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Fe, N co-doped carbon electrocatalyst is one of the most attractive alternatives to Pt/C catalysts due to its high catalytic activity, excellent stability and low cost. However, obtaining stable and efficient Fe, N co-doped carbon oxygen reduction reaction (ORR) catalysts based on simple processes is still a challenge. Herein, Fe, N co-doped porous carbon (Fe–N–C) with an open macroporous frame structure is prepared by using inorganic molten salts (FeCl3·6H2O and ZnCl2) and ethylenediaminetetraacetic acid as the template and nitrogen-containing carbon precursor, respectively. The open pore structure of the Fe–N–C material precisely tailored with the inorganic molten salt template exhibits high specific surface area (676.5 m2 g−1) and appropriate pore size, which can promote oxygen adsorption and expand the oxygen reduction interface, resulting in the acceleration of the electron/charge transfer processes and an improved electrocatalytic performance. The optimized Fe3–N–C-800 electrocatalyst exhibits good catalytic activity for ORR, such as high onset potential of 0.998 V and half wave potential of 0.84 V in alkaline media, as well as high stability and methanol tolerance. Furthermore, a novel Zn–air battery assembled with carbon paper containing Fe3–N–C-800 electrocatalyst as air cathode shows high open-circuit voltage (1.485 V), high specific capacity (870 mA h g−1 at 10 mA cm−2), excellent reversibility and stability. The proposed synthetic strategy provides new opportunities to design and construct carbon frame materials with the desired open macroporous structure to improve their electrocatalytic performance. [ABSTRACT FROM AUTHOR]

4-Aminophenol (4-AP) is a highly toxic environmental pollutant and contaminant of medicine, which is widely used in industries and daily life. Therefore, the development of a reliable sensor for determining the amount of 4-AP is of great importance for the protection of human and environmental health. Herein, by fabricating a Pd@CeO2 composite on a nanoporous gold-coated carbon fiber paper (NPG/CFP), the sensing properties for 4-AP can be largely enhanced. Combining the significant increase in the catalytic activity of the Pd@CeO2 composite (derived from the strong interactions between Pd and CeO2) with the NPG and NPG/CFP hierarchical porous structure having a high electrochemically active surface area, the electrode achieved excellent detection of 4-AP. It manifested an extremely high sensitivity of 75.4 μA μM−1 and 56.5 μA μM−1 in the concentration range from 0.005 μM to 0.03 μM and 0.03 μM to 9 μM, respectively. The detection limit reached as low as 4 nM under optimized conditions (S/N = 3). The electrode also possesses long-term stability and presents great anti-interference ability. All these results demonstrate that the electrode is a promising candidate for future sensors for monitoring 4-AP in water and pharmaceuticals. [ABSTRACT FROM AUTHOR]

p53 gene is one of the most important anticancer genes and has been recognized as a typical biomarker for the early diagnosis of cancers. In this paper, a portable point-of-care testing (POCT) platform was developed for the colorimetric and photothermal dual-modal analysis of the p53 gene. Long concatemer G4 structures with high catalytic activity were formed by a target-driven hybridization chain reaction, and their catalytic properties can further be enhanced with the help of iodide ions. This dual-modal method realized the sensitive multicolor visual point-of-care detection of the p53 gene, where color variations from colourless to blue were easily distinguished by the naked eye. The temperature output was achieved by effective photothermal conversion and regulation guided by the accumulated concatemer G4 complexes in the TMB–H2O2 system, avoiding the need for complex instruments. The proposed dual-modal assay for p53 gene detection is cost-effective, simple, highly sensitive (3.34 pM), stable, and remarkably selective. It was also applied to determine the concentration of the p53 gene in spiked serum samples. [ABSTRACT FROM AUTHOR]

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]

Sensitive detection of glucose is important for public health, but non-enzymatic glucose biosensors still face significant challenges. In this paper, a novel and sensitive non-enzymatic glucose sensor was developed by in situ preparation of CuO nanorod-supported NiCo LDH nanosheet arrays on copper foam (CuO@NiCo LDH NSAs/CF). Because the hierarchical core–shell nanostructure provides more active sites and increases the exposed surface area of the catalyst, the catalytic activity of the electrode was significantly increased. As a working electrode, the CuO@NiCo LDH NSAs/CF catalyst showed good glucose sensing performance in a linear range of 0.6 μM–3 mM and a detection limit of 0.16 μM (S/N = 3). The sensor also showed repeatable responses over a month with negligible interference, and satisfactory recoveries with real human serum samples. [ABSTRACT FROM AUTHOR]

In this paper, ultrathin layers of carbon nitride were obtained by dissolving urea in different amounts of water and used as a carrier to prepare catalysts for formic acid dehydrogenation. The catalytic activity of the carbon nitride supported Pd catalyst in formic acid dehydrogenation was investigated. The ratio of urea to water played a key role in the type and content of nitrogen-containing functional groups, and then enhanced the catalytic performance by regulating the electronic properties of Pd. The Pd/CN-U1W5 catalyst exhibited excellent catalytic activity for the production of hydrogen from formic acid with an initial TOF of 1058 h−1 at 348 K. It was found that the high catalytic performance of the catalyst could be attributed to the strong interaction between Pd nanoparticles and pyridinic N, small Pd nanoparticle size and highly dispersed Pd nanoparticles. [ABSTRACT FROM AUTHOR]

In this paper, a 3D porous polycalix functionalized with a dual Brønsted–Lewis acidic double-charged DABCO-based ionic liquid group (PC4RA@[SiPrDABCO@BuSO3H](FeCl4)) was synthesized using multiple steps, characterized, and then evaluated by spiro formation for catalytic activity. Initially, the polymeric support was modified using the silylation of its hydroxy groups with (3-chloropropyl)-trimethoxysilane as an organo-silane linker to develop PC4RA-SiPrCl. Then, it was post-functionalized using bi-functional acidic IL groups bearing double-charged diazoniabi-cyclo[2.2.2]octane tetrachloro-ferrate(III) with moving active sites of SO3H groups to deliver PC4RA@[SiPrDABCO@BuSO3H](FeCl4). In the next step, the characterization of the designed catalyst was directed by applying FT-IR, EDX, elemental mapping, WPXRD, LPXRD, FE-SEM, STA, and TEM techniques. The catalytic performance of the porous polymeric system was confirmed using the formation of spiro-fused[4H-pyran] as a highly recyclable and stable di-cationic polymer-supported acidic IL under mild conditions. [ABSTRACT FROM AUTHOR]

