Catalytic Nature Research Articles

Nitrogen Fixation at the Edges of Boron Nitride Nanomaterials: Synergy of Doping.

Synthesis of ammonia at ambient conditions is very demanding yet challenging to achieve due to the production of ammonia fuel, which is considered to be a future fuel for sustainable energy. In this context, computational studies on the catalytic activity of the edge sites of boron nitride nanomaterials for possible nitrogen reduction into ammonia have been investigated. Geometrical and electronic properties of zigzag and armchair B-open edges of BN sheet (BOE) models have been unraveled to substantiate their catalytic nature. Results reveal that BOE sites exhibit very high potential determining steps (PDS) of 2.0 eV. Doping of carbon (C) at the nitrogen center, which is vicinal to the BOE site reduces the PDS of the N2 reduction reaction (NRR) (to 1.18–1.33 eV) due to the regulation of charge distribution around the active BOE site. Further, the NRR at the C doped at various edge sites of a boron nitride sheet (BNS) has also been studied in detail. Among the 12 new C-doped defective BNS models, 9 model catalysts are useful for nitrogen activation through either chemisorption or physisorption. Among these, ZC N , AC N , and ZC BV models are efficient in catalyzing NRR with lower PDS of 0.86, 0.88, and 0.86 eV, respectively. The effect of carbon doping in tuning the potential requirements of NRR has been analyzed by comparing the relative stability of intermediates on the catalyst with and without carbon doping. Results reveal that C-doping destabilizes the intermediates compared to non-doped systems, thereby reducing the possibility of catalyst poisoning. However, their interactions with catalysts are good enough so that the NRR activity of the catalyst does not decrease due to C-doping.

One-pot microwave synthesis of SnSe and Lanthanum doped SnSe nanostructure with direct Z scheme pattern for excellent photodegradation of organic pollutants

A novel nanostructure photocatalytic material was fabricated using Lanthanum doped SnSe by one-pot microwave method is reported to newest. Photocatalytic performance efficiency of pristine SnSe and Lanthanum doped SnSe nanostructures were investigated to degrade organic pollutants from wastewater. The crystal structure, morphology, and optical properties of the nanostructure were investigated using powder X-ray diffraction, field emission scanning electron microscope, UV–Vis, and PL spectral studies. Nano rods/spheres for pure SnSe were altered significantly leading to higher amounts of nanorods due to La doped and increase in concertation leads higher formation of nanorods. Increased in structure and morphology played a vital role in photocatalytic activity. Nanostructure exhibits enhanced physicochemical properties and showed an excellent synergetic effect demonstrating the effect of La (1, 3, and 5%) concentrations in SnSe nanostructure. The optical energy gap has a reducing trend due to the increment of doping concentration. The individual elements oxidation states were justified from X-ray photoelectron spectroscopical studies. Thermal stability and phase changes of the nanostructure before and after doping of La were evaluated through TGA/DTA analysis. From the photocatalytic measurement rare-earth (La) doped samples expressed higher catalytic nature than the pure SnSe. It was observed that the higher atomic element La had a significant role to produce a large number of electron-hole pair recombination and defective structure in the host lattice.

PROTACs: past, present and future.

Proteolysis-targeting chimeras (PROTACs) are heterobifunctional molecules consisting of one ligand that binds to a protein of interest (POI) and another that can recruit an E3 ubiquitin ligase. The chemically-induced proximity between the POI and E3 ligase results in ubiquitination and subsequent degradation of the POI by the ubiquitin-proteasome system (UPS). The event-driven mechanism of action (MOA) of PROTACs offers several advantages compared to traditional occupancy-driven small molecule inhibitors, such as a catalytic nature, reduced dosing and dosing frequency, a more potent and longer-lasting effect, an added layer of selectivity to reduce potential toxicity, efficacy in the face of drug-resistance mechanisms, targeting nonenzymatic functions, and expanded target space. Here, we highlight important milestones and briefly discuss lessons learned about targeted protein degradation (TPD) in recent years and conjecture on the efforts still needed to expand the toolbox for PROTAC discovery to ultimately provide promising therapeutics.

Effects of alloying for steam or dry reforming of methane: a review of recent studies

A survey on the catalytic nature of Ni-based alloy catalysts in recent years provides a direction for future catalyst development.

Generation of singlet oxygen catalyzed by the room-temperature-stable anthraquinone anion radical.

