Catalytic Performance Research Articles

Disentangling the catalytic origin in defect engineered 2D NiCoMoS@Ni(CN)2 core-shell heterostructure for energy-saving hydrazine-assisted water oxidation

The major hindrance to efficient electrocatalytic hydrogen generation from water electrolysis is the sluggish kinetics with corresponding large overvoltage of oxygen evolution reaction. Herein, we report a defective 2D NiCoMoS@Ni(CN)2 core-shell heterostructure derived from Hofmann-type MOF as an efficient and durable high-performance noble metal-free electrocatalyst for hydrazine oxidation reaction (HzOR) in alkaline media. The sluggish oxygen evolution reaction was replaced with a more thermodynamically favourable HzOR, enabling energy-saving electrochemical hydrogen production with 2D NiCoMoS@Ni(CN)2 acting as a bifunctional electrocatalyst for anodic HzOR and cathodic hydrogen generation. Operating at room temperature, the two-electrode electrolyzer delivers 100 mA cm−2 from a cell voltage of just 257 mV, with strong long-term electrochemical durability and nearly 100% Faradaic efficiency for hydrogen evolution in 1.0 M KOH aqueous solution with 0.5 M hydrazine. The density functional theory (DFT) was employed to investigate the origin of catalytic performance and showed that high vacancy creation within the heterointerface endowed NiCoMoS@Ni(CN)2 with favourable functionalities for excellent catalytic performance.

Non-thermal plasma-catalytic ammonia synthesis over alumina-supported iron catalyst: Insights into the effect of alumina calcination temperature

Non-thermal plasma-catalytic ammonia synthesis (NTPCAS) has been regarded as a promising route to store hydrogen by utilizing renewable electricity. Alumina is a suitable support of the catalysts in NTPCAS and its properties can influence the performance of catalysts remarkably. In this study, the influence of the alumina calcination temperatures (Tc) on the catalytic performance of Fe-Al-x (x represents the value of Tc) was analyzed in a dielectric barrier discharge (DBD) reactor for NTPCAS. The results suggested that an increase in Tc transforms the alumina crystalline from γ phase to α phase. The best performance with a synthesized ammonia concentration of 11833 ppm was achieved over Fe-Al-900 with coexisting γ and θ phases of alumina under N2: H2 = 1:1 and SEI = 37.05 kJ/L conditions, which was 37 % higher than that of Fe-Al-800 with only γ phase. In addition, the larger Tc (i.e. 1100 and 1200 °C) decreased the specific surface area, increased the mean catalyst particle size, and led to the non-uniform dispersion of Fe species. The NH3-TPD and XPS studies suggested that an increase in Tc could influence the surface acidity and oxygen vacancy concentration of Fe catalysts, which were crucial to adjusting the catalytic activity for NTPCAS. This study clarifies the value of a suitable design of support of catalysts for improving NTPCAS.

Terbium- and samarium-doped Li2ZrO3 perovskite materials as efficient and stable electrocatalysts for alkaline hydrogen evolution reactions.

The preparation of highly active, rare earth, non-platinum-based catalysts for hydrogen evolution reactions (HER) in alkaline solutions would be useful in realizing green hydrogen production technology. Perovskite oxides are generally regarded as low-active HER catalysts, owing to their unsuitable hydrogen adsorption and water dissociation. In this article, we report on the synthesis of Li2ZrO3 perovskites substituted with samarium and terbium cations at A-sites for the HER. LSmZrO3 (LSmZO) and LTbZrO3 (LTbZO) perovskite oxides are more affordable materials, starting materials in abundance, environmentally friendly due to reduced usage of precious metal and moreover have potential for several sustainable synthesis methods compared to commercial Pt/C. The surface and elemental composition of the prepared materials have been confirmed by X-ray photoelectron spectroscopy (XPS). The morphology and composition analyses of the LSmZO and LTbZO catalysts showed spherical and regular particles, respectively. The electrochemical measurements were used to study the catalytic performance of the prepared catalyst for hydrogen evolution reactions in an alkaline solution. LTbZO generated 2.52mmol/g/h hydrogen, whereas LSmZO produced 3.34mmol/g/h hydrogen using chronoamperometry. This was supported by the fact that the HER electrocatalysts exhibited a Tafel slope of less than 120mV/dec in a 1.0M alkaline solution. A current density of 10mA/cm2 is achieved at a potential of less than 505mV. The hydrogen production rate of LTbZO was only 58.55%, whereas LSmZO had a higher Faradaic efficiency of 97.65%. The EIS results demonstrated that HER was highly beneficial to both electrocatalysts due to the relatively small charge transfer resistance and higher capacitance values.