The development of noble-metal-free electrocatalysts with high catalytic efficiency, low cost, and high durability in pH-universal media is encountering a bottleneck in practical applications. In this paper, Ni@MoN-700 coral hybrids were prepared using hydrogen evolution reaction (HER) catalysts, which were synthesized by a high-temperature reduction of NiMoO4 nanorods with urea. It was found that the annealing temperature seriously affects the surface morphology and chemical composition of the catalysts. Besides, structural reorganization occurred during the HER, which involved the joining of pyrrolic N, metal nitrogen, Mo3+, and Mo6+, governing the HER performance. Also, during the HER, Ni and Mo could synergistically improve the overall catalytic activity of the catalysts, via electronic interactions. These advantages endow Ni@MoN-700 with exceptional endurance and great HER activity, with a low overpotential of 30 mV and 76 mV at 10 mA cm−2 in alkaline and acidic media. These characteristics are similar to those of Pt under alkaline conditions. NiMoN catalysts show unusual activity and long-term stability, indicating a wide range of potential applications. [ABSTRACT FROM AUTHOR]

This paper reports the synthesis of a nickel-silver-graphene quantum dot-graphene hybrid. Histidine-functionalized graphene quantum dots (His-GQDs) were bonded to graphene oxide (GO) and then combined with Ni2+ and Ag+ to form a NiAg/His-GQD/GO complex, followed by thermal reduction under N2. The resulting hybrid offers a well-defined three-dimensional structure. The NiAg nanoparticles are uniformly dispersed on the graphene sheets. The special architecture creates high oxidase-like catalytic activity towards the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) into a blue product. Furthermore, the hybrid was used as a mimetic enzyme for colorimetric detection of malathion. In the detection, acetylcholinesterase catalyzes hydrolysis of acetylthiocholine to produce thiocholine. In the presence of malathion, the catalytic activity of acetylcholinesterase was effectively inhibited. This will lead to a reduced thiocholine concentration. As sulfhydryl in the thiocholine can combine with silver and nickel in NiAg/His-GQD/G to form Ag–S and Ni–S bonds, the presence of thiocholine results in a reduced oxidase-like catalytic activity of NiAg/His-GQD/G. With the increase of malathion, NiAg/His-GQD/G gives a higher oxidase-like catalytic activity. This causes a faster rate for oxidation of TMB, indicating an increased absorbance of the blue product. The result shows that the inhibition rate has a good linear relationship with the malathion concentration in the range of 10–120 ng mL−1 and detection limit of 3.10 ng mL−1 (S/N = 3). Meanwhile, the sensing platform was also applied to paper strips for rapid determination of malathion in vegetable samples by using a smartphone application (APP), which provides a promising platform for on-site pesticide detection. [ABSTRACT FROM AUTHOR]

Chemical vapor deposition (CVD) and impregnation (IM) methods were applied in the preparation of novel Fe/LTA (Linde Type A) zeolite membrane/paper-like sintered stainless steel fiber (Fe/LTA/PSSF) catalysts for acetone oxidation. The catalysts were characterized using various techniques, such as actual iron loading (AAS), surface morphology (SEM), phase composition and crystallite size (XRD), specific surface area (BET), valence state (XPS) and reducibility (H2-TPR), to investigate the effects of the calcination process, iron loading, preparation methods and supports on their catalytic activity. The calcined catalysts were more active than the non-calcined catalysts in the catalytic oxidation of acetone due to the different oxidation states of the deposited metal species. The catalysts prepared by CVD with an Fe loading of 2.29% exhibited similar activity to the IM-prepared catalysts with Fe loadings of 4.42% and 9.69%, which may be attributed to the superior dispersion of the active Fe2O3 phases, the smaller size of metal oxide and the increased ability for oxygen storage. Among the IM-prepared catalysts, Fe/LTA/PSSF-IM-2 with an Fe loading of 4.42% exhibited the lowest T90 of 230 °C. Additionally, the catalysts coated on LTA/PSSF showed higher activity and contact efficiency (T90 of 249 °C) compared to those on granular zeolite (T90 of 318 °C). [ABSTRACT FROM AUTHOR]

Liquid phase oxidation of 2-methylnaphthalene (2-MN) is a common synthetic route for the preparation of 2-methyl-1,4-naphthoquinone (2-MNQ). Metal-free carbon materials doped with heteroatoms have been proven to have excellent catalytic potential in various reaction fields. In this paper, the catalytic performance of N, F co-doped benzoxazine carbon materials for the selective oxidation of 2-MN was studied. The results show that the catalyst obtained at a carbonization temperature of 700 °C has the best catalytic performance. Under optimized conditions, the 2-MN conversion is 97.9%, and the 2-methyl-1,4-naphthoquinone selectivity is 84.3%. In addition, this catalyst still exhibits good catalytic activity after five cycles. Based on the experimental and characterization results, graphitic nitrogen species play a key role in the catalytic reaction and there is an almost linear relationship between the F content and the selectivity of 2-MNQ. This work provides a greener and more efficient method for the preparation of 2-MNQ with N/F co-doped mesoporous carbon. [ABSTRACT FROM AUTHOR]

To solve the problem of excessive energy consumption in the process of catalytic water splitting, it is quite essential to exploit high-activity and low-cost electro-catalysts. The present paper proposes a highly catalytically active Ni/Fe hydroxide electro-catalyst for the oxygen evolution reaction (OER), which is in situ formed on the surface of the stainless steel fiber felt using a sacrificial template by adding the oxidizing agent K2S2O8 to the alkaline solution under mild conditions. The electrode prepared using this simple one-step chemical oxidation method obviously shows enhanced catalytic activity for the OER. The overpotentials at 10 mA cm−2 are only 214 mV and 263 mV in KOH and Na2CO3/NaHCO3 solutions, respectively. In addition, the potential and morphology of the electrode remain stable for 180 h at 10 and 100 mA cm−2 in the Na2CO3/NaHCO3 system, demonstrating its ultra-high stability. This new route to prepare OER electrode materials has a promising bright application prospect for large-scale production. [ABSTRACT FROM AUTHOR]

Glucose oxidase has great potential as a bio-catalyst for the determination of glucose and H2O2 concentration, but it is sensitive to environmental influences and has poor recoverability. To overcome this limitation, this study presents a promising approach, i.e., glucose oxidase interposed with dopamine and ZIF-8 to develop a highly efficient and stable bio-catalyst for H2O2 production while determining glucose concentrations. The successful synthesis of GOx@ZIF-8/PDA was verified by SEM, EDS, XRD, FTIR, XPS, and UV analyses; GOx@ZIF-8/PDA exhibited higher stability, better reproducibility, and excellent glucose assay potential compared with the free enzyme. After 7 days of storage, GOx@ZIF-8/PDA almost maintained its initial activity, and the catalytic activity remained at 92.15 ± 2.13% after five consecutive applications. This study provides a new strategy for the preparation of highly active and stable immobilized enzymes. [ABSTRACT FROM AUTHOR]

