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This work reports a practical approach for C−O and C−C bond formation reactions catalysed by Pd nanoparticles supported on Luffa sponge (PdNPs@LS).PdNPs@LS were prepared via a green route in‐situ by using ethanol as solvent, and lignin content present in the luffa sponge could work as an effective reducing reagent to reduce Pd(II) to Pd(0) without any harsh chemical used for reduction. The bio‐based support used i. e. Luffa sponge extracted from the waste feedstock of Luffa guard in a simple filtration method is a cheap, biodegradable, abundant and renewable source with netting‐like three‐dimensional porous structure. Without significant loss of its activity the PdNPs@LS could be easily recovered and recycled for at least three times. The catalyst is characterized by FT‐IR, TGA, SEM‐EDX, TEM, and XPS analyses. [ABSTRACT FROM AUTHOR]

Co-B catalyst, W-modified Co-B (Co-W-B) catalyst, and Mo-modified Co-W-B (Co-W-Mo-B) catalyst powders were synthesized via chemical reduction of metal salt solutions at room temperature. The optimal hydrogen production rate was obtained when the ratio of the reducing agent (NaBH4) to the metal solution was 4:1. Among the ternary catalysts, the Co0.1-W0.9-B catalyst showed the optimal hydrogen production rate when the content of W doping was 0.9. Furthermore, the hydrogen production rate of the quaternary catalyst was enhanced when the content of Mo doping was 0.075, denoted as Co0.1-W0.9-Mo0.075-B. The catalyst powders were characterized by SEM, XRD, XPS, and BET. The hydrogen production rates of the Co-B catalyst, Co0.1-W0.9-B catalyst, and Co0.1-W0.9-Mo0.075-B catalyst were investigated for the decomposition of alkaline sodium borohydride (NaBH4) in a water–ethanol mixture solution. The Co0.1-W0.9-Mo0.075-B catalyst exhibited the highest hydrogen production rate compared to Co-B and Co0.1-W0.9-B catalyst powders. The optimal hydrogen production rate of the Co0.1-W0.9-Mo0.075-B catalyst is 4600 ml·min−1·g−1, which is nearly 1.9 times higher than that of the Co-B catalyst. Moreover, the Co0.1-W0.9-Mo0.075-B catalyst exhibited good stability, retaining 73% of its catalytic activity after five cycles, and had a low apparent activation energy of 41.51 kJ·mol−1. [ABSTRACT FROM AUTHOR]

Molybdenum‐ or tungsten‐dependent formate dehydrogenases have emerged as significant catalysts for the chemical reduction of CO2 to formate, with biotechnological applications envisaged in climate‐change mitigation. The role of Met405 in the active site of Desulfovibrio vulgaris formate dehydrogenase AB (DvFdhAB) has remained elusive. However, its proximity to the metal site and the conformational change that it undergoes between the resting and active forms suggests a functional role. In this work, the M405S variant was engineered, which allowed the active‐site geometry in the absence of methionine Sδ interactions with the metal site to be revealed and the role of Met405 in catalysis to be probed. This variant displayed reduced activity in both formate oxidation and CO2 reduction, together with an increased sensitivity to oxygen inactivation. [ABSTRACT FROM AUTHOR]

The transition-metals carbon catalysts belong to intensively studied alternatives to the Pt-based catalysts promoting the oxygen reduction reaction (ORR) in electrochemical fuel cells (FCs). Commonly studied Fe,Co–N–C composites are usually obtained through pyrolysis and used as such or after a chemical post-treatment with an oxidizing agent. This treatment is applied to remove inactive metal species, thus, promoting the electrochemical activity. The impact of an oxidizing agent is poorly addressed in the literature, while its nature may negatively affect the catalyst's performance. Herein we report the first comparative study on the effect of post-treatment with the most common oxidizing agents such as HCl, HNO 3 , H 2 SO 4 and H 2 O 2 , on the structural and electrochemical properties of the Fe,Co–N–C catalyst. The catalyst is made by pyrolysis of the Co,Zn-ZIF metal-organic framework enriched with iron and nitrogen. Its structure was observed withstanding the action of mineral acids but suffers from hydrogen peroxide. The treatment with either nitric or chloric acid may improve the electrochemical performance up to 4%, while other agents decrease that by 6% and slow down the ORR rate. These findings are useful for the careful design of post-treatment procedures for carbon catalysts. • The Fe,Co–N–C carbon-based catalyst was obtained from Fe,Co-ZIF-8 MOF via pyrolysis at 700 °C in an inert atmosphere. • The Fe,Co–N–C catalyst was treated with four oxidizing agents - chloric, nitric and sulfuric acids, and hydrogen peroxide. • Structural and compositional changes were assessed with multi-technique characterization of the catalysts. • The catalysts treated with nitric and chloric acids demonstrated improved performance for ORR in an acidic medium. [ABSTRACT FROM AUTHOR]

