Perfect Catalyst Research Articles

Catalytic Enantioselective Primary C-H Borylation for Acyclic All-Carbon Quaternary Stereocenters.

Creating a perfect catalyst to operate enzyme-like chiral recognition has been a long-sought aim. A challenging example in this context is constructing acyclic all-carbon quaternary stereogenic centers by transition metal-catalyzed enantioselective C-H activation. We now report highly enantioselective iridium-catalyzed primary C-H borylation of α-all-carbon substituted 2,2-dimethyl amides enabled by a tailor-made chiral bidentate boryl ligand (CBL). The success of the current transformation is attributed to the CBL/iridium catalyst, which has a confined chiral pocket. This protocol provides a diverse array of acyclic all-carbon quaternary stereocenters with excellent enantiocontrol and distinct structural features. Computational study reveals that steric hindrance of CBL could regulate the type of dominant orbital interaction between the catalyst and substrate, which is crucial to conferring high chiral induction.

One-pot synthesis of CdS nanoparticles with surface-phase junctions to catalyze the photo-reduction of CO2 into CO and CH4 selectively

Without any external template & surfactant, CdS nanoparticles (NPs) with surface-phase junctions were synthesized directly from CdCl2 and the CS2-storage material (CS2SM) with a simple one-pot strategy, in which only stirring was needed. Under visible light irradiation, the as-synthesized CdS NPs could selectively catalyze the reduction of CO2 to produce CO and CH4 sustainably with a perfect catalyst stability even after 33 h. At 4 °C and the optical power density of 370 mW/cm2, the as-synthesized CdS NPs from 0.5 g CS2SM exhibited 195.41 μmol/gcat CH4 generation capacity and the 9.01 μmol·gcat−1·h−1 maximum average yield, in which the generation ratio of CH4/CO was at 8:2; and the as-synthesized CdS NPs from 2.0 g CS2SM exhibited 119.95 μmol/gcat CO generation capacity and the 3.75 μmol·gcat−1·h−1 maximum average yield, in which the generation ratio of CH4/CO was at 1:3. The research results indicated that CdS NPs with higher hexagonal content and smaller particle size is more active in CO2 photoreduction, which may be due to the low potential CdS NPs surface phase junction reducing the recombination rate of electron hole pairs and improving photocatalytic activity. The simple preparation of CdS NPs and their further photocatalytic CO2 reduction provide a green and sustainable foundation for the application of sulfide photocatalysts.

Environmental Remediation of Real Textile Dyeing Wastewater Under Visible Light and Inactivation of Pathogenic Bacteria Using ZnO/CuO Nano‐Needles

Textile industries have an immense existence in a country's economy. Large quantity of water is consumed by textile dyeing industries and produces volumes of wastewater. Treating these hazardous effluents to make them environmental friendly, using nanocatalysts is the best promising method. Metal oxide nanomaterials have emerged as an important tool for environmental remediation. Herein the hydrothermally synthesized ecofriendly and low‐cost zinc oxide/copper oxide nanocomposites (ZnO/CuO NCs) with different proportions of binary oxides are evaluated for the applications of degrading organic pollutants and antibacterial activity. The influence of doping is also studied in structural, optical, morphological, photocatalytic, and antibacterial activities. The presence of CuO in NCs affirms the formation of ZnO/CuO NCs. Photodegradation of Congo Red (CR) and real textile dyeing wastewater (TDW) under visible light irradiation by 0.5 M ZnO:0.5 M CuO NCs reveal them to act as a perfect catalyst by tuning doping concentration of Cu in ZnO, with 1.9 × 10−3 and 5.4 × 10−3 M min−1 rate constant. Hybrid nanocomposite materials exhibit high antibacterial activity against Staphylococcus aureus and Escherichia coli with 5 and 6 mm inhibition zone. The experimental characteristics of NCs are explained by a combination of electronic band structure due to size effect and tuning metal oxide proportions in comparison to that of pure metal oxide.

