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This paper details the preparation of an aluminum-based organic metal complex doped with fluorine and nitrogen (2-Ml/Al–F–N). The synthesis method combines hydrothermal synthesis and calcination for modification. The catalyst was thoroughly characterized for its composition, structure, and morphology using various techniques, including XRD, FT-IR, XPS, SEM, TEM, and others. The electrochemical performance of the material was assessed using an electrochemical workstation, and gas chromatography was employed to analyze the results. DFT calculations were used to compute the material's properties and energy barrier diagram. The findings demonstrate that the catalyst exhibits a carbon nanoline morphology and showcases high catalytic activity in the CO2RR to CO. Notably, the catalyst exhibits excellent performance with a maximum current density of 14.08 mA cm−2 and a peak faradaic efficiency of 90.1% at −1.1 V vs. RHE. The active sites are predominantly located within the nanoline structure. The DFT calculations reveal that the introduction of ammonium fluoride during the synthesis process leads to the formation of a highly efficient fluorinated aluminum metal catalytic center derived from nonahydrate aluminum nitrate. This specific structure demonstrates excellent hydrogen suppression properties and effectively lowers desorption energy barriers, which enhances the CO2RR activity and promotes the electrocatalytic reduction of CO2 to CO. [ABSTRACT FROM AUTHOR]

In this paper, a novel Pt/CoP/C photo-electro synergistic catalyst was successfully synthesized by a hydrothermal method combined with phosphorus doping treatment. The addition of Vulcan XC-72R is in favor of effectively preventing agglomeration of active catalytic sites, resulting in more uniform and smaller Pt and CoP nanoparticles. The as-obtained Pt/CoP/C shows excellent photo-electro catalytic performance for the HER with simulated solar light irradiation. The optimal hydrogen production is 5384.18 mmol h−1 g−1, which is obviously higher than that of the commercial catalyst (20 wt% Pt/C: 4608.52 mmol h−1 g−1). The research results show that introducing cobalt phosphide into the Pt catalyst can improve the electrocatalytic activity and stability for the HER; in particular, the existence of Co3O4 in Pt/CoP/C leads to an efficient photo-electro catalysis under irradiation, which significantly improves the catalytic activity of Pt. The results above provide a novel strategy for the rational design of cost-effective Pt-based composites towards a fast HER. [ABSTRACT FROM AUTHOR]

Developing low-cost and efficient catalysts for the oxidation of formaldehyde (HCHO) is crucial for preservation of the environment. The main challenge of this study is how to develop an efficient, stable, and inexpensive catalyst that can oxidize HCHO at low temperatures. Herein, the reduced Mn-doped cobalt tetroxide R-MnxCo3−xO4 catalyst was prepared by simple co-precipitation and annealing treatment followed by reduction of NaBH4. The prepared R-MnxCo3−xO4 showed remarkable enhanced activity for HCHO oxidation at low temperature. The R-MnCo2O4 catalyst can oxidize and decompose 79% of HCHO at a low temperature of 50 °C and exhibits excellent catalytic stability. The improved catalytic activity can be attributed to the increase in oxygen vacancy concentration and the improvement in redox performance. The TGA test shows that the content of oxygen vacancies in the R-MnCo2O4 catalyst can reach 5.77% (atomic ratio). The H2-TPR, O2-TPD and O2-TPO tests indicated that the surface oxygen vacancies can promote oxygen mobility and facilitate the formation of reactive oxygen species during the formaldehyde catalytic oxidation process. This study reveals the importance of surface oxygen vacancies in improving the catalytic oxidation activity of catalysts, providing possibilities for the development of high-performance catalysts through atomic doping and reduction modification. [ABSTRACT FROM AUTHOR]

A potassium (K)-promoted Ru-based siliceous molecular sieve catalyst, K-nRu-MCM-41, was successfully synthesized via a hydrothermal method. The combined analysis of XRD, FT-IR and XPS data revealed that Ru exists in the framework of the molecular sieves as RuO2 species, leading to structural alterations. SEM and TEM images demonstrated that Ru doping disrupts the morphology of the molecular sieves, while K addition effectively preserves the original morphology and further enhances particle dispersion. The ammonia decomposition performance test indicated that K promotes the activity of the molecular sieve catalysts. At 450 °C and 12 000 mL gcat−1 h−1, K-4Ru-MCM-41 achieved 82.7% ammonia conversion and 253.6 mmol gRu−1 min−1 hydrogen production, respectively, which was a 7.6% increase in ammonia conversion compared with 4Ru-MCM-41. Furthermore, the K-4Ru-MCM-41 catalyst exhibited excellent reusability, maintaining its stable catalytic activity performance after 30 h. [ABSTRACT FROM AUTHOR]

Optimizing methanol reforming for hydrogen production is crucial, in which the regulation of the catalyst structure has a significant impact on improving catalytic activity. LaCoO3 perovskite is a promising catalyst for this application due to its tunable structure and exceptional thermal stability. This work reports the modulation of the active phase in the perovskite LaCo1−xCuxO3 (x = 0, 0.03, 0.06, 0.12) by annealing under a H2 atmosphere. The results of XPS, XRD, and H2-TPR reveal that Cu doping and hydrogen reduction can modify the chemical states of B-site elements. Consequently, the activity of methanol reforming for hydrogen production is considerably enhanced. The optimal performance for methanol hydrogen production observed in LaCo0.97Cu0.03O3 suffered from H2 reduction at 300 °C. This is due to the modulation of the active phase structure with appropriate redox pairs of Cu2+/Cu+, Co3+/Co2+ and O2−/Ov. This work offers valuable insights in the development of efficient catalysts for methanol reforming and hydrogen production. [ABSTRACT FROM AUTHOR]

Direct methanol fuel cells (DMFC) are a promising new energy source. However, the lack of high-performance and low-cost methanol oxidation electrocatalysts hinders their commercial application. Firstly, we successfully prepared NENU-5-derived molybdenum carbide material (Cu-MoC) via a co-precipitation and high-temperature carbonization method using a material composed of a copper-based metal–organic skeleton and a molybdenum-based carbide as the main body. Secondly, PtCu nano-alloy catalysts (Pt/Cu-MoC) were prepared using a unique, spontaneous single replacement reaction after metal–organic skeleton (MOF) carbonization. Through the synergistic effect between Pt and Cu and the strong interaction between Mo2C and PtCu, the electronic structure of the Pt is modified, the energy of the d-band center is reduced, electron exchange is accelerated, and catalytic activity is enhanced. Compared with a commercial Pt/C catalyst in alkaline environments, the Pt0.10/Cu-MoC catalyst has a better MOR catalytic activity (563.25 mA mgPt−1), which is 1.5 times higher than that of commercial Pt/C (376.67 mA mgPt−1). The Pt0.10/Cu-MoC catalyst has an onset potential for CO oxidation that is 16 mV lower than that of commercial Pt/C, indicating better resistance to CO poisoning. Exploring carbon materials derived from MOFs with excellent junction support and using them as carriers to prepare Pt-based catalysts is a practical and feasible approach. It provides a way to develop new Pt-based catalysts that perform efficient MOR. [ABSTRACT FROM AUTHOR]