In this study, red mud (RM), an industrial waste, was used as a raw material to prepare a novel red mud-based Co3O4–Fe2O3–Co2AlO4 (Co–Fe/RM) catalyst using a simple solid-phase method, and lomefloxacin hydrochloride (LOMH) was degraded by using Co–Fe/RM to activate peroxymonosulfate (PMS). The optimum preparation conditions of the mass ratio of Co(NO3)2·6H2O to RM, calcination temperature and calcination time were 1.5 : 1 (1.5 g of Co(NO3)2·6H2O and 1 g of RM), 700 °C, and 2 h, respectively. The characterization results showed that Fe2O3, Co3O4 and Co2AlO4 were the main active components in Co–Fe/RM, and Co–Fe/RM could expose more reaction sites compared with RM. The Co–O–Al bonds that existed on the Co–Fe/RM could facilitate the redox cycle between Co(II) and Co(III), thus improving the Co–Fe/RM catalytic activity. For 10 mg L−1 LOMH solution with a volume of 100 mL, the maximal removal ratio of LOMH (89.3%) was obtained at 20 min under the optimal parameters (0.3 g L−1 Co–Fe/RM dosage, 1 mmol L−1 PMS concentration, initial pH 5.5, and 30 °C of reaction temperature) in a Co–Fe/RM/PMS system. The trapping experiments proved that SO4˙−, 1O2 and O2˙− dominated the degradation of LOMH, and a possible catalytic mechanism of activating PMS using the prepared catalysts was proposed. For LOMH in the Co–Fe/RM/PMS system, degradation pathways were analyzed via density functional theory (DFT) calculations and liquid chromatography–mass spectrometry (LC–MS). A toxicity estimation software tool (TEST) and the Chlorella pyrenoidosa cultivation experiment were used to evaluate the biological toxicity of the treated LOMH solution. The recycling experiments found that the Co–Fe/RM had distinguished reusability and excellent stability. The mineralization assessment showed that organic carbon contents could be effectively diminished in the treated LOMH solution. This study provided a viable way for the beneficial use of RM to activate PMS and offered a low-cost and efficient catalyst for the degradation of pollutants in wastewater. [ABSTRACT FROM AUTHOR]

The synthesis of noble metal/TiO2 composites without the use of additional reducing agents or surfactants is a notable achievement in catalyst preparation, as it simplifies the process and reduces potential impurities. A detailed analysis of catalysts using a range of methods like XRD, TEM, XPS, BET, and FT-IR offers a comprehensive insight into their structural and surface characteristics, essential for understanding their catalytic performance. The observation of enhanced catalytic activity with Pt-loaded composite catalysts compared to Pd and Au-loaded counterparts highlights the importance of noble metal selection in catalytic applications. Through BET and TEM characterization, it can be observed that there is no significant difference between the specific surface area of all noble metal/TiO2 composites and the size of the noble metal, which ranges from 2–7 nm. The correlation between the catalytic efficiency and the metal work function, along with the insights from XPS analysis, underscores the significance of the metal–titanium dioxide interaction in determining catalytic efficiency. This interaction may involve tuning the surface's electronic structure, the chemical bonding between the metal and the carrier, and the formation of surface active sites. These sites can adsorb reactants and facilitate the reaction, thus improving the catalytic activity and selectivity. This study provides an in-depth understanding and an important reference for the design and optimization of catalysts for hydrogen production from formic acid, which can help promote progress and applications in related fields. [ABSTRACT FROM AUTHOR]

[V(N-2,6-Cl2C6H3)(CHSiMe3)(OC6X5)(NHC)] [X = F (1), Cl (2), NHC = 1,3-bis-(2,6-dimethylphenyl)-imidazol-2-ylidene], exhibited remarkable catalytic activities [TOF = 133–193 s−1 (1), 90.9–126 s−1 (2)] for ring opening metathesis polymerisation (ROMP) of norbornene (NBE) at 25 °C to afford ring-opened polymers not only with high cis-(93–98%) selectivity, but also with exclusive syndiotactic stereo-regularity. These polymerisations proceeded in a living manner under optimised conditions. The activity improved at 50 °C with decreasing in the cis specificity. Synthesis and the structural analysis of the fluorinated alkoxide complexes, [V(N-2,6-X2C6H3)(CHSiMe3){OC(CF3)3}(NHC)] [X = F (3), Cl (4)] have been studied, and the difluorophenylimdo complex (3) exhibited comparable catalytic activities for ROMP of NBE. The cis selectivities in the resultant polymers prepared by 3 were low (88%) and the selectivities in the ring-opened poly(tetracyclododecene) (TCD) were low (61–66%) compared to those in poly(NBE)s. The resultant ring opened poly(TCD) possessed syndiotactic stereo-regularity confirmed by DSC thermogram of the hydrogenated polymers. [ABSTRACT FROM AUTHOR]

Oxidative dehydrogenation (ODH) of propane is a promising alternative route for propene production. In this work, we developed a series of vanadium and gallium oxides supported on γ-Al2O3 catalysts by an incipient wetness impregnation method. Among the employed catalysts, the VGA-2 showed superior catalytic activity, and the catalyst was demonstrated for longevity in ODH of propane with a stable activity using a continuous flow fixed bed reactor at 400 °C. H2-TPR and UV-visible spectra showed the presence of highly dispersed monomeric VOx species with tetrahedral coordination geometry, which influences product selectivity. The characterization results also conferred that the redox nature of vanadium (V5+ and V4+) oxide and higher V5+ content on the surface of the VGA-2 catalysts are more favourable for C–H activation. In addition, the pyridine-FTIR and 71Ga solid-state NMR studies further substantiated the presence of Lewis acid sites and tetrahedrally coordinated Ga3+Ox species that are highly responsible for the ODHP activity, respectively. Furthermore, in situ-DRIFTS studies conferred that the propane adsorption at ambient temperature showed the formation of intermediate propoxide species with the evolution of σ-bonds and with further increase in the temperature to 325 °C; the stretching vibrations of the ＝C–H and –C–H bonds in the propylene molecule were observed. The spent catalysts were also analyzed by thermogravimetric analysis, where the optimized catalyst (VGA-2) showed the least coke deposition. [ABSTRACT FROM AUTHOR]

Direct synthesis of dimethyl carbonate (DMC) from CO2 and CH3OH holds significant economic and environmental value. Numerous catalysts have been employed for this reaction, yet further enhancement of its activity requires a deeper understanding of the catalyst's structure–activity relationship and catalytic mechanism. In this study, we utilized structurally well-defined and highly tunable MOF-808 as a research platform. Functionalizing MOF-808 with ethylenediamine (MOF-808-ED) boosted the space time yield of DMC from 3.25 mmol g−1 h−1 to 7.23 mmol g−1 h−1. The experimental results demonstrate that the reaction involves acid–base synergistic catalysis, where an appropriate balance of acid–base site content is crucial for CO2 and CH3OH to produce DMC, as it facilitates the formation of the key intermediates (CH3OCOO*). Additionally, the nucleophilicity of N is stronger than that of O, further promoting the catalyst's enrichment and activation of CO2. Finally, employing in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) testing, we elucidated the mechanism by which the MOF-808-ED catalyst, with –NH2 as base sites and Zr as acid sites, facilitates the synergistic catalysis of the reaction. This study provides insights into the synergistic effects of acid–base sites on the synthesis of DMC from CO2 and methanol, offering valuable guidance for the development of high-performance catalysts. [ABSTRACT FROM AUTHOR]