Ultrasonic-assisted synthesis of α-Fe2O3@TiO2 photocatalyst: Optimization of effective factors in the fabrication of photocatalyst and removal of non-biodegradable cefixime via response surface methodology-central composite design

Environmental pollution becomes a major worldwide issue that threatens the entire biosphere.On the other hand, visible-light photocatalysis technology is one of the most effective approaches to wastewater treatment due to its superb removal efficiency, facile process, and ecological friendliness.Herein, a highly efficient α-Fe2O3@TiO2 nanocomposite was synthesized using a rapid sonochemical technique and a conventional wet impregnation route for the elimination of cefixime. Towards achieve the optimal photocatalyst, the influences of operational parameters including calcination temperature (300–600 °C), and Fe2O3 loadings (1-5 wt%) were examined utilizing the Response Surface Methodology (RSM). Additionally, two important factors, irradiation time (3–8 min) and power (50–90 W) of ultrasonic waves, were investigated to optimize the efficiency, dimension, and structure of the photocatalyst. Then, the manufactured nanocomposites were characterized with the aid of techniques TEM, XRD, BET, FE-SEM, EDS-map, FTIR, and UV–Vis band gap analysis. The optimal photocatalyst (3.09 wt%, 439.34 °C, 70 W, and 8 min) was used to study the effect of four efficacious variables on cefixime removal by RSM. Maximum cefixime degradation (98.8%) occurred at optimum conditions (cefixime concentration = 20.5 mg/L, pH = 4.76, Irradiation time = 103 min and catalyst dose = 0.012 g/l). Based on the empirical data, statistical analysis proved the regression model's validity and adequacy. The COD elimination revealed that in comparison with other studies the α-Fe2O3@TiO2 photocatalyst could successfully mineralize cefixime (82.4%). Generally, the stability of α-Fe2O3@TiO2 in the photocatalytic degradation of cefixime was observed across five cycles with minimal iron leaching, making it a perfect catalyst for the removal of non-biodegradable pharmaceuticals.

Hydrogen Fuel-cell Technology in Electric Vehicles: Current Usage, Materials and Future Applications

A conventional combustion engine results in high greenhouse gas emissions, so the world is transforming to clean energy and electric vehicles. Developments and applications of hydrogen fuel cells in electric vehicles (EVs) lead the world toward a sustainable future. Hydrogen fuel applies to fuel cells and generates electricity through electrochemical reactions. It is exceptionally clean because the by-products are water and heat, so there has no visual pollution from vehicles. HFC technology is not commonly used for now but will take place in many EVs. Some countries planned to apply it to electric power systems, railways and spacecraft fields. Currently, HFC uses platinum as the main catalyst material because of its stability, high efficiency, and good performance that boosts the hydrogen and oxygen reactions. It is the most reliable source and a perfect catalyst that is widely applied. Other catalysts such as carbon-coated nickel, nitrogen-carbon mixtures (MNCs) and transition metal nitrides (TMNs) all show good performance and have similar efficiency with Pt. These materials could replace platinum in the future because Pt has limited sources and higher costs. Also, the study has found that scientists use ruthenium graphene as a catalyst in hydrogen fuel cells. However, its effectiveness needs long-term monitoring. Although HFC is a clean technology, it has disadvantages, for example, hard for hydrogen extraction and storage, lacking refueling systems etc. Current technology limits development, and barriers exist, such as overwhelming H2 storage and delivery and some safety issues. Even so, hydrogen energy and HFC application are the future for EVs and others.

Recent Progress in Green Conversion of Biomass Alcohol to Chemicals via Aerobic Oxidation

