Leveraging Cu/CuFe2O4-Catalyzed Biomass-Derived Furfural Hydrodeoxygenation: A Nanoscale Metal-Organic-Framework Template Is the Prime Key

Hydrogen Production from Methanol Steam Reforming over Fe-Modified Cu/CeO2 Catalysts

Fe-modified Cu catalysts with CeO2 support, prepared by the impregnation method, were subjected to physicochemical analysis and catalytic tests in the steam reforming of methanol (SRM). Physicochemical studies of the catalysts were carried out using the XRF, TEM, STEM-EDS, XRD, TPR and nitrogen adsorption/desorption methods. XRD, TEM studies and catalytic tests of the catalysts were carried out at two reduction temperatures, 260 °C and 400 °C, to determine the relationship between the form and oxidation state of the active phase of the catalysts and the catalytic properties of these systems in the SRM. Additionally, the catalysts after the reaction were analysed for the changes in the structure and morphology using TEM methods. The presented results show that the composition of the catalysts, morphology, structure, form and oxidation state of the Cu and Fe active metals in the catalysts and the reaction temperature significantly impact their activity, selectivity and stability in the SRM process. The gradual deactivation of the studied catalysts under SRM conditions could result from the forming of carbon deposits and/or the gradual oxidation of the copper and iron phases under the reaction conditions.

Immobilizing nanozymes on 3D-printed metal substrates for enhanced peroxidase-like activity and trace-level glucose detection

The prevalence of 3D-printed portable biomedical sensing devices, which are fashioned mainly from plastic and polymer materials, introduces a pressing concern due to their limited reusability and consequential generation of substantial disposable waste. Considering this, herein, we pioneered a ground-breaking advancement, i.e., a 3D-printed metal substrate-based enzyme. Our inventive methodology involved the synthesis of a thermally degraded Fe-based metal-organic framework, DEG 500, followed by its deposition on a 3D-printed metal substrate composed of Ti-Al-V alloy. This novel composite exhibited remarkable peroxidase-like activity in a range of different temperatures and pH, coupled with the ability to detect glucose in real-world samples such as blood and fruit juices. The exceptional enzymatic behaviour was attributed to the diverse iron (Fe) oxidation states and the presence of oxygen vacancies, as evidenced through advanced characterization techniques. Fundamentally, we rigorously explored the mechanistic pathway through controlled studies and theoretical calculations, culminating in a transformative stride toward more sustainable and effective biomedical sensing practices.

Novel colorimetric detection of oxytetracycline in foods by copper nanozyme

In this study, copper nanozyme (CuNZs) possess good laccase-like activity were synthesized by grinding method with cupric chloride dihydrate as copper source, sodium borohydride as reducing agent and β-cyclodextrin as protective agent. The CuNZs can oxidize colorless 2,4-dinitrophenol (2,4-DP) to red product. When oxytetracycline (OTC) was added to the above three solutions, the color changed from red to orange and the absorbance increased again, indicating that OTC was also an affinity substrate for CuNZs. When CuNZs was mixed with OTC alone, the color changed from colorless to yellow, and the absorption intensity was related to OTC concentration. It has good selectivity and sensitivity, and had a good linear response to the concentration of OTC in the range of 50-500 μM, and the limit of detection was 0.148 μM. Thus, a fast and simple colorimetric assay for the determination of OTC was established by using the laccase-like activity of CuNZs, and it was applied successfully to detect OTC in food samples.

Synergistic contribution of metal-acid sites in selective hydrodeoxygenation of biomass derivatives over Cu/CoOx catalysts

The efficient hydrodeoxygenation (HDO) of biomass derivatives to yield specific products is a significant yet challenging task. In the present study, a Cu/CoO_x catalyst was synthesized using a facile co-precipitation method, and subsequently used for the HDO of biomass derivatives. Under optimal reaction conditions, the conversion of 5-hydroxymethylfurfural reached 100% with a selectivity of ∼99% to 2,5-diformylfuran. In combination with the experimental results, systematic characterizations revealed that CoO_x, as the acid site, tended to adsorb CO bonds, and the metal sites of Cu⁺ were inclined to adsorb CO bonds and enhance CO bond hydrogenation. Meanwhile, Cu⁰ was the main active site for 2-propanol dehydrogenation. The excellent catalytic performance could be attributed to the synergistic effects of Cu and CoO_x. Further, by optimizing the ratio of Cu to CoO_x, the Cu/CoO_x catalysts exhibited notable performance in HDO of acetophenone, levulinic acid, and furfural, which verified the universality of the catalysts in the HDO of biomass derivatives.