Although lithium–sulfur (Li–S) batteries have attracted strong consideration regarding their fundamental mechanism and energy applications, the inferior cycling performance and low reaction rate caused by the "shuttling effect" and the sluggish reaction kinetics of lithium polysulfides (LiPSs) impede their practical application. In this work, graphitic C3N4 (g-C3N4) assembled with highly-dispersed nitrogen-containing carbon quantum dots (CQDs) is designed as a cooperative catalyst to accelerate the reaction kinetics of LiPS conversion, the precipitation of Li2S during discharging, and insoluble Li2S decomposition during the charging process. Meanwhile, the introduction of CQDs improves the conductivity of the g-C3N4 substrate, showing great significance for the construction of high-performance electrocatalysts. As a result, the as-obtained composite shows efficient adsorption and electrochemical conversion of LiPSs, and the Li–S batteries assembled with CQDs/g-C3N4 exhibit an initial specific capacity of 1300.0 mA h g−1 at the current density of 0.1C and retain 582.3 mA h g−1 after 200 cycles. The electrode with the modified composite displays a greater capacity contribution of Li2S precipitation (175.7 mA h g−1), indicating an enhanced catalytic activity of g-C3N4 decorated by CQDs. The rational design of CQDs/g-C3N4 as a sulfur host could be an effective strategy for developing high performance Li–S batteries. [ABSTRACT FROM AUTHOR]

The synthesis, characterization, and ring-opening polymerization (ROP) activity of a family of niobium and tantalum alkoxide catalysts was studied. The final catalysts are made in a two-step synthesis, first by reacting the desired homoleptic metal ethoxide with a phenolketoimine ligand to form a series of synthetic intermediates, followed by reaction with catechol to produce a catalytic platform with a single ethoxide initiator. By using two separate ligands, the electronic properties of the catalyst can be tuned, and the molecular weight of the polymer can be increased. It was found that synthetic intermediates adopted a mer geometry both in solution and in the solid state. This mer geometry was retained for the final catechol derivatives, however in one case, where catechol was substituted for 3-methoxycatechol, the molecule adopted a highly distorted fac geometry. Catalytic ROP activity of the synthetic intermediates and final catechol derivatives with ε-caprolactone was studied through a kinetic analysis. In all seven cases studied the reactions proceeded through the expected coordination–insertion mechanism, following pseudo first-order kinetics and increasing in Mn linearly vs. conversion. The single-initiator catechol derivatives increased the Mn by three times compared to that of the three-initiator synthetic intermediates with little decrease in the overall reaction rate. Both the nature of the ligand and metal were found to impact the rate of reaction in these systems. By switching from an electron donating ligand to an electron withdrawing ligand, the rate was found to nearly double. Tantalum species were faster than their niobium counterparts by ∼3 times in the synthetic intermediates and ∼1.5 times in the catechol derivatives. This observed periodicity supports recent literature findings in this area. [ABSTRACT FROM AUTHOR]

Tubular structured composites have attracted great interest in catalysis research owing to their void-confinement effects. In this work, we synthesized a pair of hollow N-doped carbon microtubes (NCMTs) with Fe3O4 nanoparticles (NPs) encapsulated inside NCMTs (Fe3O4@NCMTs) and supported outside NCMTs (NCMTs@Fe3O4) while keeping other structural features the same. The impact of structural effects on the catalytic activities was investigated by comparing a pair of hollow-structured nanocomposites. It was found that the Fe3O4@NCMTs possessed a higher peroxidase-like activity when compared with NCMTs@Fe3O4, demonstrating structural superiority of Fe3O4@NCMTs. Based on the excellent peroxidase-like catalytic activity and stability of Fe3O4@NCMTs, an ultra-sensitive colorimetric method was developed for the detection of H2O2 and GSH with detection limits of 0.15 μM and 0.49 μM, respectively, which has potential application value in biological sciences and biotechnology. [ABSTRACT FROM AUTHOR]

Three silyl [PSiP] pincer cobalt(II) chlorides 1–3 [(2-Ph2PC6H4)2MeSiCo(Cl)(PMe3)] (1), [(2-iPr2PC6H4)2MeSiCo(Cl)(PMe3)] (2) and [(2-Ph2PC6H4)2MeSiCo(Cl)(LSi:)] (LSi: = {PhC(NtBu)2}SiCl) (3) were synthesized and used as catalysts and their catalytic activity for dinitrogen silylation was studied. Among the three complexes complex 3 was new and was synthesized via the reaction of [PSiP] pincer preligand L1 with CoCl2 in the presence of chlorosilylene via Si–H bond cleavage. The molecular structure of 3 was determined by single crystal X-ray diffraction analysis. Compared to complex 1, complex 2 is the more effective catalyst for dinitrogen silylation and 363 equiv. of N(SiMe3)3 could be reached per Co atom. Further study indicates that using the silylene ligand in complex 3 instead of the PMe3 ligand in complex 1, the catalytic activity of 3 is lower than that of 1. The catalytic mechanism for this catalytic system is proposed with the support of experimental evidence. The [PSiP] pincer cobalt(I) dinitrogen complex was proposed as the active catalyst for dinitrogen silylation. [ABSTRACT FROM AUTHOR]

Diethyl carbonate (DEC) was synthesized from ethanol and ethyl carbamate (EC) over Mg–Y composite oxides with excellent yield. Mg–Y composite oxide calcined at 450 °C demonstrated excellent catalytic activity and 70.3% yield was obtained. Note that the production capacity of catalysts (PCC) reached 5987 mgDEC gcat−1 h−1 under the optimized conditions, which was far higher than that reported in previous literature reports. Furthermore, other carbamates such as methyl carbamate (MC) and butyl carbamate (BC) could be also successfully converted into the corresponding dialkyl carbonates. The catalyst could be easily recovered four times under identical conditions. The origin of the catalytic performance was studied using various characterization techniques, and the TPD results showed that the MgY-450 catalyst exhibited more accessible moderate and strong basic sites, which was beneficial to expressing excellent catalytic performance. [ABSTRACT FROM AUTHOR]

The development of carbon-based catalysts to substitute Pt-based catalysts for the oxygen reduction reaction is highly important for promoting their practical application in energy conversion. Herein, we prepare Zn, Fe and N-codoped porous carbon (Zn/Fe-NC-x) as a cathode catalyst via a facile one-step pyrolysis predesigned bimetallic zeolitic imidazole framework. Systematic electrochemical studies demonstrated that the synthesized Zn/Fe-NC-0.5 exhibits higher electrocatalytic activity towards the oxygen reduction reaction. In particular, Zn/Fe-NC-0.5 has a smaller charge transfer resistance, larger exchange current density, and much higher open circuit potential and mainly proceeds via an efficient four-electron pathway. A microbial fuel cell equipped with the synthesized catalyst exhibited the highest maximum power density of 1954 ± 20 mW m−2. In addition, the effects of the iron doping content on the oxygen reduction reaction performance and maximum power density were evaluated: a moderate Fe doping content plays a crucial role in improving the catalytic activity, and the synergistic effect of Zn, Fe and N codoping promotes cathodic performance. In brief, Zn/Fe-NC, which has the advantages of facile synthesis, environmental friendliness and excellent electrochemical activity, is a promising Pt-alternative catalyst for the oxygen reduction reaction in air-cathode microbial fuel cells. [ABSTRACT FROM AUTHOR]

Time-dependent crystallization evolution for synthesizing SAPO34 and SAPO-20 zeolites from a very active hydrogel is followed and reported where the XRD, FTIR, TGA/DTG, SEM/EDX, N2 adsorption–desorption and TPD-NH3 techniques are used. During the crystallization process, the hydrophobic trimethylbenzylammonium cation (BTMA+) has shown its ability as an effective structure-directing and pore filling agent. The resulting pure SAPO-34 and SAPO-20 show high crystallinity, where SAPO-34 exhibits higher porosity (393 m2 g−1, 0.24 cm3 g−1) and acidity (1.20 mmol g−1) than SAPO-20 (29 m2 g−1, 0.16 cm3 g−1, 0.02 mmol g−1), and these features are highly beneficial in the microwave-assisted ethanolysis of furfuryl alcohol. SAPO-34 shows outstanding catalytic activity (100% conversion, 72.5 ± 0.3% yield of ethyl levulinate) and its performance is much superior to that of SAPO-20 and other classical catalysts thanks to its medium pore size that induces molecular sieving effect. The spent SAPO-34 catalyst has high recyclability with stable activity, making it a superior and cost-effective catalyst for various selective petrochemical reactions. [ABSTRACT FROM AUTHOR]