Bi-doped initiates the crystal structure reconfiguration of Aurivillius, boosts piezoelectric response, and achieve PMS activation and antibiotic degradation in Bi2LaNbTiO9-BiOBr heterojunctions

Piezo-photocatalysis has been widely accepted as a research strategy for environmental treatment. However, the outstanding issues of synergistic pressure response and charge transfer are still the difficulties in this area, so it is crucial to improve these points. Doping modification of piezoelectric materials is a well-established method to enhance the piezoelectric response and promote charge transfer by modulating the crystal structure. In this study, the crystal structure of Bi4Ti3O12 has been reconstructed by double doping substitution at A and B sites, which realizes the layer change of perovskite structure and the structural distortion of MO6 (M = Ti, Nb). This change in crystal symmetry effectively enhances the piezoelectric response of the material and combined with the construction of Bi2LaNbTiO9-BiOBr (BLNT-BOB) heterojunctions, the charge distribution is dramatically improved, and the charge transfer becomes easier. Under the dual effect of heterojunction and piezo-photocatalytic coupling, the catalyst exhibited excellent catalytic performance, and the degradation rate of BhB reached 97.24% within 20min, After PMS activation, the degradation rate reached 98.65% in 16min, which was higher than that of BLNT (59.13%) and BOB (46.81%), and the reaction kinetics were improved by 5.3-fold and 7.4-fold. It also showed good degradation efficiency in the treatment of antibiotics, and the soybean sprout culture experiment provided a strong proof of the applicability of the catalyst in multiple pollutants and biocompatibility. This work provides valuable insights for designing piezoelectric photocatalytic structures and analyzing the activation mechanism of PMS.

Synthesis and Characterisation of Graphene Oxide Catalysts for Glycerol Acetylation

Glycerol in large quantities as a by-product of biodiesel production is a promising feedstock to be converted into more valuable products such as acetin. In this work, acetin converted from glycerol acetylation with acetic acid was performed over graphene oxide as a catalyst in a batch reactor. The study's objective was to evaluate the effect of sodium nitrate amount in the catalyst preparation on the catalyst's characteristics and catalytic performance. The graphene oxide (GO) catalysts were charac­terised by various tests, such as SEM-EDX for their morphology, the nitrogen adsorption capacity using Breneur-Emmet Teller (BET), structural analysis using XRD, functional group us­­ing FTIR, and catalytic activity on glycerol acetylation. The GO1, GO2, and GO3 catalysts were varied based on the NaNO3 amount in the modified Hummer method. The experiments found that the NaNO3 amount in catalyst preparation plays a vital role in GO structure formation. The GO2 catalyst has the highest performance, as indicated by the highest surface area, pore volume, and size. High glycerol conversion (94 %) and selectivity toward the interest products of triacetin (24 %) and diacetin + triacetin (83 %) were reached in 2 h of reaction using three wt.% catalysts, 110 °C reaction temperature, and 1:9 molar ratio of glycerol to acetic acid. Copyright © 2024 by Authors, Published by BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Isomeric organic ligands directing octamolybdates-linked Copper(II) functionalized complexes as active catalysts in electrochemistry and desulfurization

Two remarkable octamolybdates-based copper-organic complexes, namely, [Cu7(L)4(H2O)7(β-H2Mo8O26)]·7H2O (POM 1) and [Cu6(HX)4(β-Mo8O26)(H2O)6]·3H2O (POM 2) (H3L = 2-(pyridine-4-yl)-1H-imidazole-4,5-dicarboxylic acid; H3X = 2-(pyridine-3-yl)-1H-imidazole-4,5-dicarboxylic acid), were successfully assembled using two isomeric organic ligands under hydrothermal conditions. The two-dimensional metal-organic layers of POMs 1 and 2 were converted into three-dimensional frameworks by hexadentate β-H2Mo8O262− and tetradentate β-Mo8O264− clusters, respectively. The electrocatalytic properties of POM 1 were investigated, revealing its ability to catalyze the reduction of BrO3−, NO2− and H2O2 and the oxidation of ascorbic acid. Notably, POMs 1 and 2 demonstrated exceptional stability in organic solvents and exhibited excellent catalytic performance in oxidative desulfurization. When employed as catalysts for thioanisole oxidation, the conversion rates reached 94.5% after 150 min for POMs 1 and 99.9% after 120 min for POMs 2. In addition, their catalytic performances in model oil remained largely unchanged after five recycling cycles.