The catalytic efficiency of CeO2 in soot oxidation was significantly affected by its grain morphology and calcination temperature. Nanocube-shaped and nanorod-shaped CeO2 catalysts were synthesized via a hydrothermal method with different calcination temperatures. Activity tests revealed that the nanorod-shaped CeO2 exhibited superior catalytic activity compared to the nanocube-shaped catalysts at equivalent calcination temperatures. Furthermore, an inverse relationship between the catalytic activity and the calcination temperature was observed in the nanorod-shaped CeO2 catalysts, with those calcined at 300 °C exhibiting the most effective low-temperature catalytic performance. Combined characterization techniques and density functional theory calculations showed that the improved catalytic performance can be attributed to the increased abundance of oxygen vacancies, enhanced lattice oxygen mobility and higher surface energy due to their unique surface defect structure and electronic structural feature, in addition to the reduction in grain size. [ABSTRACT FROM AUTHOR]

In this study, NiTiO3 nanoparticles supported on exfoliated montmorillonite K30 (MK30) were synthesised in an eco-friendly manner using ultrasonication and were used as a benign heterogeneous catalyst for the synthesis of 4-amino pyrimidine analogues in a microwave medium. The nature of the catalyst was investigated using various characterization techniques, including XRD, FT-IR, TGA, BET, FE-SEM, TEM, and XPS. The catalytic activity of the synthesised catalyst was examined, and 20% NiTiO3/MK30 at 25 wt% showed efficient catalytic activity with high yields compared to other loadings. Non-conventional microwave irradiation was used to carry out the reaction under mild conditions, resulting in a high conversion rate. The reaction was optimised with respect to the type and amount of the catalyst, temperature, solvent, and microwave power. The scope of the reaction was extended using various aldehyde derivatives, which also produced high yields. After 6 cycles, the recovered catalyst showed good catalytic activity, achieving high yields (88–95%) within 5 min. Mechanistic investigation of the reaction hypothesized the 1st step as the synthesis of arylidene malononitrile via Knoevenagel condensation of aldehyde and di-cyanomethane, followed by the Michael addition of acetamidine to arylidene malononitrile and aromatisation to produce 2-methyl-4-amino-pyrimidine-5-carbonitriles. This synthetic approach offers several advantages, including high yield, benign reaction conditions, short reaction time, straightforward work procedure, and catalyst reusability. [ABSTRACT FROM AUTHOR]

In advanced oxidation processes (AOPs), the degradation of organic pollutants by the oxidation of reactive oxygen species (ROS) generated from the interaction between H2O2 and active species Fe2+/Fe3+ has gained significant attention. The cycle of Fe2+/Fe3+ in the catalytic oxidation plays a key role. Herein, a kind of N-doped carbon encapsulated FeMoxOy nanocrystalline material (FeMo@NC) was fabricated using a precipitation–calcination approach and applied to degrade organic pollutants in AOPs. The composite catalyst presents efficient catalytic activity for removing rhodamine B (RhB), methylene blue (MB), congo red (CR) and methyl orange (MO). The facilitating effect of Mo on the Fe2+/Fe3+ cycle and the phase structure and composition of the catalyst on the degradation was explored. Meanwhile, the recovery and reusability of the catalyst were assessed, proving its excellent stability in the degradation process. Quenching experiments demonstrate that the catalyst can activate H2O2 to generate singlet oxygen (1O2) that serves as the main ROS to degrade RhB, and the degradation pathway and mechanism are then proposed. [ABSTRACT FROM AUTHOR]

4-Nitrophenol (4-NP) is an important industrial intermediate that poses serious ecological risks and affects human health if exposed directly to the environment without treatment. 4-NP is less toxic when reduced to 4-aminophenol (4-AP) and can be used in a wide range of applications. In this study, copper-loaded chitin/hydroxyapatite composite hydrogels (Ch/HA-Cu) were prepared by in situ reduction of Cu2+. The catalytic reduction performance of Ch/HA-Cu catalysts for 4-NP was investigated. 10 mg of Ch/HA-Cu catalysts reduced 4-NP (0.1 mM) in 4 min. The increase in the starting concentration of 4-NP significantly improved the reduction of 4-NP, but also prolonged the reaction time. The activation energy required for the reduction of 4-NP by Ch/HA-Cu was about 40.68 kJ mol−1 and the reaction rate constant k was 0.61 min−1. The interfering substances affected the replacement efficiency of the reactants on the surface of Ch/HA-Cu and slowed down the reaction. The catalytic efficiency of Ch/HA-Cu for the reduction of 4-NP still reached more than 97% after five cycles of experiments, showing excellent catalytic activity and reaction stability for 4-NP, indicating that the prepared Ch/HA-Cu can be used as an economical and reusable multiphase reactor for the abatement of organic pollutants. [ABSTRACT FROM AUTHOR]

The solvothermal method of producing spherically shaped and highly fluorescent tiny (∼3 nm) nitrogen-doped carbon quantum dots (NCQDs) with high quantum yield (43%) from Ixora coccinea flowers and o-phenylenediamine has been approached sustainably. Since these NCQDs exhibit excitation-dependent fluorescence activity, they were used to detect the Fe3+ ion selectively in real-time in human blood serum, because it is a component of human blood. The limit of detection (LOD) of the NCQDs was found to be 60 nM. We also synthesized palladium nanoparticles utilizing the NCQDs without additional reducing or stabilizing agents because these quantum dots serve as both. Numerous characterization techniques were used to characterize the nanoparticles, and all the characterizations showed the presence of NCQDs, which stabilize the nanoparticles. Palladium nanoparticles' small size (4 nm) and large surface area (35.77 m2 g−1) enable them to exhibit strong catalytic activity in Suzuki–Miyaura coupling and cyanation processes. It is obvious that synthetic palladium nanoparticles and NCQDs have a variety of uses in the fields of catalysis and sensing respectively. [ABSTRACT FROM AUTHOR]

Co–Mo sulfides with tube-like structures were prepared through a low-temperature pre-sulfurization process using rod-like CoMoO4 as the precursor. Pre-sulfurization solvents with different polarities markedly affected the textural properties, the concentration and microstructure of the active components, and the catalytic deoxygenation activity. The increased solvent polarity can promote the formation of hollow structures and the degree of sulfurization of the precursor, and the appropriate polarity of pre-sulfurization solvents is helpful for the sulfurization of CoMoO4 to form (Co)MoS2 slabs with shorter lengths and greater stacking numbers, which means more coordinatively unsaturated sites, especially corner sites. The results of the hydrodeoxygenation reaction of stearic acid suggested that a higher fc/fe resulted in a greater reaction rate of stearic acid, and the yields of the liquid products were highly dependent on the number of surface-active sites, which mainly originated from type II CoMoS species. Moreover, increasing the reaction temperature favored the direct hydrodeoxygenation pathway. [ABSTRACT FROM AUTHOR]