The chemical nature and the catalytic selectivity of the complex of anthraquinone and potassium tert-butoxide, AQ-KOtBu, in generating singlet oxygen (1O2) have been studied using a high-level ab initio method and density functional theory (DFT). The results suggest that the stable catalytic center of the AQ anion radical (semiquinone, [AQ˙]-) can be produced at room temperature, which is due to the strong delocalization characteristics of electrons in potassium atoms. Two experimentally observed complexes, the ground state AQ-KOtBu, i.e., C(1), and the photoexcited AQ-KOtBu, i.e., C(2), can be distinguished via the two different electronic states (π-type and σ-type) of the tert-butoxide group. More interestingly, the catalytic selectivity of AQ-KOtBu to generate 1O2 was investigated using multistate density functional theory (MSDFT), and the results suggest that only open-shell 1O2 rather than the closed-shell component can be generated. This work explores the electronic structure and the catalytic nature of AQ-KOtBu, which is of great importance for the application of AQ and its derivatives.

Catalytic Scenarios Over Metal-Carbon Interaction Interface.

Numerous efforts have been devoted to investigating the catalytic events and disclosing the catalytic nature of the metal-carbon interaction interface. Nevertheless, the local deconstruction of catalytically active metal-carbon interface was still missing. Herein, the selected four types of landmark catalytic paradigms were highlighted, which was expected to clarify their essence and thus simplify the catalytic scenarios of the metal-carbon interface—carbon-supported metal nanoparticles, carbon-confined single-atom sites, chainmail catalysis, and the Mott-Schottky effect. The potential challenges and new opportunities were also proposed in the field. This perspective is believed to give an in-depth understanding of the catalytic nature of the metal-carbon interaction interface and in turn provide rational guidance to the delicate design of novel high-performance carbon-supported metal catalysts.

High Fluorescence Porous Organic Cage for Sensing Divalent Palladium Ion and Encapsulating Fine Palladium Nanoparticles

Comprehensive SummaryPorous organic cages (POCs) as an innovative type of porous molecular materials enable multifunctional applications. Herein, a fluorescence POC (denoted as 1) has been constructed by means of 5,5'‐((2,5‐dimethoxy‐1,4‐phenylene)bis(ethyne‐2,1‐diyl))diisophthalaldehyde condensing with cyclohexanediamine enantiomer with the aid of trifluoroacetic acid. 1 exhibits the permanent void and prominent fluorescence with relative quantum yield of 73% confirmed by gas sorption and emission experiments, respectively. Moreover, this organic cage is capable of sensing diavalent Pd2+ according to the fluorescence response to the addition of various metal ions. The dispersion of 1 in methanol containing palladium acetate was stirred at 25 oC and then 80 oC to reduce Pd2+ ions into nanoparticles (NPs), leading to the composite (Pd@1) composed of fine Pd NPs with the size of ca. 1.8 nm. The catalytic nature of Pd@1 over NaBH4 promoted the degeneration of nitrobenzene and congo red. This work introduces one new case of POCs with versatile properties and functions, including ion fluorescence recognition, fine Pd NPs stabilizer, and gas adsorption, enriching the family of POC‐based materials.

Oxidative Dehydrogenation of Propane with Carbon Dioxide Catalyzed by ZnxZr1–xO2–x Solid Solutions

Although the oxidative dehydrogenation of propane with CO2 (CO2-ODP) is a sustainable route for producing propylene with the tandem conversion of CO2 to the value-added CO, its industrialization is still challenged by the lack of an efficient catalyst, which originates from the insufficient understanding of the catalytic nature and reaction mechanism. In this work, ZnO-ZrO2 composites were probed as catalysts for CO2-ODP. A pure ZnxZr1–xO2–x solid solution was formed over ZnO-ZrO2 composites with 5–20 mol % ZnO, and the content of oxygen defects was almost directly proportional to the fraction of the solid solution. The amount and the mobility of lattice oxygen over ZnxZr1–xO2–x solid solutions were revealed as key factors in determining the catalytic performance. The CO2-ODP reaction over the best 20 mol %ZnO-ZrO2 catalyst occurred almost stoichiometrically via the redox mechanism, which can be an important guideline for further developing a high-performance catalyst for CO2-ODP.