The urgent need for effective and sustainable electrocatalytic nitrate reduction to mitigate global water contamination and foster fossil-free ammonia generation has driven extensive exploration of bimetallic non-noble metals in electrochemical applications. Herein, we present the development of an electrocatalyst, namely FeCu phosphide (Fe–CuP), which demonstrates high efficiency in the reduction of nitrate. The prepared samples exhibit exceptional catalytic activity in the electrocatalytic reduction of nitrate to NH3 in a neutral electrolyte. It is noteworthy that the Faraday efficiency reaches an impressive 89% at −1.5 V (vs. SCE), with NH3 yield of 0.6 mmol h−1 cm−2, surpassing the performance of the FeCu alloy. This superior performance can be attributed to the distinct surface morphology of the catalyst and its ability to facilitate rapid charge transfer, which is enhanced by the presence of phosphorus. Moreover, the Fe–CuP catalyst also demonstrates remarkable long-term stability making it an excellent candidate for practical applications. Thus, this work not only introduces a novel synthesis method for Fe–CuP but also establishes the efficacy of phosphorus in promoting nitrate reduction to NH3. These findings provide valuable insights into the advancement of electrocatalytic technologies for sustainable water treatment and ammonia synthesis. [ABSTRACT FROM AUTHOR]

This study introduces a novel catalyst designated as 2.6% Co/MXene, comprising cobalt (Co) nanoparticles supported by MXene. The synthesis of the 2.6% Co/MXene catalyst involved direct pyrolysis of a composite material, composed of a Co/Zn bimetal metal–organic framework and MXene. Catalytic transfer hydrogenation of functionalized nitro compounds into the corresponding formamides employed formic acid as both the hydrogen donor and formylation agent, demonstrating remarkable activity and selectivity. Control experiments validated that Co nanoparticles served as the active sites for reductive transformation. Systematic characterization and comprehensive experiments have confirmed that the superior catalytic performance of the 2.6% Co/MXene catalyst can be attributed to the uniform distribution of Co nanoparticles, a high density of basic sites, and the 3D porous architecture of the MXene support. Furthermore, the 2.6% Co/MXene catalyst exhibited excellent recyclability, preserving its catalytic activity and selectivity across four consecutive cycles. [ABSTRACT FROM AUTHOR]

Hydroformylation is one of the most important homogeneous reactions in industrial production. Herein, a density functional theory (DFT) method was employed to investigate two proposed reaction mechanisms of hydroformylation catalyzed by cationic cobalt(II) complexes, the carbonyl dissociative mechanism and the associative mechanism. The calculated results showed that the heterolytic H2 activation is the rate-determining step for both the dissociative mechanism and the associative mechanism, with energy barriers of 26.8 kcal mol−1 and 40.5 kcal mol−1, respectively. Meanwhile, the regioselectivity, the spin multiplicity of the catalyst and the substituent effects on the reaction were also investigated. The most stable cobalt(II) catalyst has a doublet state and the linear aldehyde is the dominant product. In addition, it was found that the energy barrier of the reaction decreased when the electron density of the Co center of the catalyst was increased by changing the ligand. The catalytic activity of the catalyst was proposed to be the best when the PEt2 group of the ligand is replaced by the P(tBu)2 group. This study might not only provide new insights for hydroformylation catalyzed by cobalt but also facilitate theory-guided design of novel transition metal catalysts for hydroformylation. [ABSTRACT FROM AUTHOR]

Single-atom catalysts (SACs) have attracted significant attention due to their unique electronic structure and extraordinary catalytic reaction activity. In this work, single-atom Au1/TiO2 catalysts were successfully prepared using cold plasma. Notably, plasma-treated TiO2 introduces a substantial number of oxygen vacancies, which played a confinement effect on gold atoms. Au1/TiO2 achieved a remarkable 67% degradation of RhB in just 120 minutes, surpassing the performance of AuNPs/TiO2 by 2.8 times. The high catalytic activity can be attributed to several factors. Firstly, plasma-treated TiO2 contained a higher density of oxygen vacancies and exhibited a narrower band gap, which improved light absorption and facilitated the anchoring of monoatomic Au on the catalyst surface. Additionally, the single-atom Au species exhibited stronger interactions with TiO2, enhancing light absorption and charge transfer capability. Simultaneously, the presence of SACs on the catalyst surface increased the number of active sites, promoting efficient separation of electron–hole pairs and consequently enhancing the photocatalytic degradation activity. Cold plasma technology offers a simple and environmentally friendly platform for the fabrication of SACs, opening up exciting possibilities for catalytic applications. [ABSTRACT FROM AUTHOR]

In the current study, morphologically different CdFe2O4 nanoparticles (NPs) have been synthesized by a facile thermal decomposition approach using Cd-Fe glycolates as precursors. Different morphologies (flake-like, raspberry, and hexagonal) of CdFe2O4 NPs were obtained by varying the reaction conditions. The CdFe2O4 NPs show morphology dependent magnetic properties and they exhibit superparamagnetism at 300 K and soft ferromagnetism at 5 K. The CdFe2O4 NPs exhibit peroxidase-like activity in the presence of H2O2, and their catalytic activity is better than that of horseradish peroxidase (HRP, a natural enzyme). The catalytic activity of CdFe2O4 NPs is affected by their morphology, particle size, surface area and the concentration of Fe3+ ions. [ABSTRACT FROM AUTHOR]

In aqueous pH 7 phosphate buffer, during controlled potential electrolysis (CPE) at -1.10 V vs. Ag|AgCl the literature square planar copper complex, [CuIILEt]BF4 (1), forms a heterogeneous deposit on the glassy carbon working electrode (GCWE) that is a stable and effective hydrogen evolution reaction (HER) electrocatalyst. Specifically, CPE for 20 hours using a small GCWE (A = 0.071 cm²) gave a turnover number (TON) of 364, with ongoing activity. During CPE the brownish-yellow colour of the working solution fades, and a deposit is observed on the small GCWE. Repeating this CPE experiment in a larger cell with a larger GCWE (A = 2.7 cm²), connected to a gas chromatograph, resulted in a TON of 2628 after 2.6 days, with FE = 93%, and with activity ongoing. After this CPE, the working solution had faded to nearly colourless, and visual inspection of the large GCWE showed a material had deposited on the surface. In a 'rinse and repeat test', this heterogeneous deposit was used for further CPE, in a freshly prepared working solution minus fresh catalyst, which resulted in similar ongoing HER activity to before, consistent with the surface deposited material being the active HER catalyst. EDS, PXRD and SEM analysis of this deposit shows that copper and oxygen are the main components present, most likely comprising copper and copper(I) oxide ((Cu2O)n) formed from 1. The use of 1 leads to a deposit that is more catalytically active than that formed when starting with a simple copper salt (control), likely due to it forming a more robustly attached deposit, which also enables the observed long-lived catalytic activity. [ABSTRACT FROM AUTHOR]