One-step synthesis of Pt@(CrMnFeCoNi)3O4 high entropy oxide catalysts through flame spray pyrolysis

High entropy oxides (HEOs) show great prospects in catalysis owing to their widely tunable component structures and ease of combination with active metals. However, the development of HEO catalysts is limited by the lack of efficient synthesis methods due to the difficulty of homogeneously mixing at least five elements. In this work, flame spray pyrolysis (FSP) is successfully employed to synthesize (CrMnFeCoNi)3O4 HEO with a single phase spinel structure in one step, which is verified by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), and energy-dispersive X-ray spectroscopy (EDS). Taking CO catalytic oxidation as a probe reaction, the Pt@(CrMnFeCoNi)3O4 HEO catalyst synthesized by FSP in one step is compared with the catalyst whose Pt is impregnated on (CrMnFeCoNi)3O4 HEO support. The FSP-made catalysts have a higher catalytic reaction rate and better redox ability, which lowers the temperature of complete CO conversion by nearly 100 °C. Furthermore, it can be observed that the flame parameters can be optimized to modify the particle size and oxygen vacancies of the HEO nanoparticles, thus enhancing the catalytic performances. This work demonstrates that FSP is an effective method for the one-step synthesis of HEO catalysts with excellent catalytic performance, providing a new perspective for the synthesis of HEO-based materials.

Quercetin-Derived Platinum Nanomaterials Influence Particle Stability, Catalytic, and Antimicrobial Performance

Quercetin-Derived Platinum Nanomaterials Influence Particle Stability, Catalytic, and Antimicrobial Performance

Preparation and photocatalytic mechanism of magnetic Ag2S/CoFe1.95Dy0.05O4 Z‐scheme heterojunction

AbstractThe synthesis of high‐efficiency magnetic composite photocatalyst by doping magnetic cobalt ferrite and compounding single semiconductor photocatalyst is a promising strategy to improve the oxidation ability of photocatalytic systems. In this paper, CoFe1.95Dy0.05O4 (CFDO) was prepared by doping Dy element into magnetic CoFe2O4, and Ag2S (AS)/CFDO with high‐efficiency magnetic photocatalyst was synthesized by compounding AS with CFDO as the substrate. The photocatalytic samples were characterized by different advanced characterization methods, and their photocatalytic degradation of methylene blue (MB) was studied. The results show that AS/CFDO exhibits higher visible light response, excellent photogenerated charge separation ability and migration efficiency, and excellent catalytic performance in the catalytic degradation system. The photocatalytic activity of AS/CFDO was the highest, and its photocatalytic degradation kinetic constant K was 2.48 and 1.54 times that of AS and CFDO, respectively. In addition, the catalyst contained in the catalytically contaminated solution can be effectively separated by an external magnetic field to achieve multiple cycles of degradation and recycling. The cyclic degradation experiments showed that AS/CFDO exhibited high degradation stability during the photodegradation process. After the fifth reuse, the degradation efficiency was still more than 88.0%. Finally, the possible photocatalytic mechanism of the samples was discussed. Therefore, this work provides an effective solution for the construction of photocatalysts with high efficiency, magnetic recovery, and cyclic degradation stability and avoids the secondary pollution of catalysts to organic wastewater. It is of great significance to create an environmentally friendly catalytic method for efficient cyclic degradation of organic wastewater.

A cocatalytic nanozyme based on metal-organic framework-embedded iron porphyrin for the sensitive detection of Salmonella typhimurium in milk

The nanozyme, acting as the signal labeling reporter, is widely employed in colorimetric immunoassays due to its exceptional catalytic activity and reliable performance. Nonetheless, when immobilized on the nanozyme's surface, there is a decline in catalytic activity, which hinders its ability to meet the escalating demand for advanced colorimetric immunoassays. Herein, we introduce a novel MILL-88@TcP nanozyme, formed by encapsulating iron porphyrins (TcP) within metal-organic frameworks (MILL-88), where the catalytic activity of TcP is fully preserved through ethanol-induced release. Leveraging the superior encapsulation capacity and enzyme-mimicking characteristics of MILL-88, the MILL-88@TcP nanozyme demonstrates a remarkable colorimetric performance, 1430-fold higher than that of MILL-88 alone. Furthermore, we developed the MILL-88@TcP nanozyme-based Enzyme-Linked Immunosorbent Assay (N-ELISA) for enhanced sensitivity in detecting Salmonella typhimurium, achieving a detection limit of 1.68 × 102 CFU/mL, approximately 500-fold enhancement compared to the traditional HRP-based ELISA (8.35 × 104 CFU/mL). Notably, the average recoveries ranged from 91.50 % to 108.50 % with a variation of 3.53 %–10.41 %, indicating high accuracy and precision. Collectively, this study highlights that the MILL-88@TcP nanozyme, with its superior catalytic performance and anti-interference capabilities, holds promise as a colorimetric labeling reporter to enhance the detection efficacy of colorimetric immunoassays and has the potential to establish a more stable and sensitive colorimetric assay platform.