The aerobic oxidation of biomass transformations into valuable chemical products via a green catalytic process is one of the most important protocols because of its low reaction temperature and high productivity rate. Recently, the introduction of small-sized Cu and Au nanoparticles (e.g., 1–3 nm) upon the surface of oxides can provide more catalytic active sites and then enhance the catalytic activity of aerobic oxidations significantly. The introduction of these metal nanoparticles is a kind of perfect catalyst for enhancing the efficiency of the activation of oxygen molecules and the separation of photo-generated holes and electrons during the photo-oxidation reactions. In this account, we summarize recent progress of the aerobic oxidation of biomass alcohol toward the production of highly valuable chemicals over supported catalysts of metal nanoparticles (NPs), including methanol conversion into methyl formate via photo-oxidation over CuOx/TiO2 nanocomposites, biomass ethanol transformation with biomass furfural to produce hydrocarbons biofuels over Au/NiO catalysts, and glucose oxidation to gluconic acid using Au/activated carbon (Au/AC) as catalysts. Furthermore, at the atomic level, to understand the structure-property correlations, insights into molecular activations of oxygen and biomass, and the investigation of active catalytic sites on photo/catalysts will be detailed and discussed. Finally, future studies are needed to achieve more exciting progress in the fundamental revealing of the catalytic reaction mechanisms and conversion pathway and the future perspective in industrial applications.

Aristotle on Shame and Learning to be Good, by Marta Jimenez

How do we learn to be good? Aristotle’s answer will be familiar to any student of Greek philosophy: we become good—or virtuous—by doing virtuous actions. But how does the practice of virtuous actions give rise to virtuous dispositions, and, in particular, the disposition to choose virtuous actions as the virtuous person does – that is, for the sake of the noble (kalon)? These questions have long occupied readers of Aristotle’s ethics and offer the starting point for Marta Jimenez’s excellent monograph Aristotle on Shame and Learning to be Good. Jimenez is particularly concerned with the question ‘what are the conditions that make learners ready to receive the virtues and allow them to succeed in becoming good?’ (p. 18) and her answer—as indicated by her title—is that the presence of shame (aidōs, aischunē) is essential for ensuring that a learner acts in a way that is conducive to virtue. This book, then, can be seen as much as an attempt to rehabilitate shame as a positive emotion as it is to elucidate Aristotelian moral development. In fact, the primacy of Jimenez’s interest in shame is evident from her Introduction, which highlights the complex nature of shame and helpfully situates her interpretation of Aristotle’s account amongst contemporary treatments, both positive and negative. Against those who have expressed scepticism about a role for shame in moral theory and wariness of the dangers associated with ‘shame culture’, Jimenez argues that those features that have aroused suspicion—shame’s responsiveness to the views of others and to praise and blame—make it a perfect catalyst for moral development. According to Jimenez, shame is linked to ‘a concern with being seen as noble and expressing nobility (or avoiding shamefulness) in one’s actions because one aspires to genuine nobility and goodness’ (p. 11, emphasis added) and thus directs the attention of learners towards considerations of nobility when they act.

Manganese‐catalyzed amination reactions: An overview

As the nitrogen‐containing compounds have broad scope in biological, pharmaceutical, drug delivery, and material science, the C–N bond formation has vital role in synthetic chemistry. To provide a path for the inclusion of nitrogen in organic molecules, a facile establishment of C–N bonds is crucial. Manganese being inexpensive, nontoxic, and earth abundant is found to be a perfect catalyst to carry out amination, instead of using harsh reaction conditions or toxic metal catalysts. Herein, we discuss the manganese‐catalyzed amination reactions focusing on various manganese based catalysts for the C–N bond formation and covers the literature until 2020.

UV light assisted photocatalytic degradation of textile waste water by Mg0.8-xZnxFe2O4 synthesized by combustion method and in-vitro antimicrobial activities

In this paper, Magnesium Zinc Ferrite (MZF) nanoparticles (Mg0.8-xZnxFe2O4, where x = 0.2, 0.4 and 0.6) are successfully fabricated by combustion process. The prepared nanoparticles are characterized through XRD, FTIR, UV, SEM, EDS and TEM. It has been confirmed that the samples produced cubic spinel structure with crystal size in the range of 13–15 nm. From the ultraviolet spectrum, the optical band gap is calculated which ranges from 5.6 to 4.6 eV. TEM micrographs confirm the nanocrystalline nature of combustion derived ferrite nanoparticles with average particle diameter of 7–28 nm. Antibacterial studies confirmed that the nanoparticles are toxic to Pseudomonas aeruginosa consists of greatest zone of inhibition of 25 mm. The antibacterial and photocatalytic studies exhibited improved activity which is strongly influenced by the zinc doping. Photocatalytic degradation study reveal that the prepared nanoparticles function as perfect catalyst for degradation of Methylene Blue (MB) dye and Textile Dyeing Waste Water (TDWW) under UV light, thus revealing their potential usage on organic pollutants.