The development of high-efficient and low-cost catalysts is crucial for promoting KBH 4 hydrolysis to produce hydrogen. Herein, ZIF-67 supported cobalt-molybdenum-nickel based boride (Co–Mo–Ni–B/ZIF-67) nanocomposites with dandelion-like morphology were designed as catalysts of KBH 4 hydrolysis reaction and were synthesized via the chemical reduction process. Moreover, the element ratio and the loading amount of Co–Mo–Ni–B were optimized, and effects of KBH 4 concentration, KOH concentration, and reaction temperature on catalytic performances were studied. As expected, ZIF-67 substrate avoids the agglomeration of amorphous Co–Mo–Ni–B, and the synergy between ZIF-67 and uniformly dispersed Co–Mo–Ni–B active substances accelerates hydrogen generation rate. As a result, the maximum hydrogen generation rate of 17400 mL min−1 g−1 is achieved with the optimized KOH concentration of 10% and KBH 4 concentration of 6% at the reaction temperature of 30 °C. In addition, Co–Mo–Ni–B/ZIF-67 exhibits moderate durability performance with a cyclic retention rate of 51.9 % after five cycles. This dandelion-like structure design provides an idea for the development of efficient catalyst for hydrolysis of borohydrides. [Display omitted] • Co–Mo–Ni–B/ZIF-67 is prepared as catalysts of KBH 4 hydrolysis reaction. • The dandelion-like structure of Co–Mo–Ni–B/ZIF-67 exhibits excellent catalytic performance. • Co–Mo–Ni–B/ZIF-67 with optimized composition displays the hydrogen generation rate of 17400 mL min−1 g−1 at 30 °C. • ZIF-67 substrate avoids the agglomeration of amorphous Co–Mo–Ni–B. [ABSTRACT FROM AUTHOR]

The process of hydrolysis of sodium borohydride is a new and clean method for the production of hydrogen. In this study, cobalt nanoparticles were synthesized by the mechanochemical and chemical reduction methods, and their catalytic performance was compared. The effect of using different cobalt precursors and reducing agents was investigated for the sample prepared via the chemical reduction method. The results showed that the cobalt catalysts synthesized through the chemical reduction method possessed better catalytic performance. Also, the sample prepared using cobalt nitrate and sodium borohydride had a higher hydrogen generation rate (HGR), which was equal to 3272.7 ml min−1g−1. The kinetics of the cobalt catalyst in the process have also been investigated, revealing that the rate of hydrogen production is dependent on the concentrations of sodium borohydride and sodium hydroxide, the catalyst dosage, and the process temperature. The crystal size of this catalyst was 21.6 nm with spherical agglomerated particles. The BET area of the best sample and its activation energy was equal to 11.18 m2g-1 and 22.3 kJmol-1, respectively. This catalyst was also stable in successive cycles. [Display omitted] • Cobalt catalysts were synthesized via the mechanochemical and chemical reduction methods. • The catalytic performance of the cobalt catalyst in the hydrolysis of NaBH 4 was high. • The hydrogen generation rate of the Co–B catalyst was 3272.7 mLmin−1g−1 at 30 °C. • The activation energy of the Co–B catalyst is lower compared to that of other cobalt-based catalysts. [ABSTRACT FROM AUTHOR]

Developing high-activity catalysts for the hydrolysis of ammonia borane (NH 3 BH 3 ; AB) is a crucial and urgent task, which is presently considered an effective strategy for hydrogen generation in the applications of portable proton exchange membrane fuel cells (PEMFCs). In this study, carbon nanotubes (CNTs) were modified by self-growth of metal-organic frameworks (MOFs) on their surfaces. As self-sacrificial templates, the carbonization of cobalt and nitrogen containing MOFs led to the modification of CNT. Subsequently, cobalt was transformed into cobalt phosphide (Co 2 P) via phosphatization to form Co 2 P/N co-decorated CNTs (NCP-CNTs). Ru/NCP-CNT catalysts were obtained by loading ruthenium nanoparticles (NPs) using a chemical reduction method and their catalytic performance for H 2 production via the hydrolysis of AB was systematically investigated. Ru/NCP-CNTs exhibited excellent catalytic activity, with an initial high turnover frequency (TOF) of 193.9 mol H2 ·mol Ru −1·min−1 and a low activation energy of 32.4 kJ·mol−1. The incorporation of Ru NPs and their excellent synergistic effect with the NCP-CNT supports can explain the improved performance. This work provides an updated approach for fabricating low-cost and high-efficiency catalysts for the hydrolysis of AB. • The Ru/NCP-CNT catalysts were successfully prepared. • Ru/NCP-CNT exhibited superior catalytic activity toward AB hydrolysis. • Low E a of 32.4 kJ·mol−1 and high TOF of 193.9 mol H2 ·mol Ru −1·min−1 were achieved. • Synergistic effect between Ru NPs and NCP-CNT was responsible for the improved performance. [ABSTRACT FROM AUTHOR]