High‐entropy alloys and compounds for electrocatalytic energy conversion applications

AbstractHigh‐entropy materials, composed of five or more elements in near‐equiatomic percentage, have been attracting tremendous interests due to their advantageous properties in a variety of applications. Recently, electrocatalysis on high‐entropy alloys (HEAs) and high‐entropy compounds (HECs) has emerged as a new and promising material owing to the tailored composition and the disordered configuration of HEAs and HECs. Though extensive efforts have been devoted to investigating the catalytic nature of HEAs and HECs, the details related to the active sites and intrinsic activity of such catalysts still remain uncertain due to the complexity of the multicomponent systems. In this review, the recent progress of HEAs and HECs is systematically reviewed in terms of their synthetic strategies and electrocatalytic applications. Importantly, the computationally assisted methods (e.g., density functional theory [DFT]) are also presented to discover and design the optimum HEA‐ and HEC‐based catalysts. Subsequently, the applications of HEAs and HECs in electrocatalytic energy conversion reactions will be discussed, including hydrogen evolution reaction, oxygen evolution reaction, oxygen reduction reaction, carbon dioxide reduction reaction, nitrogen reduction reaction, methanol oxidation reaction, and ethanol oxidation reaction (EOR). Moreover, the prospects and future opportunities for this research field are cautiously discussed. A series of upcoming challenges and questions are thoroughly proposed from the experimental and theoretical aspects as well as other future applications in electrocatalysis.

Graphene and Carbon Nanotubes Fibrous Composite Decorated with PdMg Alloy Nanoparticles with Enhanced Absorption-Desorption Kinetics for Hydrogen Storage Application.

We describe a graphene and fibrous multiwall carbon nanotubes (f-MWCNT) composite film prepared by plasma-enhanced chemical vapor deposition for use as a suitable and possible candidate of hydrogen storage materials. A high storage capacity of 5.53 wt% has been obtained with improved kinetics. The addition of binary PdMg alloy nanoparticles to the surface of graphene-fibrous nanotubes composite films raised the storage capacity by 53% compared to the film without PdMg decorated nanoparticles. Additionally, the graphene/f-MWCNT composite film decorated with PdMg nanoparticles exhibited an enhanced hydrogen absorption–desorption kinetics. The fibrous structure of the MWCNTs, alongside graphene sheets within the film, creates an enormous active region site for hydrogen reaction. The addition of PdMg nanoparticles enhanced the reaction kinetics due to the catalytic nature of Pd, and increased the hydrogen content due to the high absorption capacity of Mg nanoparticles. The combination of Pd and Mg in a binary alloy nanoparticle enhanced the hydrogen capacity and absorption–desorption kinetics.

Catalytic properties and nature of active centers of Cr/MCM-41 in catalytic abatement of sulfur-containing VOC of methanethiol

A series of MCM-41 supported Cr catalysts, with different amounts of Cr (1, 10, 18, 22 wt%), were synthesized and applied for catalytic abatement of sulfur-containing VOC of methanethiol (CH3SH). The results showed that 18%Cr/MCM-41 exhibited enhanced activity than that of the reported catalysts. Characterization results of XRD, UV–Vis, FT-IR and XPS suggested that catalyst with low amount of Cr (1 wt%) contained mainly Cr(VI) species. With the increase of Cr amount, partial Cr(VI) species were aggregated and reduced into inactive Cr(III) species, and the optimum amount of Cr was 18 wt%. The presented Cr(VI) species was found to play an significant role and regarded as the active sites in the decomposition of CH3SH. Moreover, a comparative study between the fresh and the spent samples provided a direct proof to illustrate the active property of Cr(VI) state in the process of CH3SH abatement. Besides, design-oriented experiments through using mechanical mixtures of Cr2O3 and CrO 3 with MCM-41 solid were performed, giving some insights into the potential role of active Cr(VI) sites. Notably, additional experiments regarding the mixing of carbon black and 18%Cr/MCM-41 suggested the elimination of deposited carbon for Cr/MCM-41.

Palladium complex of sulphated schiff base with ortho-vanillin as catalyst for O-arylation of phenol