Aqueous phase conversion of CO2 into acetic acid over thermally transformed MIL-88B catalyst

Sustainable production of acetic acid is a high priority due to its high global manufacturing capacity and numerous applications. Currently, it is predominantly synthesized via carbonylation of methanol, in which both the reactants are fossil-derived. Carbon dioxide transformation into acetic acid is highly desirable to achieve net zero carbon emissions, but significant challenges remain to achieve this efficiently. Herein, we report a heterogeneous catalyst, thermally transformed MIL-88B with Fe⁰ and Fe₃O₄ dual active sites, for highly selective acetic acid formation via methanol hydrocarboxylation. ReaxFF molecular simulation, and X-ray characterisation results show a thermally transformed MIL-88B catalyst consisting of highly dispersed Fe⁰/Fe(II)-oxide nanoparticles in a carbonaceous matrix. This efficient catalyst showed a high acetic acid yield (590.1 mmol/g_cat.L) with 81.7% selectivity at 150 °C in the aqueous phase using LiI as a co-catalyst. Here we present a plausible reaction pathway for acetic acid formation reaction via a formic acid intermediate. No significant difference in acetic acid yield and selectivity were noticed during the catalyst recycling study up to five cycles. This work is scalable and industrially relevant for carbon dioxide utilisation to reduce carbon emissions, especially when green methanol and green hydrogen are readily available in future.

Cubic CuFe2O4 Spinel with Octahedral Fe Active Sites for Electrochemical Dechlorination of 1,2-Dichloroethane

CuFe₂O₄ spinel has been considered as a promising catalyst for the electrochemical reaction, while the nature of the crystal phase on its intrinsic activity and the kind of active site need to be further explored. Herein, the crystal phase-dependent catalytic behavior and the main active sites of CuFe₂O₄ spinel for electrochemical dechlorination of 1,2-dichloroethane are carefully studied based on the combination of experiments and theoretical calculations. Cubic and tetragonal CuFe₂O₄ are successfully prepared by a facile sol-gel method combined with high temperature calcination. Impressively, CuFe₂O₄ with the cubic phase shows a higher activity and ethylene selectivity compared to CuFe₂O₄ with the tetragonal phase, suggesting a significant facilitation of electrocatalytic performance by the cubic crystal structure. Moreover, the octahedral Fe atom on the surface of cubic CuFe₂O₄(311) is the active site responsible to produce ethylene with the energy barrier of 0.40 eV. This work demonstrates the significance of crystal phase engineering for the optimization of electrocatalytic performance and offers an efficient strategy for the development of advanced electrocatalysts.

Role of lattice strain in bifunctional catalysts for tandem furfural hydrogenation–esterification

This research represents that the bifunctional catalyst (Cu/RHSiO2–Al–Mg) which has the lowest lattice strain can significantly enhance catalytic reactivity such as the furfural conversion into furfural acetate.

Ultrahigh Metal Content Carbon-Based Catalyst for Efficient Hydrogenation of Furfural: The Regulatory Effect of Glycerol

The development of high-content non-noble metal nanocatalysts is important for multiphase catalysis applications. However, it is a challenge to solve the agglomeration in the preparation of high-content metal catalysts. In this paper, a carbon-based catalyst (Co@CN-G-600) with 71.28 wt % cobalt metal content was prepared using a new strategy of gas-phase carbon coating assisted by glycerol. The core of this strategy is to maintain the spacing of metallic cobalt by continuous replenishment of dissociated ligands during pyrolysis over gas-phase glycerol. This approach is also applicable to other non-noble metals. When Co@CN-G-600 was further used as a catalyst for the selective hydrogenation of furfural (FF) to prepare furfuryl alcohol (FOL), the yield of FOL was >99.9% under mild conditions of 80 °C, compared to only 8.23% catalytic yield at up to 130 °C for Co@CN-600 without glycerol. The excellent catalytic performance mainly lies in the fact that the introduction of glycerol modulates the size effect, electronic effect, and acidic site intensity of the high-content Co catalyst, which promotes the activation of FF and hydrogen. Meanwhile, the optimized specific surface area and pore structure by glycerol improve the accessibility of high-density active sites and promote more efficient mass transfer. In addition, the introduction of glycerol produced a graphitic carbon layer encapsulation structure relative to Co@CN-600, which substantially improved the cycling stability of the catalyst. This study resolves the paradox of high content and high dispersion of non-noble metal catalysts in the synthesis process and provides a general pathway and example for the preparation of stable high-content metal catalysts.

