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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]

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]

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]

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]

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]

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]

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]

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 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]

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]

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]

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]

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]

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]

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]

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]

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]

Precious metal nanoparticles (NPs) are attractive for use in the field of catalysis because of their precisely controlled sizes and shapes. However, NPs exhibit insufficient anti-sintering properties under common operating conditions due to their poor thermal stability at elevated temperatures. In this paper, the preparation of noble metallic NPs (Pd and Au) incorporated inside the pores of an SBA-15 support via a sol-immobilization method, which prevents their aggregation, is reported. The Pd NPs retain their size of ∼5 nm within the channels of SBA-15, even after aging at 800 °C for three days under an air atmosphere. However, Au NPs aggregated at a temperature of calcination above 500 °C. Using a set of characterization methods comprising XRD, STEM, HRTEM, TPR, and DRIFTS analysis, it is revealed that Pd on SBA-15 exhibits better anti-sintering properties than the Au supported system. The catalytic activity and durability of M/SBA-15 (M: Pd or Au) catalysts were studied using CO oxidation with and without steam (10 vol%). Interestingly, a hydrothermally treated (Pd/SBA-15-750-H2O-3d) catalyst leads to the partial re-dispersion of Pd. This helps to attain smaller particles of ∼1.6 nm, which play a prominent role in the catalytic performance. This work provides insight into the design of sintering-resistant metal catalysts, which would be suitable for industrial applications under harsh conditions. [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]

Exploring the utilization of earth-abundant metals for essential organic transformations is highly fascinating from an industrial viewpoint. In this present study, a simple and energy efficient precipitation protocol was employed for the synthesis of hierarchical MgO microspheres that were efficiently used as catalysts in the Claisen–Schmidt condensation reaction. The hierarchical MgO microsphere catalyst was prepared via a precipitation process using Na2CO3 as a precipitating agent under green reaction conditions. The inherent properties of the synthesized MgO hydroxide and MgO microspheres were well characterized using advanced analytical and spectroscopic techniques, such as TGA, XRD, FE-SEM, EDAX, TEM/HR-TEM, FT-IR, XPS, NH3 and CO2-TPD analyses. The synthesized MgO material successfully achieved excellent inherent properties, such as high thermal stability, good crystallinity, microsphere morphology, large specific surface area, and uniformly dispersed active sites on the material surface. Using the MgO catalyst, various reaction parameters, such as the effect of catalyst dosage, temperature, time, and solvents, were examined. As a result, chalcone was obtained as a product with 100% conversion and 90% yield in the presence of green solvent ethanol under reflux conditions at 80 °C for 20 h with 20 wt% catalyst amount. The catalytic activity was truly reliant on the inherent properties of hierarchical MgO microspheres. The competent MgO microsphere catalyst showed excellent catalytic activity for aldehyde and acetophenone molecules functionalized with electron-withdrawing groups and achieved respective chalcone products with excellent yields (84–91%) under optimized reaction conditions. The prominent structural and physicochemical properties facilitated catalytic activity in the Claisen–Schmidt condensation reaction under temperate reaction conditions. Remarkably, the efficient hierarchical MgO microsphere catalyst showed excellent recyclability up to 8 consecutive cycles with insignificant loss of its initial catalytic activity under optimized reaction conditions. The characteristic results of the spent MgO catalyst showed supportive evidence for stable structural and physicochemical properties. [ABSTRACT FROM AUTHOR]

The present work describes the synthesis of a material consisting of a bisimidazolium ionic liquid supported on graphene oxide. The prepared nanocomposite was characterized by different physicochemical techniques such as FT-IR, XRD, CHN, SEM, TEM and EDAX. The synthesized nanocomposite was further utilized as an effective heterogeneous catalyst for the synthesis of tetraketone derivatives, which are biologically significant, using dimedone and aryl aldehydes as the substrates at 50 °C and a green solvent. One of the tetraketone products has been confirmed by single crystal XRD. The catalyst displayed high reaction yields, facile separation, short reaction time, good stability and recoverability up to six consecutive reaction rounds with no discernible loss in its catalytic activity. [ABSTRACT FROM AUTHOR]

A cost-effective and step-economic synthesis of pharmaceutically important 1,2-disubstituted benzimidazoles and 2,3-dihydro-1H-perimidine derivatives is accomplished without the assistance of external ligands. An environmentally friendly biogenic strategy for the synthesis of single phase δ-MnO2 NPs using the Pongamia pinnata leaf extract was adopted. The phytochemicals detected in the extract of Pongamia pinnata leaves might be responsible for the reduction of Mn(VII) to Mn(IV), which provides stability to the metal centre. The synthesized catalyst was tested for the synthesis of pharmaceutically important benzimidazole and perimidine analogues. In addition, mechanistic experiments and the plausible mechanism were discussed. The δ-MnO2 NP catalyst exhibited superior catalytic activity and high durability in the dye removal study. [ABSTRACT FROM AUTHOR]