The synthesis of cyclic carbonates through cycloaddition reactions between epoxides and carbon dioxide (CO2) is an important industrial process. Metal-Organic Frameworks (MOFs) have functional and ordered pore structures, making them attractive catalysts for converting gas molecules into valuable products. One approach to enhance the catalytic activity of MOFs in CO2 cycloaddition reactions is to create open metal sites within MOFs. In this study, the amino-functionalized rare earth Gd-MOF (Gd-TPTC-NH2) and its ionic liquid composite catalysts (Gd-TPTC-NH-[BMIM]Br) were synthesized using 2'-amino-[1,1':4',1"-terphenyl]-3,3",5,5"-tetracarboxylic acid (H4TPTC-NH2) as the ligand. The catalytic performance of these two catalysts was observed in the cycloaddition reaction of CO2 and epoxides. Under the optimized reaction conditions, Gd-TPTC-NH-[BMIM]Br can effectively catalyze the cycloaddition reaction of a variety of epoxide substrates with good to excellent yields of cyclic carbonate products. Comparatively, epichlorohydrin and epibromohydrin, which possess halogen substituents, promote higher yields of cyclic carbonates due to the electron-withdrawing nature of Cl and Br substituents. Additionally, the Gd-TPTC-NH- [BMIM]Br catalyst demonstrated good recyclability and reproducibility, maintaining its catalytic activity without any changes in its structure or properties after five reuse cycles. [ABSTRACT FROM AUTHOR]

Phosphine ligands play a crucial role in homogeneous catalysis, allowing fine-tuning of the catalytic activity of various metals by modifying their structure. An ultimate challenge in this field is to reach controlled modulation of catalysis in situ, for which the development of phosphines capable of photoswitching between states with differential electronic properties has been proposed. To magnify this lightinduced behavior, in this work we describe a novel phosphine ligand incorporating two dithienylethene photoswitchable moieties tethered to the same phosphorus atom. Double photoisomerization was observed for this ligand, which remains unhindered upon gold(I) complexation. As a result, the preparation of a fully ring-closed phosphine isomer was accomplished, for which amplified variation of phosphorus electron density was verified both experimentally and by computational calculations. Accordingly, the presented molecular design based on multiphotochromic phosphines could open new ways for preparing enhanced photoswitchable catalytic systems. [ABSTRACT FROM AUTHOR]

Selective CO2 adsorption and catalysis conversion of CO2 to high value-added chemicals not only gives an effective way to reduce the concentration of CO2 but also provides the precursors for industrial manufacturing of chemicals and fuels. With well-defined frameworks, flexible modifiability, and permanent porosity, metal–organic frameworks (MOFs) can be the ideal platforms for CO2 utilization applications. In this work, a copper functionalized-zirconium MOF, denoted Zr-CPB-Cu (CPB = 1,2,3,4,5,6-hexakis(4-carboxyphenyl)-benzene), was successfully produced via post-metalation of copper(II) ions into a presynthesized Zr-CPB MOF. The bimetallic Zr-CPB-Cu containing two open metal sites (Zr4+ and Cu2+), polarized groups (e.g., uncoordinated –COOH, monodentate carboxylates, and acetate anions), accessible triangular channels, and permanent porosity (SBET = 420 m2 g−1) revealed outstanding selective CO2 adsorption and catalytic activity for the oxidative carboxylation of CO2 and olefins. As a proof of concept, the Zr-CPB-Cu showed higher low-pressure capacities of CO2, CH4, and N2 at room temperature and larger CO2 selectivities over N2 and CH4 than those of the parent Zr-CPB. As for catalysis of CO2 conversion, the Zr-CPB-Cu catalyst exhibited exceptional performance in direct synthesis of styrene carbonate from styrene and CO2 with 97% conversion of styrene, and 92% yield of styrene carbonate in the presence of anhydrous TBHP oxidant and under mild conditions (1 atm of CO2, 80 °C, and 12 h). Notably, the catalytic activity of Zr-CPB-Cu outperformed that of the parent Zr-CPB and other MOFs, and the recovered Zr-CPB-Cu can be reused up to six times without considerable reduction in catalytic activity. Our result envisaged an effective approach for the elaboration of MOFs as efficient heterogeneous catalysts for CO2 separation and catalytic conversion of CO2. [ABSTRACT FROM AUTHOR]

Two Ni-inserted polyoxotantalates, K5.5Na2H0.5[Ni(H2O)2{NiTa10O30(OH)2}]·21H2O (1) and K6Na4[Ni(en){NiTa10O32}]·22H2O (2, en = ethanediamine), were synthesized in this work. Crystallographic data analyses reveal that 1 and 2 have similar configurations. A minor difference between these two structures is that the {Ni(H2O)2} unit in 1 is replaced by {Ni(en)} unit in 2. Notably, the other Ni in 1 and 2 is located as a heteroatom at the center of the {Ta10} unit, which is reported in POTas for the first time. Moreover, 2 exhibits excellent catalytic performance in transesterification reactions in a preliminary exploration of the catalytic ability of the synthesized POTas. [ABSTRACT FROM AUTHOR]

This manuscript describes the synthesis of a triazolyl-pyridine-based phosphine, N-((diphenylphosphaneyl)methyl)-N-methyl-6-(1-phenyl-1H-1,2,3-triazol-4-yl)pyridin-2-amine, [2,6-{(PPh2)CH2N(Me)(C5H3N)(C2HN3C6H5)}] (1) (here onwards referred to as PNN) and its cationic and neutral MnI complexes and catalytic applications. The reaction of 1 with Mn(CO)5Br afforded a cationic complex [Mn(CO)3(PNN)]Br (2), which is highly stable in solid state, but in solution it gradually loses one of the CO groups to form a neutral complex [Mn(CO)2(PNN)Br] (3). Complex 2 on treatment with AgBF4 also yielded a cationic complex [Mn(CO)3(PNN)]BF4 (4). These complexes efficiently promoted the synthesis of quinoline derivatives via acceptor-less dehydrogenative coupling of 2-aminobenzyl alcohol and ketones, with complex 3 showing the highest activity with a very low catalyst loading (0.03 mol%) at 110 °C. Complex 3 (0.5 mol%) also showed excellent catalytic activity in the transfer hydrogenation of ketones and aldehydes to form respective secondary and primary alcohols. [ABSTRACT FROM AUTHOR]

A set of mononuclear cobalt(III) octahedral complexes {[Co(LH)(acac)] (Co-1H), [Co(LBr)(acac)] (Co-1Br), and [Co(LNO2)(acac)] (Co-1NO2)} were synthesized using new-generation N/O donors, maleonitrile-tethered, tetradentate heteroscorpionate half-reduced Schiff base ligands, 2-((E)-2-hydroxybenzylideneamino)-3-(pyridin-2-ylmethylamino)maleonitrile (H2LH), 2-((E)-(5-bromo-2-hydroxybenzylidene)amino)-3-((pyridin-2-ylmethyl)amino)maleonitrile (H2LBr), and 2-((E)-2-hydroxy-5-nitrobenzylideneamino)-3-(pyridin-2-ylmethylamino)maleonitrile (H2LNO2). All the compounds were well characterized spectroscopically and structurally. The non-covalent interactions present in the lattice of Co-complexes were studied in detail to explain the molecular architecture using the Hirshfeld surface (HS) analysis. The catalytic activity of CO2 fixation towards epoxides under mild and solvent-free conditions was demonstrated. The synthesized complexes are catalysts that are well-active towards the CO2 activation under ambient conditions, whereas most of the reported catalysts require harsh conditions. [ABSTRACT FROM AUTHOR]