• Based on the constant potential implicit solvent model, a realistic electrocatalytic environment was simulated. • The ORR activity of S-coordinated FeN 4 was simulated using a constant potential implicit solvent model. • It was found that FeN 4 S2 exhibited the highest activity under -2e conditions with an overpotential of 0.39V. • The high electronegativity of S enhances the valence state of Fe, weakens adsorption of *OH, and promotes the ORR process. The widespread application of S doping in Fe-N-C materials aims to enhance the catalytic activity for oxygen reduction reactions (ORR). However, the current doping strategies are primarily centered on the first coordination layer encompassing Fe atoms. Consequently, this study employs first-principles calculations to compute the formation and binding energies of FeN 4 doped with S atom. It further delves into the influence of diverse doping sites on catalyst stability and meticulously analyzes the configurations and corresponding ORR activities of four catalysts, namely FeN 4 S-N (Number=0∼3), utilizing a constant-potential implicit solvent model to simulate authentic electrocatalytic environments. The findings reveal that under vacuum conditions, FeN 4 S1 exhibits the utmost ORR activity, boasting a potential of 0.53 V. Conversely, within the constant-potential implicit solvation model, FeN 4 S2 emerges as the catalyst with the highest ORR activity, achieving a potential of 0.39 V. Therefore, calculations leveraging the constant-potential solvation model offer more realistic insights into catalyst design, thereby guiding the development of superior catalysts. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel organbentonite-based Ni-B catalyst doped with the metal La has been obtained. • La doping inhibited the aggregation of the catalyst and has more active centers. • Use of ultrasound effectively accelerated the CTH process of FAMEs. • The kinetics and thermodynamics of the FAMEs hydrogenation have been researched. • The possible reaction mechanism of ultrasound-assisted CTH has been proposed. In this work, an efficient organobentonite-based Ni-La-B composite catalyst (Ni-La-B/OB) was synthesized through impregnation and chemical reduction method using cetyltrimethylammonium bromide (CTAB)-modified bentonite as support and along with the addition of the metal additive La, and then was employed as catalyst for the ultrasound-assisted catalytic transfer hydrogenation (CTH) reaction of fatty acid methyl esters (FAMEs). The characterization results suggested that the inclusion of La resulted in the generation of additional active site. Under the conditions of the mass ratio of solvent water, hydrogen donor isopropanol and FAMEs of 80:28:5 and the catalyst dosage of 10 wt.%, the conversion ratio of C18:2 (CR C182) reached 76.68 %, and the iodine value (IV) decreased from the initial value of 146.7 to 84.01. Kinetics and thermodynamics research showed that ultrasound-assisted CTH of FAMEs followed pseudo-first-order kinetics and was endothermic. Meanwhile, a possible reaction mechanism of the catalyst on CTH of FAMEs was proposed. The Ni-La-B/OB composite catalyst underwent four recirculated cycles, and no significant deactivation was observed. In addition, ultrasound-assisted CTH significantly improved the hydrogenation effect and shortened the reaction time in comparison with the conventional method. The Ni-La-B/OB composite was found to be an efficient hydrogenation catalyst for CTH, and the doping of La significantly enhanced the catalytic activity. [ABSTRACT FROM AUTHOR]