Influence mechanism of supports for the adsorption and dissociation of H2O and toluene in toluene steam reforming

In this paper, we systematically study the adsorption behavior of H2O and toluene on the naked and Ni-decorated surface of supports including Al2O3, MgO, CeO2, ZrO2 and MgAl2O4, and explore the synergistic effect between Ni and the support on the dissociation of H2O and toluene using density functional theory. The results show that H2O is most easily adsorbed on Al2O3(110), followed by MgAl2O4 (111), while the toluene is most easily adsorbed on MgAl2O4(111). Besides, MgAl2O4(111) holds perfect bonding capacity with Ni. The adsorption of H2O on Ni-MgAl2O4(111) is dissociative adsorption, and the dissociation barrier of toluene on Ni-MgAl2O4(111) is lowest, which is only 1.0 kcal/mol. The above characteristics demonstrate that MgAl2O4 is expected to be the perfect toluene steam reforming support comparing to other supports, and Ni-MgAl2O4 can show perfect catalyst activity and stability during toluene steam reforming reaction.

Education and the Economy of Attention in Times of (Post-) Pandemic

With the Coronavirus crisis, online teaching seems to have become a norm in Higher Education. The essay argues that, although this new pedagogical practice is totally acceptable in times of social distancing, it can lead to something more radical, especially with the strong will of HE institutions to continue this mode of teaching beyond the period of crisis. The normalisation of dematerialised teaching comes as a challenge to academics: it is imbedded in a new form of economy, where attention is a key source of value and labour. The omnipresence of virtual interfaces questions the very fabric of their practice as teachers, especially in humanities, where it can lead to an intensification of the pauperization of teaching staffs, due to forced redundancy. To understand how the normalisation of online teaching after the crisis can be potentially noxious, the essay proceeds by looking at the change of agency of digital tools in teaching contexts, through the concept of pharmakon, developed by Bernard Stiegler, that offers the chance for a critique of this new pedagogical strategy which can be positive during the crisis, but potentially destructive after. This concept leads to a new criteria of judgment of the digital (mode of teaching), which has to be understood as a third way between the optimism of managerial perspectives, always keen to consider information technologies as the perfect catalyst for neo-liberal reforms in education; and the traditional technophobia, proper to a philosophical tradition that, from the Frankfurt School to Giorgio Agamben, apprehends the mediation of technology essentially as a critical regression and a modern form of rationalisation that engenders an immense social and psychic alienation.

The Transformation by Catalysis of Prebiotic Chemical Systems to Useful Biochemicals: A Perspective Based on IR Spectroscopy of the Primary Chemicals II. Catalysis and the Building of RNA

Having found that carbonyl sulfide (COS), works well as a catalyst in the transformation of amino acids to polypeptides, we have now tested COS as a catalyst also for the formation of substances that might be thought of as partners in the building of RNA. The model used was selective energy transfer (SET). This model implies that a certain number of vibrational quanta are donated from the catalyst system and a corresponding number of quanta of the reactant accept the energy thus transferred. In this way, we found that carbonyl sulfide, COS, was a perfect catalyst for combining, first, five molecules of formaldehyde to form one molecule of ribose, and next, five molecules of hydrogen cyanide, HCN, to form one molecule of adenine, one of the nucleobases of RNA. However, beyond this, we found that COS was a perfect catalyst for precisely all reactions, needed to build the RNA, ribonucleic acid.