In this work, commercial chitosan was used as a recyclable and biodegradable catalyst for efficient one-pot synthesis of coumarin-3-carboxylic acids in water or ethanol:water (3 : 7, v/v) at 75 °C via Knoevenagel-intramolecular cyclization cascade reaction. Coumarin-3-carboxylic acids (3a–i) were obtained from different substituted salicylaldehydes and Meldrum's acid under mild conditions in short times (10–45 min) and good isolated yields (77–88%) without requiring laborious purifications. The proposed method combined the advantages of homogeneous catalysis with recovery and recyclability of four times catalyst without compromising its catalytic activity and structural integrity. In the evaluation of in vitro antimicrobial activity against 4 bacterial and 8 fungal strains, the tested coumarin-3-carboxylic acids 3c–e, 3h, and 3i showed an inhibitory effect on the growth of the microorganisms (1024–256 μg mL−1). Product 3d showed the lowest MIC against fungal and bacterial strains (256 μg mL−1), suggesting a bactericidal and fungicidal nature. [ABSTRACT FROM AUTHOR]

A series of Cd(II) complexes, [(PPh3)2Cd(SCOf)2] (1), [PPh4]2[Cd(SCOf)2(μ-Br)]2 (2), [(PPh3)2Ag(μ2-SCOf)2Cd(SCOf)] (3), Na2[(PPh3)Cd(MeOH)(SCOf)3]2 (4a) and Na2[(PPh3)Cd(SCOf)3]2.C7H8 (4b) (Where SCOf = furan-2-thiocarboxylate), have been synthesized and characterized by single crystal X-ray analysis and other spectroscopic techniques. Complexes 1 and 2 show distorted tetrahedral and distorted trigonal bipyramidal geometries around Cd(II), respectively. In the case of 3, Cd(II) exhibits a trigonal prismatic structure, whereas, Ag(I) is at the center of a distorted tetrahedron. Complex 4, has a trigonal pyramidal geometry, hitherto unknown for a Cd(II) center. The catalytic activities of complexes for the synthesis of dihydropyrimidinone have been investigated. Out of four complexes, complex 4 is the most efficient catalyst for the one-pot multicomponent Biginelli-type coupling toward the synthesis of dihydropyrimidinone. Excellent yields of the desired products were obtained with very low catalyst loadings (1 mol%). With a few examples, the versatility and scope of the method have also been demonstrated. The catalysts were also tested for their recyclability. [ABSTRACT FROM AUTHOR]

A novel pyrazole-based catalyst system featuring –CH as a hydrogen bonding donor was developed and utilized for the conversion of CO2 into cyclic carbonates without the use of metals or co-catalysts. It is intriguing that the synthesized pyrazolium ionic liquid ([Bn2DMPz]Br) could efficiently catalyze the coupling reaction of carbon dioxide (CO2) and epoxides at 90 °C, under a pressure of 0.1 MPa CO2, achieving a product yield of up to 99% within just 5 hours. The catalyst can be recycled and reused multiple times without any decrease in its catalytic efficiency. In addition, the pyrazolium ionic liquid was polymerized to get the first pyrazole-based poly(ionic liquid) (PIL). The polymer also exhibits high catalytic activity, excellent stability and easy recyclability. In comparison to other catalysts based on ionic liquids, our catalyst system demonstrates outstanding performance and recyclability at the same time. DFT calculations show that "double-IL" model may easily make the bromide anion serve as a nucleophile and cation [Bn2DMPz]+ serves as a H-donor to stabilize the O− of the epoxide and the carbonate anion with weak interaction. The design strategy based on pyrazole ionic liquid will inspire researchers to develop more catalysts used for CO2 cycloaddition in the future. [ABSTRACT FROM AUTHOR]

We report an efficient synthetic route for the synthesis of tetrahydro indole-2,4-diones from readily available β-enaminones and glyoxal and subsequent I2/DMSO-mediated oxidation/aromatization of tetrahydro indole-2,4-dione to produce 4-hydroxyisatin derivatives. The key aspect of this protocol includes the dual catalytic activity of molecular iodine in the presence of DMSO. Mechanistic study suggested that this reaction is substrate selective as corresponding aromatization and sp3 C–H oxidation stops in the presence of 6,6-disubstituted tetrahydro indole-2,4-dione. Additionally, a thorough investigation into the synthesis of tetrahydro indole-2,4-dione follows acid-catalyzed cyclization/dehydration/enol–keto tautomerism from β-enaminones and glyoxal. [ABSTRACT FROM AUTHOR]

Selective oxidation of benzyl alcohol to benzaldehyde is one of the vital reactions because of the commercial application of benzaldehyde in various chemical and pharmaceutical industries. This work investigates a gentler method for creating NiFe2O4 nanoparticles (NPs) by a co-precipitation method combined with hydrothermal ageing in the presence of poly(ethylene glycol) (PEG) of different molecular weights. The investigation findings reveal the formation of well-crystalline cube-shaped and a mixture of spherical and cube-shaped particles depending on the concentration of the additive. The formed particles are magnetically ordered exhibiting superparamagnetic behaviour at room temperature with saturation magnetization (Ms) values ranging from 41.0 to 43.0 emu g−1. The as-prepared NiFe2O4 NPs can selectively catalyze the oxidation of benzyl alcohol to benzaldehyde at room temperature under sonochemical conditions in the presence of tert-butyl hydroperoxide. Under the optimized conditions, 90% of benzaldehyde with 100% selectivity in 2.0 h at room temperature (25–30 °C) is recorded. The versatility of the current protocol has been extended to a variety of substituted benzyl alcohols with good to excellent performance under the optimized reaction conditions. The NiFe2O4 NPs are magnetically separable and can be reused for up to seven cycles without losing their catalytic activity. [ABSTRACT FROM AUTHOR]

Selective oxidation of toluene into high-value-added benzaldehyde is meaningful and challenging. In this study, a series of amorphous SiO2-supported bimetallic Cu–V oxides were prepared, showing excellent catalytic activity for the oxidation of toluene compared to their mono-metallic oxide catalysts. It was found that the best catalytic performance was observed with benzaldehyde selectivity of 87.3% and toluene conversion of 84.1% under mild reaction conditions, using peroxydisulfate (PDS) as the oxidant. The main by-product was benzoic acid. A strong synergistic interaction between Cu and V species has been revealed via a series of characterization techniques, which can boost the catalytic performance. This work may provide a green and cheap process for the selective oxidation of toluene to benzaldehyde. [ABSTRACT FROM AUTHOR]