Subphthalocyanines (SubPcs) have emerged as promising organic dyes for the development of efficient artificial photosynthetic devices, offering intense absorption in the visible region along with excellent charge transport properties. In this study, four novel SubPc derivatives containing carboxylic acid and various peripheral substituents were synthesized as a panchromatic photosensitizer to prepare an efficient and stable TiO2-based photocatalytic system for co-catalyst-free photocatalytic hydrogen evolution. To compare the influence of the nature of the peripheral substituents on photocatalytic activity, SubPc derivatives (coded as SubPc 1–4) were decorated with substituents having different electron-donating capabilities, such as alkyl thio, benzodioxin, amine, and iodo units, respectively. Photocatalytic activities were examined in the presence of TEOA as a sacrificial agent under irradiation with λ > 400 nm without co-catalyst loading. SubPc 1/TiO2 shows the best photocatalytic activity among the SubPc-sensitized photocatalysts, with a hydrogen evolution rate of 0.176 mmol h−1. While the activity of all four SubPc-based photocatalysts increased significantly after 24 h irradiation, notably, SubPc 1/TiO2 exhibited remarkable catalytic activity, achieving a hydrogen evolution rate of 6.017 mmol with a high turnover number (TON) value of 12 279 for hydrogen production. This study highlights the potential of SubPc-based sensitizers for co-catalyst-free photocatalytic H2 production and offers valuable insights into the impact of peripheral units in SubPc/TiO2-based photocatalytic systems. [ABSTRACT FROM AUTHOR]

Alkaline earth metal (Mg2+, Ca2+, Sr2+, and Ba2+)-doped CeO2 nanocatalysts have been prepared by the successive co-precipitation and calcination method. The basicity and quantities of basic sites of alkaline earth metal-doped CeO2 nanocatalysts are remarkably influenced by the type and content of doped alkaline earth metal cations. The number of weak basic sites, Ce3+ cations, and oxygen vacancies of the doped CeO2 nanocatalysts are obviously improved when the ionic radii of alkaline earth metal cations are comparable to that of Ce4+. Catalytic activities of the doped CeO2 nanocatalysts in the synthesis of dimethyl carbonate through the reaction between methanol and CO2 increase with the increase in weak basic sites and oxygen vacancies. When the Mg0.05Ce0.95O2 nanocatalyst with larger amounts of both weak basic sites and oxygen vacancies catalyzed the reaction with a catalyst/methanol mass ratio of 1.0 : 50.0 at 4.0 MPa of CO2 and 140 °C for 4 h, the yield of dimethyl carbonate was 3.95 mmol gcat−1, which is 1.31 times that obtained on the sole CeO2 catalyst. The doping of the CeO2 nanocatalyst with alkaline earth metal obviously reduces the catalytic reaction activation energy. [ABSTRACT FROM AUTHOR]

Mesoporous Fe3O4-loaded silver nanocomposites (Fe3O4@Ag) were simply fabricated as bi-functional nanozymes for the catalysis-based detection and removal of Hg2+ ions. It was found that the as-prepared magnetic Fe3O4@Ag could display peroxidase-like catalysis activity that could be rationally enhanced in the presence of Hg2+ ions. To our surprise, the shell of the Ag element may decrease the catalysis of the Fe3O4 to some degree. However, the Ag particles could serve as the probes for specifically recognizing Hg2+ ions and trigger increased catalysis through the formation of Ag–Hg alloys, with a decreased signal background. A high-throughput colorimetric analytical method was thereby developed based on the Fe3O4@Ag catalysis for probing Hg2+ ions in the muscles of fish by using 96-well plates, at linear Hg2+ concentrations ranging from 0.010 to 2.5 mg kg−1. Moreover, the developed colorimetric analytical method was applied to evaluate Hg2+ levels in muscle samples of different kinds of fish. Unexpectedly, an obvious difference of Hg2+ levels in muscles of four kinds of fish was discovered, with the order of snakehead (Ophicephalus argus) > largemouth bass (Micropterus salmoides) > crucian carp (Carassius auratus) > silver carp (Hypophthalmichthys molitrix), where the carnivorous fish showed higher Hg2+ levels than the omnivorous or plant-based ones. Moreover, the as-fabricated Fe3O4@Ag adsorbents with their large specific surface area and high environmental robustness could exhibit efficient Hg2+ adsorption with capacities of up to 397.60 mg g−1. A removal efficiency of 99.40% can also be expected for Hg2+ ions from wastewater, with the magnet-aided recycling of Fe3O4@Ag adsorbents. Such an Fe3O4@Ag-based colorimetric analysis and removal strategy for Hg2+ ions should find wide applications in the fields of aquatic food safety, environmental monitoring, and clinical diagnostics of Hg-poisoning diseases. [ABSTRACT FROM AUTHOR]

Herein, we report an efficient and straightforward approach for the synthesis of N-alkylated aminoquinoline derivatives by recyclable Cd-containing coordination polymer-catalyzed reactions of aminoquinolines with primary alcohols via the borrowing hydrogen strategy. In this work, a new type of coordination polymer [Cd(CIA)(phen)2(H2O)]n was successfully designed and fabricated. The molecular structure was corroborated by single-crystal X-ray diffraction and fully characterized by PXRD, FT-IR, TGA, and XPS. Importantly, this polymer revealed high catalytic activity for the N-alkylation reaction of 2-aminoquinoline and 8-aminoquinoline with inexpensive and low-toxicity alcohols as alkylating agents in excellent yields up to 95%. Interestingly, the present synthetic protocol was successfully applied for the gram-level synthesis of several biologically active compounds. In addition, several control reactions were carried out to investigate the possible mechanisms of this transformation. Finally, recycling experiments indicated that the cadmium coordination polymer showed good recovery performance for borrowing hydrogen reactions. [ABSTRACT FROM AUTHOR]

We investigate Ti(NEt2)4 supported on silica dehydroxylated at 700 °C as an easily accessible pre-catalyst for oxo/imido heterometathesis reactions. Being activated with TolNH2, the supported Ti amide (≡SiO)Ti(NEt2)3 (1) demonstrates catalytic activity in the imidation of ketones with N-sulfinylamines comparable with the most active previously described well-defined imido catalyst (≡SiO)Ti(＝NtBu)(Me2Pyr)(py)2 (2) (Me2Pyr = 2,5-dimethylpyrrolyl), which implies the in situ formation of surface imido species in this system. The materials obtained via treatment of 1 with anilines (TolNH2 (1a) and p-MeOC6H415NH2 (1b)) were studied with IR, EA and 1H, 13C, 15N and 2D solid-state NMR, although the proposed imido intermediate has not been detected, pointing towards tris-amides (≡SiO)Ti(NHC6H4X)3 (X = Me, OMe) being the major surface species in the isolated materials 1a and 1b. The system 1/TolNH2 was tested in a range of imidation reactions and demonstrated excellent performance for express high-yielding preparation of ketimines, formamidines, lactone imidates and sulfurdiimines, making it a convenient alternative to the well-defined supported Ti imido catalysts. [ABSTRACT FROM AUTHOR]

Electronic modulation is of great importance in an attempt to enhance the catalytic activity of electrocatalysts towards the oxygen evolution reaction (OER), which dominates the energy efficiency of water splitting. Here, a facile and reliable strategy is reported based on the specific synergistic effects of the combination of early and late transition metals. The OER activity of a prototypical bimetallic NiFe-MOF was greatly promoted by introduction of a Cr ion dopant, and the as-prepared Cr-NiFe-MOF needed a low overpotential of only 242 mV to deliver a current density of 100 mA cm−2 with excellent stability. Detailed analyses revealed that Cr replaced the position of Ni in the NiFe-MOF and adjusted the electronic structure of nearby Fe sites, allowing the d-band center to shift down to efficiently regulate the adsorption behavior of key intermediates, which endowed the Cr-neighboring Fe sites with a lowered energy barrier for the OER. This work presents a strategy of early-and-late transition metal combination to provide new pathways for efficient water splitting catalyst development. [ABSTRACT FROM AUTHOR]