Organochalcogen compounds due to their hassle-free synthesis and air and moisture insensitive nature have attracted substantial attention in scientific world. They have profound applications in the development of catalytic systems that have emerged as efficient catalysts in various chemical transformations. Organochalcogen ligands have contributed to the backbone of several catalytic systems used for O-arylation reaction which is an effective tool for the synthesis of diaryl ether substituents. Synthesis of several bioactive compounds rely on this method. A thioether ligand L1 has been prepared by reaction of 3-(chloropropyl)amine hydrochloride with the insitu generated PhSNa. The L1 has been condensed with o-vanillin to synthesize ligand L2 having imine functionality. The structure of ligand L2 has been authenticated using proton and carbon-13 NMR techniques. The synthesis of an efficient N, S coordinated bidentate novel palladium complex 1 ([Pd(L2)Cl2]), by the reaction of ligand L2 with [PdCl2(CH3CN)2] in chloroform-hexane system has been carried out. The structure of 1 has also been corroborated by 1H ,13C{1H} NMR and mass spectroscopic techniques. Its catalytic potential has been tested for etherication of various aryl bromides with phenol. Cheaply available aryl chlorides have also been coupled to determine the efficiency of Pd(II) complex 1. The complex 1 gave good yields while exhibiting excellent tolerance towards electronically diverse aryl halides with 0.5 mol% catalyst loading. The nature of catalysis has been found to be purely homogeneous on conducting mercury and triphenylphosphine poisoning tests.

Regulating Vacuum Tribological Behavior of a-C:H Film by Interfacial Activity.

A hydrogenated amorphous carbon (a-C:H) film shows an ultralow friction coefficient (COF, lower than 0.01); however, its wear life is short in vacuum, and the mechanisms are still not well-understood. This study demonstrates the vacuum tribological behaviors of the a-C:H film can be regulated by interfacial activity. The strong interfacial activity induced continuous transfer of carbon from the film to counterface, causing the formation of a porous transfer film and severe wear of the a-C:H film. Interestingly, weak interfacial activity is beneficial to form spherical-like carbon at the sliding interface, which shields the interaction of dangling bonds and contributes to lower COF and wear of film. Notably, the catalytic nature of Au induced perfect graphene nanoscrolls around Au nanoparticles at the sliding interface, achieving ultralong vacuum wear life. This Letter unifies the understanding of vacuum tribological properties of a-C:H film and provides new insight for prolonging the life of carbon films in vacuum.

Nanozyme-Participated Biosensing of Pesticides and Cholinesterases: A Critical Review.

To improve the output and quality of agricultural products, pesticides are globally utilized as an efficient tool to protect crops from insects. However, given that most pesticides used are difficult to decompose, they inevitably remain in agricultural products and are further enriched into food chains and ecosystems, posing great threats to human health and the environment. Thus, developing efficient methods and tools to monitor pesticide residues and related biomarkers (acetylcholinesterase and butylcholinesterase) became quite significant. With the advantages of excellent stability, tailorable catalytic performance, low cost, and easy mass production, nanomaterials with enzyme-like properties (nanozymes) are extensively utilized in fields ranging from biomedicine to environmental remediation. Especially, with the catalytic nature to offer amplified signals for highly sensitive detection, nanozymes were finding potential applications in the sensing of various analytes, including pesticides and their biomarkers. To highlight the progress in this field, here the sensing principles of pesticides and cholinesterases based on nanozyme catalysis are definitively summarized, and emerging detection methods and technologies with the participation of nanozymes are critically discussed. Importantly, typical examples are introduced to reveal the promising use of nanozymes. Also, some challenges in the field and future trends are proposed, with the hope of inspiring more efforts to advance nanozyme-involved sensors for pesticides and cholinesterases.

Key Considerations When Assessing Novel Fenton Catalysts: Iron Oxychloride (FeOCl) as a Case Study.

Iron oxychloride (FeOCl) has been reported to be a highly efficient heterogeneous Fenton catalyst over a wide pH range. In order to determine the true catalytic performance of FeOCl, we simultaneously quantified the adsorptive and oxidative removal of formate, oxalate, and rhodamine-B (RhB) and the formation of RhB oxidation products at both pH 4.0 and 7.0. FeOCl was found to be a poor Fenton catalyst at either pH, as gauged by the oxidation of formate, oxalate, and rhodamine B and the decomposition of H2O2, in comparison with ferrihydrite (Fhy), one of the most common Fe-containing Fenton catalysts. The adsorption of target contaminants to FeOCl and homogeneous Fenton processes, induced by dissolved iron, resulted in overevaluation of the catalytic performance of FeOCl, especially for (i) the use of strongly adsorbing target compounds, without consideration of the role of adsorption in their removal and (ii) exceedingly high concentrations of H2O2 to remove trace quantities of target contaminants. Overall, this study highlights that the systematic quantification of H2O2 decomposition, target compound adsorption, and oxidation as well as the concentrations of oxidized products formed are prerequisites for unequivocal elucidation of the catalytic nature and reaction mechanism of solid Fenton catalysts.

