Biomass-derived Compounds Research Articles

Designing plausible catalysts for synthesis of zingerone from vanillin and acetone via aldol condensation reaction on O-terminated M3C2-MXenes

Herein, high-performance O-terminated M3C2 MXene catalysts were screened for the synthesis of zingerone using vanillin and acetone. The electrochemical and electronic properties of O-terminated ordered MXenes in the form of M3C2O2(H) [M = Ti, V, and Cr (3d); Zr, Nb, and Mo (4d); and Hf, Ta, and W (5d)] were investigated using first principle density functional theory (DFT) calculations. These calculations revealed 37 stable candidates based on their negative binding energy values of ΔG*H and three O-terminated M3C2 MXene candidates with superior zingerone synthesis activity than pure precious metal (platinum), a UL > −0.4 V can guarantee high activity and low energy consumption during zingerone synthesis. Ti3C2O (FCC)), Hf3C2O2 (HCPFCC), and Nb3C2O2 (HCPHCP) exhibited higher catalytic activity than other candidates, and their performances were competitive for zingerone synthesis, with low limiting potentials of −0.37, −0.27, and −0.35 V, respectively. Zingerone synthesis via the protolysis reaction between vanillin and acetone includes two paths, i.e., induced protolysis and direct protolysis via the aldol condensation reaction. Multiple descriptors were used to evaluate and screen promising candidates for the synthesis of zingerone. For example, ΔG(*vanillin*acetone), and Bader charge, and d-band center analyses revealed the origin of zingerone synthesis activity based on binding energy and electronic structure. Importantly, binding energy and electronic structure have a strong intrinsic linear scaling relationship that can be used to screen for the optimal catalyst by controlling the scaling relationship between the intermediate binding energy and electronic properties. Indicating a scaling relationship and volcano plot were established based on ΔG(*vanillin+*acetone) and ΔG[*zingiberone] depending on Limiting potential (UL). Finally, we proposed a method for directly inducing protolysis during the aldol condensation reaction, which may be widely applicable to different biomass-derived carbonyl compounds, yielding chemicals and medicinal compounds through biomass valorization.

Ni-decorated carbon nanotubes (CNTs) derived from ethanol for electrooxidation of furan derivatives featuring H2 production.

This study explores advancements in concurrent biorefinery and hydrogen production using Ni-decorated CNTs derived from bioethanol as electrocatalysts, showing the complete conversion of furan derivatives to the desired products with 95-97% selectivity and a hydrogen production rate of 75 μmol h-1. These findings highlight the simultaneous upgrading of biomass-derived compounds and hydrogen production.

Rational Design of Isolated Tetrahedrally Coordinated Ti(IV) Sites in Zeolite Frameworks for Methyl Oleate Epoxidation.

The rational design of isolated metals containing zeolites is crucial for the catalytic conversion of biomass-derived compounds. Herein, we explored the insertion behavior of the isomorphic substitution of Ti(IV) in different zeolite frameworks, including ZSM-35 (FER), ZSM-5, and BEA. The different aluminium topological densities of each zeolite framework lead to the creation of different degrees of vacant sites for hosting the tetrahedrally coordinated Ti(IV) active sites. These observations show the precise control of the degree of four-coordinated Ti(IV) sites in a zeolite framework, especially in BEA topology, by tuning the degree of unoccupied sites in the host zeolite structure via dealumination. Interestingly, the more vacancies in the host zeolite structure, the more isolated tetrahedrally coordinated Ti(IV) can be increased, eventually enhancing the catalytic performance in methyl oleate (MO) epoxidation for producing methyl-9,10-epoxystearate (EP). The engineered Ti-β exhibits outstanding performances in bulky MO epoxidation with the amount of produced EP per number of Ti sites up to 17.1±1.8 mol mol-1. This observation discloses an alternative strategy for optimizing catalyst efficiency in the rational design of the Ti-embedding zeolite catalyst, endeavoring to reach highly efficient catalytic performance.

Potential cycling boosts the electrochemical conversion of polyethylene terephthalate-derived alcohol into valuable chemicals

The electrocatalytic valorization of polyethylene terephthalate-derived ethylene glycol to valuable glycolic acid offers considerable economic and environmental benefits. However, conventional methods face scalability issues due to rapid activity decay of noble metal electrocatalysts. We demonstrate that a dynamic potential cycling approach, which alternates the electrode potential between oxidizing and reducing values, significantly mitigates surface deactivation of noble metals during electrochemical oxidation of ethylene glycol. This method enhances catalyst activity by 20 times compared to a constant-potential approach, maintaining this performance for up to 60 h with minimal deactivation. In situ Raman and X-ray absorption spectroscopy show that this effectiveness results from efficient removal of surface oxide during the reaction. The strategy is applicable to polyethylene terephthalate hydrolysates and various noble metals, such as palladium, gold, and platinum, with palladium showing a high conversion rate in recent studies. Our approach offers an efficient and durable method for electrochemical upcycling of biomass-derived compounds.

Green heterogeneous catalyst based on cross-linked carrageenans for direct conversion of fructose to ethyl levulinate

Ethyl levulinate (EL) is a biomass-derived compound, capable of being converted to an array of costly compounds and therefore is attracted by many researchers. In the present study, κ and ι-carrageenan grafted methylenebisacrylamide (MBA) catalysts (κC-g-MBA and ιC-g-MBA) were prepared and applied to convert fructose to EL. FT-IR spectroscopy, XRD of both low-angle and wide-angle, N2 adsorption-and-desorption, FESEM, and TGA were used to identify the catalysts. From the catalysts, κC-g-MBA and ιC-g-MBA revealed the desirable results for EL with 80 and 82 % yields, respectively. The various parameters like reaction temperature, time, catalyst quantity, and the original fructose quantity were studied. Furthermore, experimental design was employed to create the ideal conditions for the reaction temperature 180 °C for the reaction, 5 h for the duration of the reaction, and 50 mg of catalyst for EL chosen. In addition, the catalyst's capability for reuse was explored and the catalyst was used repeatedly without a significant change in the catalyst activity.