The biorenewable carbohydrate-derived rigid building block of isosorbide (ISB) has demonstrated potential in high-performance polymer materials; however, a controllable eco-friendly preparation technology is not yet available. For this purpose, a sustainable strategy to synthesize ISB-based polycarbonate (PIC) has been established by adopting the CO2-based compound dimethyl carbonate (DMC) as a monomer and ionic liquids (ILs) as metal-free catalysts. The molecular weight of PICs can be readily controlled by varying the cation structure of IL catalysts. Control experiments, density functional theory (DFT) calculations, and Kamlet–Taft solvent parameters indicated that the H-bond donor/acceptor (HBD/HBA) ability of IL catalysts played a dominant role in regulating catalytic activity. PIC molecular weight can be modulated by modifying the inherent difference in reactivity of endo-OH and exo-OH in ISB, wherein the chain length or substituent group of cations can regulate the HBD/HBA ability of IL catalysts and anions can specifically activate the carbonyl carbon of DMC. The experimental results revealed that a task-specific [Pmim][OAc] catalyst exhibited the highest catalytic activity, which is attributed to its significant role in considerably lowering the disparity in reactivity between endo-OH and exo-OH. For this DMC route, the [Pmim][OAc] catalyst offered a PIC with the highest molecular weight of 57 200 g mol−1 reported to date. Furthermore, a well-supported polymerization mechanism was proposed, in which [Rmim][OAc]'s anion–cation synergistically catalyzed ISB and DMC to prepare PIC. Our findings offer a clear pathway for designing efficient metal-free catalysts to enable the sustainable synthesis of high molecular weight PICs, thus expediting the industrialization of the DMC route. [ABSTRACT FROM AUTHOR]

Gold nanoparticles (AuNPs) with a high specific surface area show efficient activity for the reduction of nitroaromatics. In this study, single-stranded DNA chains (ssDNA, T30, C30 or A30) were used as templates to mediate the formation of AuNPs, and the results demonstrated that the morphologies of the C30-AuNPs or A30-AuNPs had more abundant irregular features than the T30-AuNPs. The catalytic properties and applications of the C30-AuNPs were systematically examined using a reaction model for the reduction of 4-nitrophenol by NaBH4. The effect of different temperatures and pH values on the catalytic activity of C30-AuNPs have been investigated. The C30-AuNPs showed the highest catalytic activity (rate constant kapp = 0.2221 min−1) for the reduction of 4-NP at 35 °C and pH = 7. The conversion of 4-NP to 4-AP using C30-AuNPs followed the Langmuir–Hinshelwood mechanism, which was explained by the principle of promoting electron transfer, i.e. the surface of C30-AuNPs is rich in active sites that promote the process of electron transfer from BH4− to 4-NP, completing the conversion of 4-nitrophenol to 4-aminophenol. Furthermore, the results confirmed that C30-AuNPs were versatile for catalyzing isomers of 4-NP and azo dyes, such as 2-NP, 3-NP, MO, CR and EBT. The results offer new insights into the construction of Au-based catalysts for efficiently removing environmental pollutants. [ABSTRACT FROM AUTHOR]

Carbon dots with good photoelectric properties are usually used as photocatalysts and electrocatalysts, but the good catalytic performance of carbon dots as nanomaterials for thermal catalysis is ignored. Herein, the application of novel efficient catalysts based on carbon dots for the transformation of carbon dioxide (CO2) to carbonates under solvent-free conditions is described. Carbon dots containing carboxyl, hydroxyl, and amine groups were prepared by a microwave technique and employed together with KI, which showed exceptional catalytic activity in the cycloaddition of carbon dioxide with different epoxides. In addition, the catalyst was easily reusable and had stable recyclability. And the catalyst displayed outstanding catalytic performance due to the synergistic effect of carboxyl (–COOH), hydroxyl (–OH), and amine (–NH) groups. [ABSTRACT FROM AUTHOR]

A series of low-cost Lewis acidic deep eutectic solvents (DESs) was synthesized and applied for the first time for catalyzing the polymerization of α-pinene to produce terpene resins. The DES catalyst of [AlCl3]3[CPL] prepared via the self-assembly of AlCl3 and caprolactam (CPL) exhibited the highest catalytic activity, and polymerization conditions were optimized by a single-factor method: 15 g α-pinene, 3 g catalyst, 1 g initiator, −5 °C reaction temperature, and 4 h reaction time. Under these conditions, the softening point of the terpene resin reached (annular spheroid method) 118.3 °C, the acid value was 0.22 mg KOH g−1, and the depth of color (Fe–Co method) was 5. The structure of [AlCl3]3[CPL] was characterized using FT-IR, 1H-NMR, and UV-vis spectroscopy. GPC measure showed that the number-average molecular weight of the terpene resin was 510, the weight-average molecular weight was 776, and the polydispersity index was 1.523. TG results indicated that the terpene resin had favorable thermal stability. After the reaction, the product and the catalyst could be automatically divided into two phases, which was beneficial for recycling the catalyst. The results revealed that [AlCl3]3[CPL] exhibited good recyclability. [ABSTRACT FROM AUTHOR]

As important building blocks in natural products and organic synthesis, thioethers have a wide range of potential applications. Herein, polyoxometalate-based ionic liquids (POM-ILs-SO3H) derived from N-alkyl imidazole were synthesized and used for the first time for the thiolation of alcohols to construct C–S bonds in a series of benzyl thioethers. This type of POM-ILs-SO3H catalyst exhibited high catalytic activity, providing up to 98% yield of thioether within 1 h at 70 °C. The alkyl chain length of the imidazole had a certain effect on the solubility of the POM-ILs-SO3H catalysts in the reaction solvent, and then affected their catalytic activity. The catalytic system had a wide substrate scope and was suitable for the reaction of tertiary and secondary benzyl alcohols with thiophenols or cycloalkyl thiols. In particular, [PIMPS]3PW12O40 (PIM = 1-propylimidazole, PS = propane sulfonate) as a reversible phase transformation-type catalyst, combining the advantages of homogeneous and heterogeneous catalysts, exhibited high activity and good recyclability with only a slight decrease in the yield after five runs. Additionally, a carbocation mechanism was proposed for the thiolation reaction of alcohols. [ABSTRACT FROM AUTHOR]

Hydrazine-assisted electrochemical water splitting is an important avenue toward low cost and sustainable hydrogen production, which can significantly reduce the voltage of electrochemical water splitting. Herein, we took a simple approach to fabricate NiFeP nanosheet arrays on nickel foam (NiFeP/NF), which exhibit superior electrocatalytic activity for the hydrogen evolution reaction (HER) and the hydrazine oxidation reaction (HzOR). Our investigations revealed that the excellent electrocatalytic activity of NiFeP/NF mainly arises from the bimetallic synergistic effect, abundant electrocatalytically active sites facilitated by the porous nanosheet morphology, high intrinsic conductivity of NiFeP/NF and strong NiFeP–NF adhesion. We assembled a hydrazine-boosted electrochemical water splitting cell using NiFeP/NF as a bifunctional catalyst for both electrodes, and the overall hydrazine splitting (OHzS) exhibits a considerably low overpotential (100 mV at 10 mA cm−2), and is stable for 40 h continuous electrolysis in a 1 M KOH + 0.5 M N2H4 electrolyte. When it is applied to hydrogen production by seawater electrolysis, its catalytic activity shows strong tolerance. This work provides a promising approach for low cost, high-efficiency and stable hydrogen production based on hydrazine-assisted electrolytic seawater splitting for future applications. [ABSTRACT FROM AUTHOR]