Characterization and catalytic performance of rGO-enhanced MnFe2O4 nanocomposites in CO oxidation

In this work, different weight ratio of reduce graphene oxide (rGO) incorporated manganese ferrite (MnFe2O4) is successfully prepared using reduction photolysis method. To have good spacing of layer, expanded graphite was employed for synthesis of graphene oxide by Hummer modified method. The synthesized rGO/MnFe2O4 nanocomposite was characterized by FTIR, EDX, Raman, XRD, BET, XPS, TGA, TPR and FESEM, while the magnetic properties are investigated employing VSM technique. The catalytic results demonstrated that the MnO2 and Fe2O3 have low catalytic activity and it is not active at temperature lower than 130 °C. The highest efficiency was noted for the MnFe2O4 nanocomposite. The demonstrated results appeared that the doped of rGO inter MnFe2O4 considerably improved the efficiency for oxidation of CO. On the other hand, the highest conversion was obtained for the 1 wt% rGO doped MnFe2O4 and it displayed a CO conversion of 100 % at 80 °C. 1 wt% rGO/MnFe2O4 with conversion 98% CO demonstrated higher activity compared with Fe2O3 and MnFe2O4. On the other hand, the results exhibited that the 1 wt% rGO/MnFe2O4 pretreated under oxidizing conditions appeared higher activity compared with synthesized catalyst dealt under reductive conditions, which assign to the higher adsorption capacity of O2, as well as, the results also appeared that the catalyst showed high stability under wet and dry conditions.

Facile preparation of PtNi/Cs derived from the precipitation polymerization of a Poly(amic acid) for efficient hydrogen evolution reaction catalysis

Hydrogen evolution reaction (HER) of water is currently one of the most potential ‘green hydrogen’ production technology to alleviate the energy scarcity and environmental contamination. In this study, ultrafine platinum/nickel bimetallic nanoparticles loaded porous carbon nanocomposite, noted as PtNi/Cs, is facilely prepared by employing the precipitation polymerization of a poly (amic acid) (PAA), which shows superior catalytic performance toward HER. The synthesis of PAA is achieved via a stepwise polymerization of 4,6-diaminino-2-mercaptopyrimidine and pyromellitic dianhydride at room temperature, and the porous precursor is formed during the polymerization. Upon pyrolysis of the precursor in an inert atmosphere, carbon nanoaggregates with inherited porosity are fabricated. Ultrafine PtNi bimetallic nanoparticles with size of 3.3 ± 0.7 nm can be efficiently deposited, exhibiting an overpotential of 26.4 mV at 10 mA cm−2 and a mass activity of 2.92 A mgPt−1, superior than commercial Pt/C of 36.8 mV. The excellent HER performance can be attributed to the formation of ultrafine PtNi bimetallic nanoparticles and the electron transfer from PtNi to the nitrogen atoms on the carbon support.

Potassium Carbonate as a Low-cost and Highly Active Solid Base Catalyst for Low-Temperature Methanolysis of Polycarbonate.

Herein, potassium carbonate (K2CO3) was used as a low-cost, readily available, and highly active solid base catalyst for low-temperature PC methanolysis in the presence of THF as a solvent, producing highly pure and crystalline bisphenol A (BPA) and with a catalytic performance higher than group IIA metal oxides (MgO, CaO, and SrO) and some group IA metal carbonates (NaHCO3, KHCO3, and Na2CO3). THF was the best solvent in aiding the reaction owing to it having a similar polar parameter (δp) to that of PC according to Hansen solubility parameters. By the reaction over the catalyst, 100% PC conversion, 97% BPA yield, and 86% dimethyl carbonate yield were achieved within just 20 min at 60 °C. The catalyst possessed an apparent activation energy (Ea) of 52.3 kJ mol-1, which is the lowest value so far for heterogeneous catalysts, while the mechanistic study revealed that the reaction proceeded via the methoxide pathway. The reusability test demonstrated that the catalyst was reusable at least four times. Furthermore, this catalytic system was successfully applied to actual post-consumable PC wastes and other polyesters, including polyethylene terephthalate (PET) and polylactic acid (PLA).