SO3 decomposition over silica-modified β-SiC supported CuFe2O4 catalyst: characterization, performance, and atomistic insights

The sulfur-iodine (S-I) thermochemical water-splitting cycle is one of the potential ways to produce hydrogen on a large scale. CuFe₂O₄ was dispersed over modified silica or treated β-SiC and untreated β-SiC using the wet impregnation method for SO₃ decomposition, which is the most endothermic reaction of the S-I cycle. Various state-of-the-art techniques such as XRD, FT-IR, BET, XPS, TEM, HR-TEM, FESEM-EDS and elemental mapping were employed to characterize both the synthesized catalysts. CuFe₂O₄ catalyst supported on silica-modified β-SiC resulted in enhanced catalytic activity and stability due to better metal-support interaction. In order to get a better insight into the reaction mechanism over this bimetallic catalyst, the first principles based simulation under the framework of density functional theory was performed. We have found that the presence of Cu gives rise to an improved charge localization at the O-vacancy site alongside favourable reaction kinetics, which results in an enhanced catalytic activity for the CuFe₂O₄ nano-cluster compared to that of a single metallic catalyst containing Fe₂O₃ nano-cluster.

Hydrogenation of furfural to furfuryl alcohol over MOF-derived Fe/Cu@C and Fe3O4/Cu@C catalysts

With Cu-MOF-loaded Fe(NO3)3 as the precursor (Fe(NO3)3/Cu-MOF), Fe/Cu@C and Fe3O4/Cu@C catalysts were prepared from heating under the H2 and N2 atmosphere, respectively. When Fe(NO3)3/Cu-MOF was heated under different atmospheres, Cu-MOF...

Ferrocene Derived Fe-Metalated Porous-Organic-Polymer for Core Planarity Triggered Detoxification of Chemical Warfare Agents

Here, we demonstrate successful construction of two Fe-Metalated Porous-Organic-Polymers having planar (Fe-Tt-POP) & non-planar (Fe-Rb-POP) geometry by ternary copolymerization stratergy for catalytic oxidative decontamination of different sulfur-based mustard gas simulants...

Comparing dark- and photo-Fenton-like degradation of emerging pollutant over photo-switchable Bi2WO6/CuFe2O4: Investigation on dominant reactive oxidation species

The extensive use of tetracycline hydrochloride (TCH) poses a threat to human health and the aquatic environment. Here, magnetic p-n Bi₂WO₆/CuFe₂O₄ catalyst was fabricated to efficiently remove TCH. The obtained Bi₂WO₆/CuFe₂O₄ exhibited 92.1% TCH degradation efficiency and 50.7% and 35.1% mineralization performance for TCH and raw secondary effluent from a wastewater treatment plant in a photo-Fenton-like system, respectively. The remarkable performance was attributed to the fact that photogenerated electrons accelerated the Fe(III)/Fe(II) and Cu(II)/Cu(I) conversion for the Fenton-like reaction between Fe(II)/Cu(I) and H₂O₂, thereby generating abundant •OH for pollutant oxidation. Various environmental factors including H₂O₂ concentration, initial pH, catalyst dosage, TCH concentration and inorganic ions were explored. The reactive oxidation species (ROS) quenching results and electron spin resonance (ESR) spectra confirmed that •O₂^- and •OH were responsible for the dark and photo-Fenton-like systems, respectively. The degradation mechanisms and pathways of TCH were proposed, and the toxicity of products was evaluated. This work contributes a highly efficient and environmentally friendly catalyst and provides a clear mechanistic explanation for the removal of antibiotic pollutants in environmental remediation.