The electrochemical reduction of CO2 to HCOOH is considered one of the most appealing routes to alleviate the energy crisis and close the anthropogenic CO2 cycle. However, it remains challenging to develop electrocatalysts with high activity and selectivity towards HCOOH in a wide potential window. In this regard, Ag/Bi2O2CO3 was prepared by an in situ electrochemical transformation from Ag/Bi2O3. The Ag/Bi2O2CO3 catalyst achieves a faradaic efficiency (FE) of over 90% for HCOOH in a wide potential window between −0.8 V and −1.3 V versus the reversible hydrogen electrode (RHE). Moreover, a maximum FE of 95.8% and a current density of 15.3 mA cm−2 were achieved at a low applied potential of −1.1 V. Density functional theory (DFT) calculations prove that the high catalytic activity of Ag/Bi2O2CO3 is ascribed to the fact that Ag can regulate the electronic structure of Bi, thus facilitating the adsorption of *OCHO and hindering the adsorption of *COOH. This work expands the in situ electrochemical derivatization strategy for the preparation of electrocatalysts. [ABSTRACT FROM AUTHOR]

Monodispersed and faceted Bi2Fe4O9 micro-cuboid crystals with a mullite-type structure have been successfully synthesized by a facile hydrothermal method. The single crystalline Bi2Fe4O9 micro-cuboids exhibited a length of 10–20 μm and a square cross-section with a side length of 1–2 μm. The preferential growth of the Bi2Fe4O9 micro-cuboid crystals has been determined to be along 〈001〉 with the dominant (110) and (−110) facets enclosed. These micro-cuboid crystals were probably formed by a dissolution–recrystallization mechanism, where a phase transition from irregular-shaped sillenite Bi25FeO40 agglomerates to perovskite BiFeO3 microspheres occurred and finally resulted in the micro-cuboid crystals. More interestingly, these micro-cuboids demonstrated a remarkable photo-Fenton catalytic degradation activity towards RhB under visible light irradiation (λ > 400 nm). 90.2% RhB decomposition at 120 min can be achieved and the corresponding apparent rate constant is 0.0175 min−1, 11.67 times and 3.65 times larger than that of Fenton-like oxidation and pure photocatalysis, respectively. The as-prepared Bi2Fe4O9 micro-cuboid crystals also showed intriguing morphology-dependent ferromagnetism at room temperature, possibly allowing the magnetic recollection and reuse of Bi2Fe4O9 samples as well as their magnetic-field-mediated photocatalytic performances. [ABSTRACT FROM AUTHOR]

Replacing expensive platinum in electrocatalytic materials by cheaper and readily available alternatives is a paramount task in hydrogen-based energetics. In this study, we synthesize a copper–palladium nanostructured catalyst with lowered palladium content on a reduced graphene oxide support (RGO/CuPd), and compare its catalytic activity in the oxygen reduction reaction (ORR) against the monometallic analogues RGO/Cu and RGO/Pd. The products are fully characterized by a set of instrumental methods, including TGA, XRD, XPS, and TEM. The chemical form of metals in all the three composite materials is different. In RGO/Cu, copper exists in the form of single Cu2+ ions chemically bound to the RGO surface. In RGO/Pd, palladium forms metallic nanoparticles. In RGO/CuPd, part of Cu2+ covers the RGO surface, similar to RGO/Cu, but another part forms alloyed nanoparticles with Pd. The catalytic properties of the prepared materials are tested by CV, chronoamperometry, and the actual membrane electrode assemblies. Interestingly, even noble-atom-free RGO/Cu demonstrated catalytic activity toward the ORR. The most efficient material was still pure palladium-based RGO/Pd. However, replacing half of expensive Pd by Cu in RGO/CuPd only slightly lowered the catalyst efficiency; the maximum current densities for RGO/CuPd and RGO/Pd were respectively 124 and 136 mA cm−2, and the power densities were respectively 55.8 and 59.6 mW cm−2. The discovered synergistic effect between Cu and Pd opens the route for developing platinum-free, low-noble-metal-content catalytic systems for the ORR. [ABSTRACT FROM AUTHOR]

The catalytic activity of cyclobutadiene rhodium complexes was investigated in various transformations of alkynes. Complexes [Rh(C4Et4)Hal]n (at 1 mol% loading) were found to promote hydrosilylation of 1-octyne selectively giving 1-Z-, 1-E-, or 2-Et3Si-1-octene depending on the nature of the halide ligand and the presence of additional ligand PPh3. Complex [Rh(C4Et4)(p-xylene)]+ (1 mol%) also efficiently catalyzed the polymerization of phenylacetylene. At the same time, we found that various cyclobutadiene rhodium complexes do not catalyze the Diels–Alder reaction, alkyne hydration, and 1,4-addition of boronic acids to cyclohexanone. New complexes [Rh(C4Et4)(PPh3)2]BF4 and [Rh(C4Et4)(C10H8)]PF6 were also synthesized and their structures were established by X-ray diffraction. [ABSTRACT FROM AUTHOR]

Porous nanoparticles integrating the advantages of porosity and structural coherence typically possess numerous active sites confined on their surfaces. In this study, porous Co3O4, Fe2O3 and Fe3O4 nanoparticles are synthesised by one-step pyrolysis from metal–organic frameworks (MIL-101 (Fe) and ZIF-67 (Co)) to test the performance of CO oxidation. The prepared porous nanoparticles have uniform and stable porous structures without obvious shrinkage and structural collapse. The best catalytic performance was achieved by the porous Co3O4 nanoparticles, which reached 100% CO conversion at 130 °C without any decay in catalytic activity after 48 h of reaction. DRIFTS results present the mechanism of the CO oxidation by porous Co3O4 nanoparticle catalysis. The excellent catalytic activity of the porous Co3O4 nanoparticles is related to the large specific surface area and surface oxygen vacancies. This work provides a design approach for synthesizing other porous metal oxide nanoparticles and has reference value in the field of CO oxidation. [ABSTRACT FROM AUTHOR]

The distribution of gold nanoparticles (AuNPs) on the surface of a metal–organic framework (MOF) plays a crucial role in the catalytic performance of MOF-AuNP composites. This study describes how the physical adsorption (PH@AuNPs-on-U) and chemical modification of AuNPs on the surface of UiO-66-NH2 (U) affect the composites' catalytic efficiency. After 2-vinyl-4,4-dimethyl-2-oxazolin-5-one (VD) linked to poly(N-2-hydroxypropyl methacrylamide) (PH) with U (UVD-PH), UVD-PH@AuNPs composites were constructed with PH as the capping and reducing reagent. The composites exhibited higher peroxidase (POD)-like activity than PH@AuNPs-on-U for oxidising 3,3′5,5′-tetramethylbenzidine (TMB) with H2O2. The approach demonstrated that the proposed composite-based nanozymes could significantly enhance their catalytic activity and had a highly uniform distribution of PH@AuNPs on the surface of UVD. An assay with the nanozymes for visual detection of homocysteine (Hcy) was developed, displaying a good linear relationship (R2 = 0.998) ranging from 3.34 μM to 30.0 μM and a detection of limit of 0.3 μM. Additionally, the UVD-PH@AuNPs-TMB-H2O2 system successfully monitored serum Hcy after intraperitoneal injection in rats. This study paves a new way for developing MOF-AuNPs with highly uniform surface distribution of polymer@AuNPs to boost its catalytic activity and to detect drugs in real bio-samples. [ABSTRACT FROM AUTHOR]