Crystal facet-modulated CuO/CeO2 catalysts for highly selective catalytic reduction of NO by CO

The selective catalytic reduction of NO by CO (CO-SCR) has a significant impact on the sustainable development of the environment. It is crucial to design efficient low-temperature catalysts to overcome the challenges associated with the industrialization of CO-SCR. Herein, we present CuO/CeO2 catalysts with three different exposed crystal facets of CeO2 ((100), (110), and (111)) synthesized by a hydrothermal method followed by impregnation for CO-SCR. Among the three CuO/CeO2 catalysts, CuO loaded on rod-like CeO2 catalyst (CuO/CeO2-R) with exposed CeO2 (110) crystal facet showed the highest catalytic performance in the CO-SCR reaction, achieving complete conversion of NO and 99 % conversion of CO at 250 °C. A series of characterizations reveal that the interaction between CuO and CeO2 with different crystal facets is crucial to regulating the interface structure and oxygen vacancy (Ov) content. During in situ DRIFTS analysis, it was found that the primary adsorption sites for CO are the Cu+-Ov-Ce3+ interface sites. The CuO/CeO2-R catalyst had the highest number of these sites. Furthermore, CuO/CeO2-R contained many Ov sites, which promote NO dissociation and enhance its catalytic efficiency. This study offers insights into CO-SCR catalysis and the design of efficient catalysts by manipulating the exposed crystal facets of support to enhance CO-SCR activity.

Synergistic integration of metallic Bi and defective TiO2 for enhanced photocatalytic NO removal

The construction of hybrid catalysts is an effective method to enhance catalytic performance, but research on the positioning of the load is limited. In this study, we synthesized two photocatalytic materials by controlling the bismuth-titanium ratio and the site value of Bi modification in the catalyst. The surface-modified photocatalyst, namely 1:0.9 Bi/TiO2, exhibits a photocatalytic efficiency of 68.9% for the abatement of ppb-level NO in the presence of visible irradiation. This efficiency was significantly superior to that of the corresponding one-step synthesized Bi/TiO2 (48.7%) and the TiO2 (18.6%). Furthermore, it promotes nitrate formation and suppresses the generation of toxic NO2. Capture experiments indicate that the same active species are involved in both surface-loaded and uniformly loaded catalysts. The differences in their performance can be attributed to the higher vacancy concentration in the surface-loaded catalysts and the different local coordination environments of vacancies in the catalysts, altering the adsorption capability of oxygen molecules. This work offers fresh perspectives ffor the generation of efficient photocatalysts.

MnS doping regulating Co active sites on fibrous cobalt nitride as bifunctional oxygen electrocatalyst for high-performance Zn-air battery

Aiming to achieve high-efficiency bifunctional catalysts, doping engineering is applied to construct bifunctional catalysts for oxygen electrodes in Zn-air batteries to strengthen the catalytic kinetics of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Herein, MnS doped cobalt nitride catalyst (MnS/CoNx) with divergent fiber morphology is prepared by low temperature nitriding for the self-assembling layered double hydroxides (LDH). The MnS/CoNx shows excellent electrical conductivity and improved catalytic activity on ORR and OER with low overpotential of 290 mV at 10 mA cm−2 and a good half-wave potential of 0.80 V in ORR compared with CoNx and MnO/CoNx. The contribution of the increased bifunctional catalytic performance is possible from the more active center Co3+ and Mn4+, and the elevated electron transport resulted from the opportune high conductive MnS doping. The MnS/CoNx catalyst-driven Zn-air battery achieves a higher power density of 228 mW cm−2 and the excellent long-term stability of 500 h at 20 mA cm−2 far surpassing the commercial Pt/C+RuO2 catalyst.

Revolutionizing Tetracycline Hydrochloride Remediation: 3D Motile Light-Driven MOFs Based Micromotors in Harsh Saline Environments.