Nanozymes show great potential in organic degradation because of their good stability and low cost. However, their poor catalytic activity and functional diversity restrict their practical applications. The present study reports the synthesis of a Pt/Co/Co3O4/EW-GQD nanozyme via the coordination of Co2+ and Pt4+ with a glutamate and tryptophan-functionalized graphene quantum dot (EW-GQD) and subsequent thermal reduction and part oxidation. The graphene surface ligand engineering creates a reactive microenvironment similar to natural enzymes, facilitating a high-speed electron-transfer process from Co3O4 to graphene and strong adsorption capacity toward rhodamine B. The Co and Pt double doping narrows the bandgap and leads to an improved electronic conductivity. The Pt/Co/Co3O4/EW-GQD nanozyme exhibited a peroxidase-like specific activity of 1662.67 U mg−1 and oxidase-like specific activity of 293.45 U mg−1, which exceed by 3.2-fold that of horseradish peroxidase and by 15.6-fold that of choline oxidase. This enabled a 3.6-fold increase in the degradation efficiency of rhodamine B without the need for an activator. The high catalytic activity was mainly attributed to the perfect combination of the graphene surface ligand and Co and Pt double engineering, which produced multiple active sites such as Co3+/Co2+, Pt4+/Pt2+, and pyrrolic N/pyridinic N and multiple active species such as 1O2, ˙O2−, and ˙OH. This work introduces a novel way for the design and synthesis of nanozymes with excellent catalytic activity and multifunctional performance. [ABSTRACT FROM AUTHOR]

FeCo2O4 is a potential OER catalyst, but its catalytic activity still needs to be further improved due to its poor electrical conductivity and low material utilization. In this paper, we construct oxygen-vacancy-rich two dimensional FeCo2O4 nanosheet materials using a liquid-phase reduction strategy. Benefiting from its large specific surface area, numerous surface catalytic sites, enhanced electrical conductivity, and modulated electronic structure, the catalyst exhibits an overpotential of only 270 mV at a current density of 10 mA cm−2, which is lower than that of the original FeCo2O4 nanosheets (420 mV). At the same time, the catalyst can run steadily for 20 hours without obvious decay. [ABSTRACT FROM AUTHOR]

Among rare earth oxides (REO), mixed-valence praseodymium oxide (Pr3+/Pr4+) has the highest O mobility and very promising applications in multiphase catalysis. In this paper, Pd-loaded praseodymium oxide nanotubes were successfully prepared by immobilizing Pd nanoparticles on modified carriers. XPS characterization showed that the electron transfer process during the reaction could be regulated by changing the Pr3+/Pr4+ ratio of praseodymium oxide. Importantly, the H2-PrxOy carrier surface has much higher Pd electron density, and the electron-rich Pd nanoparticles make it easier to break the C–Br bond and transfer electrons from Pd to C and Br atoms, leading to the formation of ArPdIIBr intermediate complexes. In the Suzuki coupling reaction, Pd/H2-PrxOy exhibited higher catalytic performance under mild conditions. There is a strong correlation between the surface properties of the carriers and the catalytic activity of the Pd nanocatalysts. This provides a new strategy for the preparation of Suzuki coupling reaction catalysts. [ABSTRACT FROM AUTHOR]

Exploring active catalyst components is very important to develop high-performance and highly stable ORR electrocatalysts to replace costly Pt-based catalysts, though it remains an ongoing challenge. In this paper, three ORR catalysts with different active components were obtained by calcination of different proportions of mixed precursors simply and delicately. Among them, precursor 1 (bimetallic polymer Fe/Zn-ZIFs@ZnCO3) played the role of a self-sacrificing template, while precursor 2 (an N, P-co-doped polymer) played the role of a volatile atmosphere. Precursor 2 also embedded N and P heteroatoms into the carbon framework during high-temperature volatilization, which resulted in subtle changes in the active catalyst components. Finally, a hybrid of metal Fe and α-Fe2O3 nanoparticles embedded in N, P-codoped carbon nanotubes with many separated gullies (named α-Fe2O3/Fe@NPC) exhibited excellent ORR catalytic activity in an alkaline solution as compared to commercial Pt/C. This work provides a new strategy for designing controllable active components using volatile precursors. [ABSTRACT FROM AUTHOR]

This paper mainly studied the influence of the Si/Al ratio on the performance of the Cu/SSZ-13 catalyst synthesized by the ion exchange method. NH3-SCR experimental results show that the catalyst SAR10 has the best catalytic performance, and it can maintain a 100% conversion rate in the range of 250 °C to 600 °C. Although SAR6 samples with low Si/Al ratios have abundant active centers, their low temperature activity is poor due to their poor crystallinity. The decrease of the number of active sites available for exchange in the SAR25 sample with too high an Si/Al ratio results in a decrease in catalytic activity throughout the temperature range. The results of the in situ DRIFTS experiment show that the order of the number of Lewis acid sites and the content of monodentate nitrate adsorption sites is the same as the order of catalytic activity. [ABSTRACT FROM AUTHOR]

Developing low-cost high-efficient electrocatalysts for alkaline hydrogen evolution reaction (HER) is of critical significance in hydrogen production via alkaline electrolyzers. Herein, we prepared CeO2/Co4N heterostructure for the catalyst in alkaline HER, which introduced a synergistic effect within the CeO2 and Co4N catalytic sites that facilitates the two consecutive steps in alkaline HER reaction. More importantly, plasma treatment was further applied to the material to tune the electronic structure of the catalytic sites by creating multiple anion vacancies. The introduced O vacancies accelerated the H2O cleaving process on CeO2, while the N vacancies in Co4N optimized the H adsorption strength on the Co sites. The catalytic activity of the catalyst improved significantly after plasma treatment. It only required an overpotential of 36 mV@10 mA cm−2 for the HER operated in 1 M KOH electrolyte and provided one of the best precious metal-free catalysts ever reported. [ABSTRACT FROM AUTHOR]

The efficient production of hydrogen through water electrolysis requires stable, high-performance and rather cost-effective electrocatalysts to promote the hydrogen evolution reaction (HER). Platinum (Pt) is known to be a benchmark electrocatalyst for the HER, but its high-cost is a major obstacle for large-scale applications. Therefore, reducing Pt loading on electrodes, with a minimal influence on the electrochemical performance is of significant importance. Here, we report on the effective utilization of Pt through a simple two-step magneto-electrodeposition synthesis method, leading to the formation of uniformly dispersed Pt/NiCu electrocatalysts with an excellent catalytic activity. Under optimum conditions, NiCu substrates are fabricated under a vertical static magnetic field of 0.5 T, followed by pulsed electrodeposition of Pt under the same magnetic field. The electrocatalyst (0.5 T NiCu + 0.5 T Pt) exhibits a high stability and superior HER activity, characterized by low overpotentials of 10.6, 54.6, and 87.8 mV obtained at current densities of 10, 100, and 200 mA cm−2, respectively, accompanied by a small Tafel slope of 13.4 mV dec−1 in alkaline media (1 M KOH). This work provides a new approach enabling the optimum utilization of Pt-based electrocatalysts employed for the HER. [ABSTRACT FROM AUTHOR]