Encapsulation of CuO nanoparticles within silicalite-1 as a regenerative catalyst for transfer hydrogenation of furfural

Catalytic transfer hydrogenation (CTH) of biomass-derived furfural (FAL) to furfuryl alcohol is recognized as one of the most versatile techniques for biomass valorization. However, the irreversible sintering of metal sites under the high-temperature reaction or during the coke removal regeneration process poses a serious concern. Herein, we present a silicalite-1-confined ultrasmall CuO structure (CuO@silicalite-1) and then compared its catalytic efficiency against conventional surface-supported CuO structure (CuO/silicalite-1) toward CTF of FAL with alcohols. Characterization results revealed that CuO nanoparticles encapsulated within the silicalite-1 matrix are ∼1.3 nm in size in CuO@silicalite-1, exhibiting better dispersion as compared to that in the CuO/silicalite-1. The CuO@silicalite-1, as a result, exhibited nearly 100-fold higher Cu-mass-based activity than the CuO/silicalite-1 counterpart. More importantly, the activity of the CuO@silicalite-1 catalyst can be regenerated via facile calcination to remove the surface-bound carbon deposits, unlike the CuO/silicalite-1 that suffered severe deactivation after use and cannot be effectively regenerated.

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Ultrasmall CuO NPs are encapsulated in silicalite-1 matrix for CTH of furfural

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Encapsulated CuO catalyst shows impressive Cu-mass-based activity of ∼130 hr⁻¹

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Carbon deposits can be easily removed without the obvious increase in CuO size

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Strong Cu-Si interactions exist in silicalite-1-encapsulated CuO structure

Metal-organic framework (MOF) composite materials for photocatalytic CO2 reduction under visible light

The tridentate ligand 2,4,6-tris(2-(pyridin-4-yl)vinyl)-1,3,5-triazine (TPVT) was designed and synthesized. We prepared metal-organic framework (TPVT-MOFs) crystals containing TPVT, 1,3,5-benzenetricarboxylic acid and cobalt by solvothermal reaction. Then, a series of composite materials with different contents of TPVT-MOFs were obtained by combining TPVT-MOFs with g-C3N4. Due to the interaction between TPVT-MOFs and g-C3N4, the composite materials have a more favorable valence band (VB) and conduction band (CB) for photocatalytic reduction of CO2 and oxidation of H2O. Under the conditions of visible light and a gas-solid system without a co-catalyst, a photosensitizer and a sacrificial agent, the yield of CO2 reduction by TPVT-MOFs@g-C3N4-10 can reach 56.4 μmol·g-1·h-1, which is 3.2 times that of pure g-C3N4 (17.5 μmol·g-1·h-1). The results of DFT calculations showed that the adsorption of H2O on the TPVT-MOFs@g-C3N4 composite material was more preferential, which promoted the adsorption and reduction of CO2.

Selective Hydrogenation of Furfural over the Co-Based Catalyst: A Subtle Synergy with Ni and Zn Dopants

A multimetal doping strategy has aroused extensive attention in promoting a non-noble catalyst for selective hydrogenation reaction. Herein, a multimetallic catalyst (NiCoZn@CN) with excellent catalytic performance for hydrogenation of furfural (FAL) to furfuryl alcohol (FOL) is prepared through a facile, inexpensive, and efficient pyrolysis method. Using H₂ as a H donor, extremely high selectivity (>99%) with 100% conversion is attained over the optimal NiCoZn@CN-600 catalyst. The subtle synergy between Co and Ni, Zn dopants, which remarkably promotes the performance of the Co-based catalyst, is revealed. In the NiCoZn@CN system, Co⁰ is proven to be the main active site, whose content is greatly improved by Ni and Co dopants. Additionally, the Ni dopant could also benefit activation of H₂ and the Zn dopant could enhance metal nanoparticle dispersion and the porous structure of the catalyst. In situ FTIR indicates that the vertical adsorption mode of FAL with the O_aldehyde terminal on NiCoZn@CN-600 ensures a selective hydrogenation process. With a N-doped carbon matrix, NiCoZn@CN-600 shows good cycling stability in five times run. NiCoZn@CN-600 is also competent in the catalytic transfer hydrogenation (CTH) of FOL, affording >99% yield with 2-propanol as a H donor. This study opens an avenue toward rational design of multimetallic doping catalysts with high selectivity for challenging reactions in the conversion of biomass-derived compounds.