Highly Efficient Active Colloids Driven by Galvanic Exchange Reactions.

Micromotors are propelled by a variety of chemical reactions, with most of them being of catalytic nature. There are, however, systems based on redox reactions, which show clear benefits for efficiency. Here, we broaden the spectrum of suitable reactions to galvanic exchange processes, or an electrochemical replacement of a solid metal layer with dissolved ionic species of a more noble metal. We study the details of motility and the influence of different reaction parameters to conclude that these galvanophoretic processes circumvent several steps that lose efficiency in catalytic micromotors. Furthermore, we investigate the chemical process, the charge, and flow conditions that lead to this highly efficient new type of active motility. Toward a better understanding of the underlying processes, we propose an electrokinetic model that we numerically solve via finite elements.

Trimetallic@Cyclodextrin Nanocomposite: Photocatalyst for Degradation of Amoxicillin and Catalyst for Esterification Reactions

The industry is looking for new materials which can respond to specific applications that exclusively advance materials can provide. In this context, nanoparticles and nanocomposites opened an interesting method for designing specific properties which can be modulated according to the requirements. The preparation of biomolecules supported trimetallic nanoparticles and some other derives is a good example of the complex systems that can be designed for getting exclusive properties. This study is based on the preparation of new cyclodextrin supported Fe/La/Zn trimetallic nanocomposite by the microemulsion technique. Photocatalytic degradation of amoxicillin was performed using cyclodextrin-Fe/La/Zn. 78% of amoxicillin photodegradation along 4 hours of photoirradiation was achieved. Finally, the catalytic nature of new material was explored for oxidation and esterification reactions. The present study revealed that this advanced multifunctional nanomaterial can be successfully employed for environmental remediation and catalytic activities.

The trapping of methane on Ir(111): A first-principles quantum study.

We implement a fully quantum mechanical study of methane trapping on Ir(111), where the phonons, the molecule-surface interaction, and the molecule-phonon coupling are all computed from first-principles. We find that both the surface corrugation and the phonon coupling vary strongly with molecular orientation and that there is a "chemical" aspect to this due to the catalytic nature of the metal. For example, molecules with reactive orientations can approach close to surface sites with low barriers to dissociation. Moreover, lattice motion can lower the barrier to dissociation, leading to unusual behavior for the phonon coupling. We find good agreement with experiment and two recent classical studies if we average our potential energy surface over several orientations of the molecule. We also find reasonable agreement with a recent study of methane diffraction, although we show that diffraction does not play a major role in trapping on the smooth Ir(111) surface and that trapping obeys normal energy scaling, consistent with experiment. We show that the trapping probability can be sensitive to the temperature at both high and low incidence energies. Relaxation and desorption of trapped particles are examined.

Autonomous magnetic microbots for environmental remediation developed by organic waste derived carbon dots

Biodegradable precursors for micro/nanobots development are key requirements for several sustainable applications. In this regard, we propose an innovative solution for water purification at minimum cost and efforts where organic waste is used for the treatment of organic pollutants. Herein, catalytic magnetic microbots were developed by functionalizing iron oxide nanoparticles with carbon dots (C-Dots), which were synthesized by using household waste such as potato peels as precursors. The speed of these autonomously propelling bots indeed is found very promising for large distance swimming even in viscous medium by using hydrogen peroxide as fuel. These microbots catalytically propel and degrade toxic polar as well as sparingly water-soluble industrial dyes without any external agitation. The degradation of dyes was confirmed by mass-spectra analysis. Furthermore, these microbots can efficiently degrade a mixture of dyes and reused without compromising its performance significantly. Additionally, rate constant (K) and activation energy (Ea) were also determined to establish the catalytic nature of the bots. The present microbots acted as nanozyme owing to its synergistic catalytic activity of Fe3O4 and C-Dots for degradation of mixture of toxic dyes, essential for large scale water treatment.

Gene Silencing Therapeutics in Cardiology: A Review Article

Therapeutics that inhibit enzymes, receptors, ion channels, and cotransporters have long been the mainstay of cardiovascular medicine. Now, oligonucleotide therapeutics offer a modern variation on this paradigm of protein inhibition. Rather than target a protein, however, small interfering ribonucleic acids and antisense oligonucleotides target the messenger RNA (mRNA) from which a protein is translated. Endogenous, cellular mechanisms enable the oligonucleotides to bind a selected sequence on a target mRNA, leading to its degradation. The catalytic nature of the process [...]