In this paper, a Co--Fe LDO catalyst was prepared by combining K2Cr2O7 and Cr(NO3)3 to modify the LDH precursor. The catalytic activity of NOx and o-DCB was systematically studied, and the effect of gas composition on the catalytic activity was investigated. The prepared Cr (0.25)/Co--Fe LDO catalyst showed the best catalytic performance, with conversion efficiencies of NOx and o-DCB of 89.0% and 81.6% at 250 °C, respectively. The catalysts were characterized by XRD, BET, SEM, XPS, H2-TPD and NH3-TPD to explore the reaction activity. In addition, the interaction between NH3-SCR and o-DCB oxidation was investigated by changing the gas atmosphere. The results showed that the inhibition at low temperature (< 200 °C) could be attributed to the residues of the by-products of incomplete oxidation. The further oxidation of NO to NO2, and the dissociation of NH3 are the reasons for the mutual promotion of the two reactions in the middle and high temperature sections. Water vapor has little effect on the reaction and the introduction of SO2 will cause irreversible inactivation of the catalyst. [ABSTRACT FROM AUTHOR]

The development of oxygen reduction reaction (ORR) catalyst that are affordable and long-lasting is crucial for the expansion of energy conversion applications. In this study, we synthesized a ZnO–NiO/reduced graphene oxide hybrid electrocatalyst by using the co-precipitation method. X-ray diffraction (XRD), thermogravimetric analysis (TGA), and Brunauer–Emmett–Teller (BET) analysis were used to characterize the synthesized ZnO–NiO/rGO hybrid catalyst. The XRD analysis showed that ZnO had a wurtzite structure, whereas the phase of NiO had a cubic structure. The TGA and BET investigations of the hybrid catalyst revealed its excellent thermal stability and large specific area (395.8 m2 g−1) compared to bare catalysts. Through transmission electron microscopy (TEM) analysis, we observed that ZnO nanorods and NiO nanoparticles are distributed evenly on the rGO surface. The electrochemical analysis showed that the ZnO–NiO/rGO hybrid catalyst had highly efficient catalytic activity for the ORR. It had a high limiting current density (7.1 mA cm−2), a positive onset potential (0.95 V), a low rate of H2O2 formation (less than 15%), and long-term stability. The oxygen reduction process on the ZnO–NiO/rGO hybrid catalyst was demonstrated to occur via a highly efficient 4e− mechanism using rotating ring-disk and rotating disk electrode investigations. The ZnO–NiO/rGO hybrid catalyst demonstrated significant promise as an expensive metal-free catalyst for alkaline fuel cell cathodes. [ABSTRACT FROM AUTHOR]

Transition metal/nitrogen-doped carbon catalysts (M–N–C) show superior catalytic activity in electrocatalytic CO2 reduction due to their high atomic efficiency. In this work, a series of electrocatalysts with cobalt phthalocyanine (CoPc) highly dispersed on M–N–C were prepared. Compared to the pure M–N–C materials, all CoPc/M–N–C catalysts showed a significantly enhanced activity for CO2 reduction and suppressed hydrogen evolution reaction. Among these catalysts, CoPc/Fe–N–C exhibits an outstanding activity and selectivity for CO2 reduction with 99% faradaic efficiency for CO at a potential of −0.48 V vs. RHE. Obviously, such a composite strategy is considered as one of the effective methods to improve the selectivity of CO2 to CO. [ABSTRACT FROM AUTHOR]

It is highly urgent to develop efficient and stable non-precious metal electrocatalysts for water splitting. Here, we have successfully prepared a phytic acid (PA)-treated NiFe layered double hydroxide (LDH) catalyst. NiFe-LDH(PA) exhibits excellent catalytic activity towards the hydrogen evolution reaction (HER), the oxygen evolution reaction (OER), and overall water splitting (OWS) (η10 = 112 mV and η100 = 198 mV for the HER, η100 = 260 mV for the OER, and 1.69 V for OWS @ 100 mA cm−2) as well as remarkable stability during long-term testing (100 h for the HER, 90 h for the OER, and 100 h for OWS). The PA treatment accelerates the catalytic kinetics of NiFe-LDH(PA) and exposes more active sites, leading to enhanced charge transfer. This work demonstrates the significant potential of organic small molecules in modifying the performance of conventional catalysts. [ABSTRACT FROM AUTHOR]

High transformation of the propane and CO2 reaction to propylene (PDH–CO2) is impelled by the reverse water–gas shift entails strong catalysts toward the reverse water–gas shift (RWGS) as well as propane dehydrogenation (PDH). A series of Co-modified Fe2O3–ZrO2 with proportions of 3–9 wt% (nCoFe–ZrO2) were synthesized using an oxalate coprecipitation method and their catalytic activity for PDH–CO2 at 550 °C was studied. 7CoFe–ZrO2 displayed the highest conversion to both CO2 and propane (37.6% and 47.4%) and propylene yield (38.1%) at a lower apparent activation energy. The interaction between Co species and Fe species and its effects on the active Fe3O4 and the adsorption of propane/CO2 were revealed using XRD, UV-Vis DRS, SEM/TEM, XPS, NH3/CO2/C3H8-TPD, and H2-TPR analysis. With Co-modification, the reduction of Fe2O3 to Fe3O4 was enhanced, which accelerated RWGS in addition to PDH. The key role of the *OOCH intermediate for promoting PDH and RWGS during PDH–CO2 reaction was traced through in situ DRIFTS characterization. [ABSTRACT FROM AUTHOR]

Herein, we aimed to synthesize three organic–inorganic hybrids (DILPOM-1/2/3), developed from the assembly of –SO3H-functionalized dicationic imidazolium ionic liquids having variable methylene connecting spacers with inorganic 12-molybdophosphoric acid. The hybrids DILPOM-1/2/3 were 2-methyl-1-(3-(2-methyl-3-sulfo-1H-imidazol-3-ium-1-yl)propyl)-3-sulfo-1H-imidazol-3-ium phosphomolybdate, 2-methyl-1-(4-(2-methyl-3-sulfo-1H-imidazol-3-ium-1-yl)butyl)-3-sulfo-1H-imidazol-3-ium phosphomolybdate, and 2-methyl-1-(12-(2-methyl-3-sulfo-1H-imidazol-3-ium-1-yl)dodecyl)-3-sulfo-1H-imidazol-3-ium phosphomolybdate. The incorporation of various lengths of connecting spacers made their thermal stability window wider, as verified by thermogravimetric analysis, and thus, they could be used as efficient catalysts in high-temperature reactions. The extent of hydrogen bond interactions within the –SO3H group and the PMo12O403− anion strategically controlled the acidic sites and together with the methylene linkages provide a heterogeneous nature to the hybrids, making them easily recyclable and thermally stable acid catalysts. The hybrid with the longest methylene connecting spacer (n = 12) was found to be more efficient as an acid catalyst than the shorter ones in the solvent-free Michael-like addition of indole with chalcones obtained via Claisen–Schmidt condensation. [ABSTRACT FROM AUTHOR]