Pt/C and SO42−/ZrO2 were mechanically mixed as the catalysts for p-aminophenol synthesis by catalytic transfer hydrogenation of nitrobenzene in water with formic acid as the hydrogen source. The effect of Pt loading and the solid acid on the reaction was investigated. PAP selectivity reached a maximum at a loading of 1 wt%. The characterization results revealed the presence of three valence states of Pt. Pt0 was beneficial for the nitrobenzene hydrogenation, while higher valence Pt contributed to the formic acid decomposition. The catalytic performance of different solid acid catalysts, including HZSM-5, Hβ, SO42−/ZrO2 and SO42−/TiO2, was compared. It was found that Lewis acid sites with strong acid strength were favorable for p-aminophenol formation, and SO42−/ZrO2 showed higher catalytic activity for the reaction. Using Pt/C + SO42−/ZrO2 as the catalyst, the reaction conditions were optimized. Under the optimal reaction conditions, the nitrobenzene conversion and the p-aminophenol selectivity were 80.0% and 47.6%, respectively. The reaction mechanism was also proposed based on the main by-products of the reaction. [ABSTRACT FROM AUTHOR]

Zn–air batteries have garnered significant interest due to their high capacity, economical cost, and eco-friendly nature. The pursuit of non-noble metal cathode catalysts that offer high activity, exceptional durability, and cost-efficiency as alternatives to noble metal platinum is a prominent research focus. In this investigation, a nitrogen-doped carbon material predominantly constituted of pyridinic nitrogen and graphitic nitrogen was synthesized utilizing the polymer of hexaaminobenzene and hexaketocyclohexane as precursors. In a 0.1 M KOH electrolyte, this catalyst demonstrated ORR catalytic activity on par with commercial Pt/C and showcased enhanced stability compared to Pt/C. When incorporated as a cathode catalyst in a zinc–air battery, the battery exhibited stable discharge for 95 hours at a current density of 5 mA cm−2, achieving a specific capacity as high as 730 mA h g−1. Its discharge efficacy remained consistent even following multiple replacements of the anode zinc plate, facilitating the repeated use of the zinc–air battery. This research underpins the technical foundation and theoretical framework for the advancement of novel carbon-based catalysts characterized by straightforward production techniques, affordability, and superior activity and resilience. [ABSTRACT FROM AUTHOR]

Adjusting the morphology of Pt-based catalysts to increase the utilization of noble metal Pt towards the methanol oxidation reaction has become an efficient method to improve the catalytic performance. In this work, 3D hydrangea-like Fe2P–CoP nitrogen-doped carbon (Fe2P–CoP–NDC) with large specific surface area was assembled by means of solvothermal and pyrolytic phosphorization. The hydrangea-like Pt/Fe2P–CoP–NDC catalyst prepared by depositing platinum nanoparticles on Fe2P–CoP–NDC exhibits a better mass activity of 917 mA mgPt−1 during the methanol oxidation reaction, which is 2.33 times higher than that of commercial Pt/C (393 mA mgPt−1), and the Pt/Fe2P–CoP–NDC sample also shows excellent durability after 1000 cycles. The enhanced catalytic activity of the Pt/Fe2P–CoP–NDC catalyst can be ascribed to the synergetic effect of NDC, metal phosphide and Pt (electron transfer from neighboring atoms to Pt), which changes the surface electronic structure of Pt and maximizes its utilization, consequently weakening the adsorption of CO during methanol oxidation. Furthermore, the unique 3D hydrangea-like Fe2P–CoP–NDC can effectively improve the interaction between Pt and support, promoting the overall catalytic stability of the catalyst. [ABSTRACT FROM AUTHOR]

Attapulgite, as a versatile clay, can be constructed as an integral monolith through a 3D printing strategy to promote practical catalytic applications. Herein, we successfully realized 3D printing of attapulgite monoliths with the superior printing effect via a direct ink writing (DIW) technique. The influence of thermal treatment on DIW attapulgite monoliths was also systematically investigated at different calcination temperatures. Wherein, related characteristic changes of DIW attapulgite monoliths under thermal treatment were examined, including surface morphology, chemical properties, solidification shrinkage, rheological behaviors and compressive strength. Additionally, DIW attapulgite monoliths under thermal treatment were probed for the selective catalytic reduction of NOx with NH3 (NH3-SCR) performance, in which 3D-ATP-400 can exhibit superior low-temperature NH3-SCR activity with almost 100% NOx conversion and N2 selectivity in the range of 40–70 °C. This study can provide a facile strategy for the design and preparation of 3D-printed attapulgite monoliths with superior low-temperature NH3-SCR performance under thermal treatment. [ABSTRACT FROM AUTHOR]