There are few literature reports on using precatalysts based on ruthenium(II / III) ions in the polymerization of olefins. Therefore, a new coordination compound was designed based on ruthenium(III) ion and 2-phenylpyridine. The resulting monocrystal was characterized by X-ray diffraction (XRD), solid-state (photo)IR spectroscopy, scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The new ruthenium(III) complex compound was used as a precatalyst in the oligomerization reactions of ethylene, 2-propen-1-ol, 2-chloro-2-propen-1-ol, 3-butene-2-ol and 2,3-dibromo-2-propen-1-ol with methylaluminoxane and ethylaluminium dichloride as activators. The catalytic activity of the newly discovered ruthenium(III) complex compound ranges from 159.5 (for 2-chloro-2-propen-1-ol) to 755.6 (for ethylene) g mmol−1 h−1 bar−1, indicating that it is a chemical compound with high catalytic activity. In addition, the oligomerization reaction products were subjected to physicochemical characterization, using BET (Brunauer–Emmett–Teller isotherm), mass spectrometry (MALDI-TOF-MS), Fourier transform infrared (FT-IR) spectroscopy, NMR, TGA, differential scanning calorimetry (DSC), and the morphology of the porous polymeric materials was investigated by SEM. The distinguishing feature of the obtained precatalyst is its high catalytic activity under mild reaction conditions, a rare phenomenon. Compared with other precatalysts, it is the most active ruthenium(II / III) ion-based catalytic material used in oligo- and polymerization reactions of ethylene. [ABSTRACT FROM AUTHOR]

Oxidative desulfurization is an appealing alternative technology to eliminate organic sulfides in fuel oil in response to environmental and economic requirements. The supported metal oxide catalysts generally possess low catalytic activity and/or deactivation due to the loss and sintering of their metal oxides during the reaction or removal of carbon deposition at elevated temperature. In this work, beta zeolite-fixed MoO3 (MoO3@beta) was hydrothermally synthesized via structural reconstruction. A series of characterizations confirmed that MoO3 nanoparticles with an ultrasmall crystal size of 1.5–2.5 nm were fixed into the beta zeolite. Owing to the small particle size of MoO3, the MoO3@beta material exhibited nearly three times higher catalytic activity, weight-based space–time-yield, and active site-based turnover frequency than an impregnated MoO3/beta sample with MoO3 in an extra-framework position during the process of oxidative desulfurization with the oxidant H2O2. As for the oxidant molecular O2, MoO3@beta also possessed superior catalytic activity in a deep eutectic solvent under mild reaction conditions of 90 °C and ambient pressure, regardless of the model oil or actual fuel oil. Besides, excellent reusability was observed for the MoO3@beta catalyst via the elimination of carbon deposition through simple calcination, resulting from its unique feature to resist the loss and sintering of MoO3 fixed in the zeolite. More importantly, the catalytic mechanism of MoO3@beta was also revealed. This work opens a new avenue for effectively synthesizing zeolite-fixed metal oxide and establishing a green heterogeneous reaction system for catalytic oxidations. [ABSTRACT FROM AUTHOR]

There is a vital need to develop cheaper catalysts as alternatives to expensive platinum, gold, and palladium precious-metal catalysts and to overcome the limitations caused by carbon monoxide poisoning in direct methanol fuel cells (DMFCs). In the present work, a single-step hydrothermal method has been utilized for the synthesis of a NiO–CuO–ZnO(NCZ) ternary mixed metal oxide composite and binary NiO–CuO (NC), CuO–ZnO (CZ), and NiO–ZnO (NZ) composites for optical and fuel cell applications. UV spectroscopy analysis reveals energy band gaps of binary and ternary mixed metal oxides of Ni, Cu, and Zn via Tauc plots. In a basic medium (0.5 M NaOH) at a potential of +0.29 V (vs. Ag‖AgCl), the NCZ ternary mixed metal oxide composite displayed 1.34-, 2- and 3.9-times greater methanol (MeOH) oxidation activity compared to binary NiO–ZnO (NZ) (5.8 mA cm−2), CuO–ZnO (CZ) (3.9 mA cm−2) and NiO–CuO (NC) (2.0 mA cm−2) composites, respectively. The tertiary metal oxide catalyst has a high oxidation activity due to the synergistic effect of metal oxides in NCZ. NiO provides active sites for the electrooxidation of methanol, while CuO and ZnO contribute to the excellent chemical and mechanical stability of the prepared electrocatalyst. Various electrochemical features of the NCZ electrode, like surface area, durability and peak current values, are found to be good in an alkaline medium as compared to an acidic medium. The charge transfer resistance, electron recombination lifetime, and peak frequency values are determined using electrochemical impedance spectroscopy (EIS) and Nyquist and Bode plots. The NCZ electrocatalyst exhibits superior performance to binary catalysts, making it a cost-effective, efficient, non-noble metal-containing, and eco-friendly candidate for energy and optoelectronic devices. [ABSTRACT FROM AUTHOR]

The practical application of CO2 electroreduction to CO driven by renewable electricity should simultaneously meet the requirements of low overpotential, high CO faradaic efficiency (FE), and low cost. Herein, a new strategy is reported to construct a porous nanoflower Ni–Al NC catalyst with excellent catalytic activity via p–d orbital hybridization of Al and Ni. The optimized Ni–Al NC catalyst exhibits an outstanding CO2 electroreduction activity with the maximum CO FE of 98%, low onset potential of −0.5 V vs. RHE, and wide FECO plateau (>90% from −0.7 to −1.0 V vs. RHE), showing great promise for practical applications. The experimental results showed that the p–d hybrid Ni–Al NC catalyst not only enriched its reaction sites but also withstood potential changes in the highly selective reduction of CO2 to CO. This study provides a catalyst design strategy for the efficient electrocatalytic reduction of CO2 to CO under varying potentials. [ABSTRACT FROM AUTHOR]

Methanol steam reforming is considered as a potential hydrogen supply pathway, and Cu-based catalysts are commonly used catalysts for this reaction. A series of CZAT-x catalysts were synthesized, which are derived from Cu/ZnO/Al2O3 catalysts by modifying the method of introducing TiO2 in this study. Characterization techniques (BET, XRF, XRD, H2-TPR, N2O chemisorption, TEM, and XPS) revealed that the mode of TiO2 introduction primarily influences surface Cu dispersion, reducibility and Cu–Ti interaction, subsequently affecting CZAT-x catalysts' catalytic activity and thermal stability in methanol steam reforming. The TiO2-doped catalyst prepared through solvent-assisted ball milling demonstrated the highest activity. The complete conversion of methanol could be achieved under the conditions of a water-to-methanol ratio of 1.2 and a reaction temperature of 493 K, and the H2 time-space yield could reach 103.9 mol kg−1 h−1. Furthermore, even after 10 h of thermal treatment test at 723 K, the CZAT-EA catalyst maintained a high methanol conversion rate. [ABSTRACT FROM AUTHOR]

CeO2@TiO2 core–shell nanostructures are synthesized at various titania contents by the sol–gel method. Such supports have been evaluated in the CO oxidation reaction to study lattice oxygen mobility. Also, FexOy/CeO2@TiO2 synthesized by the impregnation method to study the catalytic activities of the degradation of methylene blue and carmoisine dyes in Fenton-like processes. CeO2@TiO2 catalysts with a higher proportion of rutile have better activity in CO oxidation. The oxidation of dyes proceeds most efficiently on Fe-composites with titania containing a higher proportion of metastable phases of titania (anatase + brookite), in contrast to CO oxidation catalysts. The catalytic behavior of the materials was discussed to determine the role of the core–shell structure, ceria–titania interaction, and other particular qualities. The proposed systems can be promising catalysts for environmental protection. [ABSTRACT FROM AUTHOR]