Crystalline MoP-amorphous MoS2 hybrid for superior hydrogen evolution reaction

Molybdenum disulfide (MoS2) is regarded as a perfect catalyst for electrochemical hydrogen evolution reaction (HER). However, the active sites are usually concealed due to the unique two dimensional structure of MoS2. Herein, we propose a facile surface engineering modus to improve the HER activity of MoS2. This strategy is demonstrated by in-situ growth of amorphous MoS2 layer on the molybdenum phosphide (MoP) nanoparticles anchored on the carbon nanotubes (MoS2/MoP/CNT). The HER activity is significantly promoted both through the defect engineering of amorphous MoS2 and the synergistic effect between the MoS2 and MoP phases. The MoS2/MoP/CNT sample presents significantly higher HER performance than the pure phase of MoP/CNT and MoS2/CNT samples, requiring overpotentials of 73 and 141 ​mV to drive a current density of 10 and 100 ​mA ​cm-2.

In-situ synthesis of hierarchical lamellar ZSM-5 zeolite with enhanced MTP catalytic performance by a facile seed-assisted method

A seed-assisted route has been applied to prepare the hierarchical lamellar ZSM-5 zeolite with good porosity and catalytic performance in methanol to propylene (MTP) reaction. In this method, ZSM-5 crystal seeds instead of organic quaternary ammonium were used to direct the formation of ZSM-5 nuclei and conventional surfactant cetyltrimethylammonium bromide (CTAB) employed as the mesoporogen. The process for the formation of hierarchical lamellar ZSM-5, including the effect of the ratio of CTAB/SiO2, initial gel aging temperature, synthesis temperature and synthesis time were discussed in detail. The results suggested that mesoporous structure was first obtained and then transformed into MFI structure in-situ during the hydrothermal synthesis process. The obtained hierarchical lamellar ZSM-5 zeolite displays an organized flack-like nanosheet stacks morphology with regular intercrystal mesopores of 3–7 nm, possessing large surface area and mesopore volume. Moreover, the synthesized hierarchical ZSM-5 zeolite has perfect catalyst lifetime in methanol to propylene (MTP) reaction than conventional microporous ZSM-5 zeolite, which could be ascribed to the hierarchical mesoporous structure accommodating more bulky molecules and accessible acid sites in the catalytic reaction.

A Challenge to the G ∼ 0 Interpretation of Hydrogen Evolution

Platinum is a nearly perfect catalyst for the hydrogen evolution reaction, and its high activity has conventionally been explained by its close-to-thermoneutral hydrogen binding energy (G ∼ 0). How...

Kinetic study of hydrogen sulfide decomposition on Pt(111) surface

AbstractIn this work, kinetic of H2S conversion to H2 molecule on the surface of Pt(111) is studied using kinetic Monte Carlo simulation. The results of simulation were fitted to the experimental temperature‐programed desorption spectra. The good agreement between the empirical and the simulated data confirms the proposed mechanism and kinetic data (activated energies and pre‐exponential factors). The influence of variables such as temperature and concentrations of H2S and H2 on the overall results of hydrogen production is studied. The condition is proposed in which the best yield of reaction at minimum temperature is obtained. Results show that platinum is a perfect catalyst for converting H2S to H2 and it has a perfect performance (98%) after 5 μs at low temperature of 227°C.

Density-functional theory study on hydrogenation of dimethyl oxalate to methyl glycolate over copper catalyst: Effect of copper valence state

The development of high-performance copper (Cu)-based catalysts is critical to achieve the industrial hydrogenation of dimethyl oxalate (DMO) to methyl glycolate (MG). To understand the effect of Cu valence state on MG formation, a theoretical study was performed over Cu+-perfect, Cu+-defective, Cu0, and Cu0/Cu+ catalysts by density-functional theory calculations. Calculations showed that the rate-limiting step (RLS) on the Cu+-perfect catalyst was H2 dissociation, whereas CH3OOCCHOH hydrogenation becomes the RLS for the Cu+-defective catalyst. For Cu0 and Cu0/Cu+, DMO dissociation was the RLS. Compared with other three catalysts, Cu0/Cu+ bicomponent catalyst needed to overcome the lowest barrier (168.6 kJ/mol), which is suggested to be an optimal catalyst for selective DMO hydrogenation. The remarkable catalyst efficiency was ascribed to the synergistic effect between the Cu0 and Cu+ sites. The calculation results indicated that Cu0 was beneficial to the dissociation of H2 and was primarily responsible for the hydrogenation (CH3OOCCO-MG), whereas Cu+ was beneficial to DMO dissociation. Besides, Cu+ stabilized intermediates. In summary, we have found that the adsorption energy of CH3OOCCO+H can be considered as the catalyst performance descriptor through the calculation results. Because Cu0/Cu+ agreed with the index of moderate adsorption energy, Cu0/Cu+ presented the best catalytic performance.