Electrochemical catalysts for the oxygen evolution reaction (OER) with abundant reserves, high catalytic activity, and robust stability are highly crucial for efficient electrocatalytic water splitting. Herein, we designed and synthesized non-noble metal coordinated porphyrin-based hypercrosslinked polymers (FX-M-TPP), which were characterized by SEM, TEM, and XPS. Their performance as electrocatalysts for OER was evaluated in 1 M KOH, among which FX-FeCo-TPP exhibited a minimum overpotential of 251 mV at 10 mA cm−2, with a Tafel slope of 35.2 mV dec−1 demonstrating excellent stability. By studying the intermediates in the OER process, it was revealed that the true catalytically active substances are metal hydroxides that evolved from FX-FeCo-TPP. The results of this work provide a new method for designing high-performance OER catalytic materials based on organic compounds. [ABSTRACT FROM AUTHOR]

To ensure edible oil quality and safety, herein, superior hybrid magnetic nanocomposites with an enhanced peroxidase-like activity were demonstrated, which exhibited electrochemical detection of TBHQ in edible oil. Gold nanoparticles (AuNPs) and magnetic Fe3O4 NPs were embedded in an organic framework by a simple self-assembly method to fabricate Fe3O4@Au/MOF nanocomposites validated through various characterization techniques. The effective combination of Fe3O4 NPs, AuNPs and Cu-MOF exhibited high electrocatalytic activity of Fe3O4@Au/MOF, promoting charge transfer and more sensing sites. Due to its enhanced peroxidase-like activity, Fe3O4@Au/MOF catalyzes H2O2 to generate oxidatively active radicals. On the basis of these results, the redox reaction of TBHQ can be further promoted and the accurate quantitative detection of TBHQ can be achieved. Results displayed that Fe3O4@Au/MOF employed for electrochemical sensing of TBHQ exhibited a low detection limit of 0.3323 μM (S/N = 3) in the concentration range of 1–100 M. Moreover, the results of the electrochemical assays proposed to measure TBHQ in five common edible oils show a good correlation with the actual amount added. The nanocomposite demonstrated good stability, repeatability, reproducibility and sensitivity in real samples, which ensures its practical applicability in edible oil antioxidant analysis as an electrochemical sensor. [ABSTRACT FROM AUTHOR]

The reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) has been efficiently catalyzed by in situ generated Bi0-BiOX (X = Cl, Br, I) nanocomposites in the presence of sodium borohydride (NaBH4). The hierarchical 3D arrays of precursors (BiOCl, BiOBr, and BiOI) have been synthesized by a facile coprecipitation method at ambient temperature. The metallic Bi0 is generated in situ by partial reduction of the Bi3+ ions in BiOX (X = Cl, Br, and I) mediated by NaBH4 during the conversion of 4-NP to 4-AP. In situ generated Bi0-BiOX shows better catalytic activity than Bi0-BiOX composite formed by mixing individually synthesized metallic Bi0 particles with semiconducting BiOX nanoparticles. The Bi0-BiOI nanocomposite demonstrated higher catalytic activity (kapp = 0.529 min-1) compared to Bi0-BiOCl (kapp = 0.095 min-1) and Bi0-BiOBr (kapp = 0.098 min-1) due to its efficient conversion into metallic Bi0. The approximate percentage composition of in situ generated metallic Bi0 on the surface of BiOCl, BiOBr, and BiOI is nearly 10, 17, and 25%, respectively. Further, the reduction of 4-NP has been completed within 24, 22, and 6 minutes by in situ generated Bi0-BiOCl, Bi0-BiOBr, and Bi0-BiOI nanocomposites from BiOCl, BiOBr, and BiOI, respectively. Extensive studies have been conducted to generate a better understanding of the actual catalytic sites present on the surface of the catalysts. [ABSTRACT FROM AUTHOR]

Reducing the utilization of precious metals and minimizing their depletion has been a pivotal concern in precious metal catalyst research. Hence, we employed a wet impregnation method to fabricate hollow carbon and silicon nanospheres (PdFe/NxC@mSiO2), encapsulating PdFe bimetallic nanoparticles. These bimetallic nanoparticles were enclosed within the hollow spheres, forming an alloy facilitated by nitrogen anchoring. The Pd4Fe1/NxC@mSiO2 catalyst exhibited enhanced dispersion of Pd, strengthened metalcarrier interaction, and superior ability for CO adsorption enrichment compared to single Pd catalysts. In situ DRIFTS analysis further revealed that the PdFe alloy catalysts, prepared via Fe doping, exerted reduced force on CO and improved CO insertion efficiency. Consequently, the Pd4Fe1/NxC@mSiO2 catalyst demonstrated heightened catalytic activity. In comparison to the individual Pd catalyst, this catalyst showed exceptional catalytic activity in the acetylene dialkoxycarbonylation process, with strong selectivity for 1,4-dicarboxylate (485%) and considerable acetylene conversion (490%). Moreover, this catalyst displayed remarkable recyclability, remaining active even after five cycles. [ABSTRACT FROM AUTHOR]

The support is pivotal for stabilizing single metal atoms and contributes to enhance the catalytic activity of single-atom catalysts. With the merits of versatile structures, tailored electronic structure, as well as high stability, manganese oxide octahedral molecular sieve (OMS-2) can be used as an ideal support to immobilize single atoms. Herein, we report a single-atom Pd catalyst (Pd1–OMS-2) that can afford a silane conversion of above 99% with silanol selectivity of over 99% using water as oxidant under mild conditions, outperforming the original OMS-2. The as-synthesized catalyst exhibits great functional group tolerance and good catalyst stability without aggregation after reaction. And the enhanced catalytic activity is attributed to the decoration of atomic Pd and the increase in content of oxygen vacancies. Characterization of Pd1–OMS-2 indicates that the highly dispersed Pd species is trapped into the framework of OMS-2 by substituting Mn ions, which results in the formation of Pd–O bonds with the adjacent O atoms. [ABSTRACT FROM AUTHOR]

New heteroleptic dppe appended Co(III)-dithiocarbamate (dtc) complex cations with compositions [Co(S2CNEt2)2(dppe)](PF6) (Co-Et), [Co(S2CNPri2)2(dppe)](PF6) (Co-Pr) and [Co(S2CNBun2)2(dppe)](PF6) (Co-Bu) have been synthesized and characterized by microanalysis, spectroscopic methods and crystallographic analysis. The single crystal X-ray diffraction results indicated that in all three complexes, the coordination environment around Co(III) is distorted octahedral and Co(III) is coordinated to four sulfur centers of the two dtc ligands and the two phosphorus centers of the dppe ligand. These complexes serve as precursors to yield cobalt sulfide/cobalt phosphide nano-composites dCo-Et, dCo-Pr and dCo-Bu by solvothermal decomposition of Co-Et, Co-Pr and Co-Bu, respectively. The decomposed materials have been characterized by PXRD and SEM-EDAX and explored as potential electrocatalysts for both oxygen evolution and hydrogen evolution reactions in basic and acidic media, respectively. Catalytic activity is dependent on the precursor complex and best OER and HER activities are observed for dCo-Bu with an η10 of 230 mV and a Tafel slope of 192.11 mV dec−1 for the OER and an η10 of 470 mV and a Tafel slope of 126.21 mV dec−1 for the HER. [ABSTRACT FROM AUTHOR]