Three-dimensional graphene encapsulated Ag-ZnFe2O4 flower-like nanocomposites with enhanced photocatalytic degradation of enrofloxacin

Three-dimensional (3D) Ag–ZnFe₂O₄-reduced graphene oxide (rGO) was successfully synthesized using a hydrothermal and photo-reduction method, and the morphological differences of the materials were observed. Their photocatalytic activity was evaluated by photocatalytic degradation of enrofloxacin (ENR) under visible-light irradiation. The results indicated that Ag–ZnFe₂O₄–rGO exhibited superior photocatalytic properties and good stability. In this research, the enhancement of photocatalytic performance is mainly attributed to the electron channelization ability of rGO, which traps the photoexcited electrons of ZnFe₂O₄ on its π framework, and reduces the electron–hole recombination rate. Moreover, the high surface area of 3D pompon mum flower-like ZnFe₂O₄ provides more reactive sites. In addition, free radical capture and ESR experiments as well as pathway analysis of degradation also confirmed that superoxide radicals (˙O₂⁻) and photo-generated holes from Ag–ZnFe₂O₄–rGO were the main active species in the degradation progress of ENR.

Three-dimensional (3D) Ag–ZnFe₂O₄-reduced graphene oxide (rGO) was successfully synthesized using a hydrothermal and photo-reduction method, and the morphological differences of the materials were observed.

An efficient environmentally friendly CuFe2O4/SiO2 catalyst for vanillyl mandelic acid oxidation in water under atmospheric pressure and a mechanism study

Aimed at the green production of vanillin, a highly efficient environmentally friendly oxidation system was introduced to oxidize VMA with a porous CuFe₂O₄/SiO₂ component nano-catalyst in aqueous solution under atmospheric pressure.

Bimetallic CuFe nanoparticles as active and stable catalysts for chemoselective hydrogenation of biomass-derived platform molecules

Chemoselective hydrogenation of 5-(hydroxymethyl)furfural (HMF) to 2,5-bis(hydroxymethyl)furan (BHMF) has been efficiently performed using bimetallic CuFe nanoparticles covered by thin carbon layers as catalysts.

Recyclable Magnetic Cu/CuFe2O4 Nanocomposites for the Rapid Degradation of 4-NP

Magnetic Cu/CuFe2O4 nanocomposites were prepared by the one-pot thermal decomposition of acetylacetone compounds. Adjusting the molar ratios of Fe to Cu was used to control the content of Cu in the synthetic process. XRD, TEM, XPS and UV-Vis were employed to reveal detailed structural and catalytic activities of Cu/CuFe2O4 nanocomposites. Magnetic measurements demonstrated that Cu/CuFe2O4 nanocomposites possessed a considerable magnetic saturation. Cu/CuFe2O4 nanocomposites showed superb efficiency in the degradation of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). 4-NP could be reduced by Cu/CuFe2O4 nanocomposites within 40 s in the attendance of NaBH4. Cu nanocrystals played an indispensable rose in the enhancement of catalytic performance. The synergistic effect of Cu and CuFe2O4 nanocrystals achieved the high-efficiency catalytic reduction for 4-NP. After six recycling experiments, the efficiency of Cu/CuFe2O4 nanocomposites was almost stable. Our work advances a straightforward strategy to synthesize efficient and recoverable Cu/CuFe2O4 nanocomposites, which has promising utilizations in the purifying of nitrophenolic contamination.