The production of tetrahydrofurfuryl alcohol (THFAL) from biomass-derived furfural (FF) via one-pot hydrogenation is challenging owing to the high hydrogen pressure and temperature requirements of the system. In this study, a hydrothermal method is used to synthesize a series of wrinkled silica (KCC-1) supports having different morphologies and textural properties by modulating the cetylpyridinium bromide hydrate (CPB)/tetraethyl orthosilicate (TEOS) ratio. Subsequently, Pd-supported KCC-1 catalysts are fabricated along with a Pd/SiO 2 catalyst (for comparative studies) via a chemical reduction method. Interestingly, the morphological features of the supports, such as the specific surface area, pore size, and Pd anchoring sites, differed significantly for different CPB/TEOS ratios. Among the synthesized catalysts, Pd/KCC 0.3, with the lowest proportion of Pd nanoparticles deposited on the external porous surface, exhibits the highest catalytic activity, owing to its large specific surface area and moderate pore size. Moreover, it shows the highest FF conversion of 100% and THFAL selectivity of 85% in 6 h at 50 °C under 20 bar H 2. • KCC-1 supports with different morphologies are prepared by tuning CPB/TEOS ratios. • The correlation between the morphological features and the catalytic activity of Pd-based catalysts have been investigated. • Pd/KCC-1 catalsyts show higher selectivity for one-pot hydrogenation of furfural compared to Pd/SiO 2. • Pd/KCC 0.3 catalyst with a large surface area and low fiber density showed the highest selectivity to THFAL. [ABSTRACT FROM AUTHOR]

The influence of the composition of the copper complex and the structure of the ligand on the selectivity of continuous hydrogenation processes of dicyclopentadiene and nitrobenzene, as well as the reductive alkylation of nitrobenzene with isobutanol, up to the production of various reduction products under the same conditions with a selectivity of up to 100%, was discovered. [Display omitted] The reaction of copper(II) acetate with furoic acids (2Hfur / 3Hfur) and imidazole (Im) in methanol resulted in mononuclear complexes [Cu(fur) 2 (Im) 2 (H 2 O)]·L (fur- = 2fur- (1 , 2), 3fur- (3); L = MeCN (1)) whose structures were determined by direct single crystal X-ray analysis. It was found for the first time that copper nanoparticles immobilized on the surface of γ-Al 2 O 3 obtained by chemical reduction of 1 , 2 and 3 (pre-deposited on the surface from solution) with sodium tetrahydroborate show high selectivity of mono- and dihydrogenation of tricyclo[5.2.1.02,6]deca-3,8-diene (dicyclopentadiene, DCPD). The catalytic activity tests show a high selectivity (97 %) of the catalyst obtained from an ethanolic solution of complex 1 in the reaction of partial hydrogenation to DHDCPD under continuous process conditions even at high conversion values (up to 96 %) and with an excess of hydrogen, whereas the catalyst obtained from an aqueous solution of complex 1 showed 98 % total hydrogenation product (THDCPD) selectivity. The catalysts based on all the complexes 1 – 3 were successfully used in reactions of nitrobenzene (NB) reduction to aniline (AN) and in the reductive alkylation of nitrobenzene with isobutanol (i -BAN) 100 % yields of aniline and N -isobutylaniline were obtained at LHSV 0.16 h−1. [ABSTRACT FROM AUTHOR]

• A value-added and efficient technology for recycling spent Ag-Al 2 O 3 catalyst is proposed. • High-value-added spherical silver powder is synthesized by a simple chemical reduction method. • A fitted mathematical model of particle size for silver powder is obtained. • The interactions between the factors are investigated. The spent Ag-Al 2 O 3 catalyst is an important silver secondary resource due to its high content of Ag. However, the most commonly used nitric acid leaching method produces toxic and harmful NO x gases. Herein, a novel clean method was proposed to treat the spent Ag-Al 2 O 3 catalyst using the green leaching agent cerium ammonium nitrate instead of nitric acid to effectively avoid the generation of toxic NO x gases. More importantly, value-added monodisperse micro-sized uniform spherical particles were synthesized directly from the leaching solution by a simple chemical reduction method. The influence of leaching conditions on the leaching ratio of Ag and leaching kinetics were discussed in detail. The response surface methodology was applied to optimize the synthesis parameters of silver powder and explore the interactions between the synthesis process parameters. Under the optimal leaching parameters, the leaching ratio of Ag reached 99.69 %. The leaching kinetic analysis of leaching indicated that the leaching reaction of spent Ag-Al 2 O 3 catalyst was controlled by chemical reaction. By the response surface methodology design, a fitted mathematical model of the particle size for silver powder and the optimum synthesis parameters of silver powder were obtained. The optimum synthesis parameters of silver powder were as follows: [Fe2+] = 1.08 mol/L, [Ag+] = 1.01 mol/L, and dispersant dosage of 2.05 wt%. The average experimental particle size of 1.337 μm was very close to the predicted value of 1.343 μm obtained from the fitted model, indicating that the fitted model of particle size for silver powders was very good. This process not only provides a clean and value-added method for recycling the spent Ag-Al 2 O 3 catalyst, but also helps to promote the balanced and high-value utilization of high-abundance cerium. [ABSTRACT FROM AUTHOR]