Traditional light-driven metal-organic-frameworks (MOFs)-based micromotors (MOFtors) are typically constrained to two-dimensional (2D) motion under ultraviolet or near-infrared light and often demonstrate instability and susceptibility to ions in high-saline environments. This limitation is particularly relevant to employing micromotors in water purification, as real wastewater is frequently coupled with high salinity. In response to these challenges, ultrastable MOFtors capable of three-dimensional (3D) motion under a broad spectrum of light through thermophoresis and electrophoresis are successfully synthesized. The MOFtors integrated photocatalytic porphyrin MOFs (PCN-224) with a photothermal component made of polypyrrole (PPy) by three distinct methodologies, resulting in micromotors with different motion behavior and catalytic performance. Impressively, the optimized MOFtors display exceptional maximum velocity of 1305±327µms-1 under blue light and 2357±453µms-1 under UV light. In harsh saline environments, these MOFtors are not only maintain high motility but also exhibit superior tetracycline hydrochloride (TCH) removal efficiency of 3578±510mgg-1, coupling with sulfate radical-based advanced oxidation processes and peroxymonosulfate. This research underscores the significant potential of highly efficient MOFtors with robust photocatalytic activity in effectively removing TCH in challenging saline conditions, representing a substantial advancement in applying MOFtors within real-world water treatment technologies.

Performance of cobalt doped two dimensional black phosphorus (Co-2D BP) for bifunctional hydrolysis in alkaline solution

The present study contributes to the exploration of transition metal phosphides with specific composition and structure to enhance electrocatalytic ability. Cobalt doped two dimensional black phosphorus (Co-2D BP) with layered structure exhibits excellent electrocatalytic activity for hydrogen evolution reaction (HER) in alkaline solutions, and demonstrates an overpotential of 86.42 mv at a current density of 10 mA cm−2, requiring only 140.29 mv, 198 mv, and 238.89 mv to reach 20, 50, and 100 mA cm−2 respectively. The catalytic performance was stable even after 10 h using in alkaline electrolytes, demonstrating good chemical stability. Co-2D BP can also improve the catalytic performance for oxygen evolution reaction (OER). This study provides a novel strategy for the design of multifunctional 2D BP-based catalytic materials for hydrolysis.

Manipulating Orbital Hybridization of CoSe2 by S Doping for the Highly Active Catalytic Effect of Lithium-Sulfur Batteries.

In recent years, various transition metal compounds have been extensively studied to deal with the problems of slow reaction kinetics and the shuttle effect of lithium-sulfur (Li-S) batteries. Nevertheless, their catalytic performance still needs to be further improved by enhancing intrinsic catalytic activity and enriching active sites. Doping is an effective means to boost the catalytic performance through adjusting the electron structure of the catalysts. Herein, the electron structure of CoSe2 is adjusted by doping P, S with different p electron numbers and electronegativity. After S doping (S-CoSe2), the content of Co2+ increases, and charge is redistributed. Furthermore, more electrons are transferred between Li2S4/Li2S and S-CoSe2, and optimal Co-S bonds are formed between them with optimized d-p orbital hybridization, making the bonds of Li2S4/Li2S the longest and easy to break and decompose. Consequently, the Li-S batteries with the S-CoSe2-modified separator achieve improved rate performance and cycling performance, benefiting from the better bidirectional catalytic activity. This work will provide reference for the selection of the anion doping element to enhance the catalytic effect of transition metal compounds.

Hydrolysis Mechanism of Multimodular Endoglucanases with Distinctive Domain Composition in the Saccharification of Cellulosic Substrates.

Two multimodular endoglucanases in glycoside hydrolase family 5, ReCel5 and ElCel5, share 73% identity and exhibit similar modular structures: family 1 carbohydrate-binding module (CBM1); catalytic domain; CBMX2; module of unknown function. However, they differed in their biochemical properties and catalytic performance. ReCel5 showed optimal activity at pH 4.0 and 70 °C, maintaining stability at 70 °C (>80% activity). Conversely, ElCel5 is optimal at pH 3.0 and 50 °C (>50% activity at 50 °C). ElCel5 excels in degrading CMC-Na (256 U/mg vs 53 U/mg of ReCel5). Five domain-truncated (TM1-TM5) and four domain-replaced (RM1-RM4) mutants of ReCel5 with the counterparts of ElCel5 were constructed, and their enzymatic properties were compared with those of the wild type. Only RM1, with ElCel5-CBM1, displayed enhanced thermostability and activity. The hydrolysis of pretreated corn stover was reduced in most TM and RM mutants. Molecular dynamics simulations revealed interdomain interactions within the multimodular endoglucanase, potentially affecting its structural stability and complex biological catalytic processes.