforementioned identities of CxNy-derived materials and their structurally modified polymorphs. This review also discusses the use of CxNy-based materials in fuel cells, metal-air batteries, water splitting cells, and supercapacitor applications. Herein, we deal with electrocatalytic oxidation and reduction reactions such as hydrogen evolution, oxygen evolution, oxygen reduction, CO2 reduction, nitrogen reduction, etc. Each device has been studied for a clearer understanding of the patent applications, and the relevant experiments are reviewed separately. Additionally, the role of CxNy-derived materials in some general redox reactions capable of being exploited in any of the relevant devices is included.

The field of 2-dimensional (2D) materials has witnessed a sharp growth since its inception and can majorly be attributed to the substantial technical and scientific developments, leading to significant improvements in their syntheses, characterization and applications. In the list of 2D materials, the relatively newer addition is phosphorene, which ideally consists of a single layer of black phosphorous. Keeping in mind the past, and ongoing research activities, this short account offers a brief overview of the present status and the associated challenges in the field of phosphorene-related research, with special emphasis on their syntheses, properties, applications and future opportunities.

Ni, Cu and Cu–Ni nanostructures have been fabricated and homogeneously embedded on ultrathin two-dimensional (2D) carbon nitride (g-C3N4), and the surface morphology and composition of the resulting hybrid nanostructures were studied by XRD, TEM, HRTEM-elemental mapping, Raman spectroscopy and XPS. The new hierarchical hetero-structures dropcasted on GC anodes have been visualised by SEM and their catalytic performance have been examined in methanol electrooxidation reaction (MOR) under alkaline conditions. Nanosized Ni particles dispersed finely over g-C3N4 are very active electrocatalysts with MOR onset at potential 0.35 V and charge transfer resistance 0.12 kΩ. The stability of modyfied GC electrodes, examined under chronoamperometric conditions showed that for electrode loading with 4% (wt. %) of NiO the stable current density ca. 36 A g−1 (12 A cm2) was obtained during whole experiment (up to 160 min). For all catalyst studied the curent density obtained during MOR reaction was enhanced when electrode was iluminated by UV light λ∼400 nm, and the highest value were obtained for 4% Ni/CN catalyst ca. 127 A g−1 (22 A cm2). The Cu incorporation in the hybrid material evoke loss of activity mostly due to Cu+ irreversible reduction/oxidation to Cu° and Cu2+, CuO segregation and influencing electron transfer process which results in the increasing in the redox potential. These results represent an important step towards light-enhanced electro-reactive systems and sensors in which heterojunction formation can facilitate electron-hole separation and enable more efficient energy transfer.

The current and estimated energy demand and their potential sources of supply indicate a daunting future for humanity on the planet unless sustainable solutions are developed. The scarcity, high cost and the potential environmental and health concerns related to widely used noble-metals make the situation even worse. Thus, active participation from scientific and industrial communities is essential to replace noble-metal (or any metal) based processes with more sustainable alternatives. In that context, recent developments in heteroatom-doped (especially nitrogen) nanocarbons and their wide-ranging applications show promises towards substituting the processes, which normally utilize expensive, scarce and hazardous materials. Herein, a brief overview of nitrogen-doped nanocarbons (NNCs) is provided highlighting their significance and sustainable prospects.

A single step synthetic procedure for carbon microspheres from agricultural waste residue (sugarcane bagasse) by low-temperature hydrothermal carbonization using oxalic acid as a hydrating/dehydrating agent is developed. The FTIR and XPS spectroscopy analysis indicates the presence of −OH, −COOH, and C═O functional groups on the surfaces of carbon spheres. These functional groups of the carbon spheres were utilized as a novel route to anchor 3-aminopropyl-triethoxysilane and 3-(2-aminoethylamino)propyl)-trimethoxysilane via condensation of triethoxy/trimethoxy silanes for the synthesis of organo base supported on carbon catalysts. The catalytic activity of the obtained supported organo-base catalyst was demonstrated for C–C bond forming (Henry) reaction. Among all prepared catalysts, 3-(2-aminoethylaminopropyl)-trimethoxysilane grafted in toluene showed high conversion (up to 100%) of aldehydes with excellent selectivity toward β-nitrostyrene. The catalyst was reused five times without losing significant ...