Hydrophobic Copper Catalysts Derived from Copper Phyllosilicates in the Hydrogenation of Levulinic Acid to γ-Valerolactone

A reduction-silylation-reduction method was developed to synthesize hydrophobic Cu catalysts derived from Cu phyllosilicates (CuPS). Triethoxy(octyl)silane (OTS) was used as the coupling agent. The OTS-grafted, reduced CuPS catalysts were applied in the hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL). The most promising catalyst was synthesized by reducing CuPS at a high temperature (350 °C for 3 h), followed by OTS grafting, and then by repeating the previous reduction step. High LA conversion (95.7%), GVL yield (85.2%), and stability (3 cycles with a 7.5% loss of initial activity) were obtained at a mild reaction condition (130 °C with a H₂ pressure of 12 bar). A high reduction temperature not only leads to a low oxidation state of Cu species but also suppresses the formation of silylation-induced acids. Moreover, the intrinsic activity of a reduced CuPS catalyst was nearly intact after subjecting to silylation and the second reduction treatment.

Integrated nano-architectured photocatalysts for photochemical CO2 reduction

Recent advances in nanotechnology, especially the development of integrated nanostructured materials, have offered unprecedented opportunities for photocatalytic CO2 reduction. Compared to bulk semiconductor photocatalysts, most of these nanostructured photocatalysts offer at least one advantage in areas such as photogenerated carrier kinetics, light absorption, and active surface area, supporting improved photochemical reaction efficiencies. In this review, we briefly cover the cutting-edge research activities in the area of integrated nanostructured catalysts for photochemical CO2 reduction, including aqueous and gas-phase reactions. Primarily explored are the basic principles of tailor-made nanostructured composite photocatalysts and how nanostructuring influences photochemical performance. Specifically, we summarize the recent developments related to integrated nanostructured materials for photocatalytic CO2 reduction, mainly in the following five categories: carbon-based nano-architectures, metal-organic frameworks, covalent-organic frameworks, conjugated porous polymers, and layered double hydroxide-based inorganic hybrids. Besides the technical aspects of nanostructure-enhanced catalytic performance in photochemical CO2 reduction, some future research trends and promising strategies are addressed.

Realizing Catalytic Acetophenone Hydrodeoxygenation with Palladium-Equipped Porous Organic Polymers

Porous organic polymers (POPs) constructed through covalent bonds have raised tremendous research interest because of their suitability to develop robust catalysts and their successful production with improved efficiency. In this work, we have designed and explored the properties and catalytic activity of a template-free-constructed, hydroxy (-OH) group-enriched porous organic polymer (Ph-POP) bearing functional Pd nanoparticles (Pd-NPs) by one-pot condensation of phloroglucinol (1,3,5-trihydroxybenzene) and terephthalaldehyde followed by solid-phase reduction with H₂. The encapsulated Pd-NPs rested within well-defined POP nanocages and remained undisturbed from aggregation and leaching. This polymer hybrid nanocage Pd@Ph-POP is found to enable efficient liquid-phase hydrodeoxygenation (HDO) of acetophenone (AP) with high selectivity (99%) of ethylbenzene (EB) and better activity than its Pd@Al₂O₃ counterpart. Our investigation demonstrates a facile, scalable, catalyst-template-free methodology for developing novel porous organic polymer catalysts and next-generation efficient greener chemical processes from platform molecules to produce value-added chemicals. With the aid of comprehensive in situ ATR-IR spectroscopy experiments, it is suggested that EB can be more easily desorbed in a solution, reflecting from the much weaker but better-resolved signal at 1494 cm^-1 in Pd@Ph-POP compared to that in Pd@Al₂O₃, which is the key determining factor in favoring an efficient catalytic mechanism. Density functional theory (DFT) calculations were performed to illustrate the detailed reaction network and explain the high catalytic activity observed for the fabricated Pd@Ph-POP catalyst in the HDO conversion of AP to EB. All of the hydrogenation routes, including direct hydrogenation by surface hydrogen, hydrogen transfer, and the keto-enol pathway, are evaluated, providing insights into the experimental observations. The presence of phenolic hydroxyl groups in the Ph-POP frame structure facilitates the hydrogen-shuttling mechanism for dehydration from the intermediate phenylethanol, which was identified as a crucial step for the formation of the final product ethylbenzene. Besides, weaker binding of the desired product ethylbenzene and lower coverage of surface hydrogen atoms on Pd@Ph-POP both contributed to inhibiting the overhydrogenation reaction and explained well the high yield of EB produced during the HDO conversion of AP on Pd@Ph-POP in this study.