From agriculture residue to catalyst support; A green and sustainable cellulose-based dip catalyst for C[sbnd]C coupling and direct arylation

The core characteristics of a perfect catalyst include good activity, simple design, excellent stability, easy recovery from reaction mixture, recyclability, and have the provision for easy scale up. The ease in synthesis, recyclability and scale up makes the dip catalyst a major contender in this regard which possess most of the aforementioned characteristics. In this work, we report a dip catalyst made of cellulose, isolated from agriculture residue (sugarcane bagasse), in which biogenically synthesized palladium nanoparticles were dispersed. The prepared dip catalyst was characterized by FESEM, EDS, XRD, ATR-IR, TGA, TEM, XPS and ICP-OES analysis. Also, the activity of the dip catalyst was studied in the Suzuki-Miyaura cross-coupling reaction and was found to give excellent conversion with 15 recycles. Further, the activity of dip catalyst in C5-arylation of 2-substituted thiophenes was evaluated for which promising yields were obtained.

Seeking active RubisCOs from the currently uncultured microbial majority colonizing deep-sea hydrothermal vent environments.

Almost all the inorganic carbon on Earth is converted into biomass via the Calvin-Benson-Bassham (CBB) cycle. Here, the central carboxylation reaction is catalyzed by ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO), which can be found in numerous primary producers including plants, algae, cyanobacteria, and many autotrophic bacteria. Although RubisCO possesses a crucial role in global biomass production, it is not a perfect catalyst. Therefore, research interest persists on accessing the full potential of yet unexplored RubisCOs. We recently developed an activity-based screen suited to seek active recombinant RubisCOs from the environment-independent of the native host's culturability. Here, we applied this screen to twenty pre-selected genomic fosmid clones from six cultured proteobacteria to demonstrate that a broad range of phylogenetically distinct RubisCOs can be targeted. We then screened 12,500 metagenomic fosmid clones from six distinct hydrothermal vents and identified forty active RubisCOs. Additional sequence-based screening uncovered eight further RubisCOs, which could then also be detected by a modified version of the screen. Seven were active form III RubisCOs from yet uncultured Archaea. This indicates the potential of the activity-based screen to detect RubisCO enzymes even from organisms that would not be expected to be targeted.

Discover, Instrumentalize, Monopolize: Fidesz’s Three-Step Blueprint for a Populist Take-over of Referendums

This article assesses the referendums in Hungary in 2004, 2008, and 2016 diachronically. The review is framed by two competing liberal parliamentary approaches to direct democracy: A useful democratic corrective to the distortions of particracy, or a risky option leading to tyranny of the majority? Rather than choosing sides, this article shows how the conundrum conceals another, more interesting question: Which are the constraints under which the liberal parliamentary viewpoint shifts from the one to the other? Theorizing on post-democracy and populism provides a provisional answer: A consensualized, “post-political” parliament is key, as this, in combination with widening social-economic disparities, incentivizes illiberal populist parties to harness referendums, which prompts liberal parliamentarianists to change their minds. The referendums in 2004, 2008, and 2016 in Hungary substantiate this suspicion. Taken together, they offer a step-by-step blueprint for how, in a thoroughly postpolitical situation, a referendum evolves into a perfect catalyst for populists on their road to power, enabling them with (a) agenda-setting; (b) an explosive emphasis on popular legitimacy; (c) arousing voluntarism, while luring opponents into campaigning for boycott and political apathy; (d) combining social equalitarianism with identarian protectionism, and most importantly; (e) bypassing parliament itself. This article is part of the special cluster titled Political Parties and Direct Democracy in Eastern Europe, guest-edited by Sergiu Gherghina.