Unlocking the potential of mixed-valence silver oxide for electrochemical valorization of 5-hydroxymethylfurfural into valuable products

The burgeoning interest in the electrocatalytic conversion of biomass-derived compounds, exemplified by 5-hydroxymethylfurfural (HMF), into economically valuable products underscores the significance of such studies. Within this context, the electrocatalytic oxidation of HMF into 2,5-diformylfuran (DFF) using the mixed-valence silver (I, III) oxide (AgO) as the catalyst is presented for the first time. A thorough investigation has been carried out to explore the complex factors influencing the electrochemical transformation of the HMF to DFF, involving applied potentials, reactant concentrations, and the significant implications of mass transfer phenomena. Under optimized conditions, DFF, one of the highest value-added intermediates, can be produced with selectivity as high as 54%. Additionally, a yield of 10.8 μmol cm−2 h−1 was obtained under mild basic condition. Another pivotal aspect of this work involves meticulously examining the reaction process, bolstered by a comprehensive analytical approach that integrates high-performance liquid chromatography (HPLC), and operando Raman spectroscopy. The amalgamation of operando Raman spectroscopy with advanced simulation techniques represents a novel endeavor, offering a groundbreaking pathway to unravel the complexities inherent in these compounds and contribute substantially to the understanding of HMF oxidation and its intermediates. By looking closely at the catalyst surface during the reaction, a valuable insight into the steps involved was developed, helping in proposing an in-depth reaction pathway.

Effects of Acid Dissociation and Ionic Solutions on the Aggregation of 2-Pyrone-4,6-dicarboxylic Acid.

The conversion of lignin can produce biomass-derived aromatic compounds such as 2-pyrone-4,6-dicarboxylic acid (PDC), which is a potential sustainable precursor of bioplastics. PDC is a pseudoaromatic dicarboxylic acid that can aggregate in aqueous solution. Aggregation depends upon PDC-PDC, PDC-water, and PDC-ion interactions that are representative of interactions in similar charged, aromatic compounds. These interactions both dictate PDC aggregation and the likelihood that PDC aggregates exhibit parallel stacking configurations that may promote PDC crystallization, which can be leveraged to separate PDC from solution. However, the interplay of interactions that drive aggregation and structure formation, and how these depend upon the charge of PDC and ionic species present in solution, remains unclear. In this work, we investigate PDC aggregation in diverse ionic solutions using all-atom molecular dynamics simulations and molecular clustering analysis. We consider ion-induced dipole interactions by using a modified Lennard-Jones nonbonded model for divalent ions in solutions. From molecular clustering analysis, we derive characteristic parameters to quantify aggregate sizes and parallel stacking configurations. We show that acid dissociation facilitates PDC aggregation in ionic solutions via ion-mediated interactions, and different ionic solutions influence both the likelihood of aggregation and the formation of parallel aggregates. In particular, we find that parallel stacking is primarily found in solutions with monovalent ions, whereas divalent ions promote larger, but less structured, aggregates. These results provide molecular-scale insight into the effects of specific ions on the aggregation of like-charged PDC molecules to inform understanding of related separation processes.

SBA-15 supported Ni-Cu catalysts for hydrodeoxygenation of m-cresol to toluene.

Amidst concerns over fossil fuel dependency and environmental sustainability, the utilization of biomass-derived aromatic compounds emerges as a viable solution across diverse industries. In this scheme, the conversion of biomass involves pyrolysis, followed by a hydrodeoxygenation (HDO) step to reduce the oxygen content of pyrolysis oils and stabilize the end products including aromatics. In this study, we explored the properties of size controlled NiCu bimetallic catalysts supported on ordered mesoporous silica (SBA-15) for the catalytic gas-phase HDO of m-cresol, a lignin model compound. We compared their performances with monometallic Ni and Cu catalysts. The prepared catalysts contained varying Ni to Cu ratios and featured an average particle size of approximately 2 nm. The catalytic tests revealed that the introduction of Cu alongside Ni enhanced the selectivity for the direct deoxygenation (DDO) pathway, yielding toluene as the primary product. Optimal performance was observed with a catalyst composition comprising 5wt.% Ni and 5wr.% Cu, achieving 85% selectivity to toluene. Further increasing the Cu content improved turnover frequency (TOF) values, but reduced DDO selectivity. These findings underscore the importance of catalyst design in facilitating biomass-derived compound transformations and offer insights into optimizing catalyst composition for more selective HDO reactions.

Chemical Transformation of Biomass-Derived Furan Compounds into Polyols

Polyols such as 1,5-pentadiol, 1,6-hexanediol, and 1,2,6-hexanetriol are crucial chemicals, traditionally derived from non-renewable fossil sources. In the pursuit of sustainable development, exploring renewable and environmentally benign routes for their production becomes imperative. Furfural and 5-hydroxymethylfurfural are C5 and C6 biomass-derived platform molecules, which have potential in the synthesis of various polyols through hydrogenation and hydrogenolysis reactions. Currently, there is an extensive body of literature exploring the transformation of biomass-derived furan compounds. However, a comprehensive review of the transformation of furan compounds to polyols is lacking. We summarized the literature from recent years about the ring-opening reaction involved in converting furan compounds to polyols. This article reviews the research progress on the transformation of furfural, furfuryl alcohol, and 2-methylfuran to 1,2-pentadiol, 1,4-pentadiol, 1,5-pentadiol, and 1,2,5-pentanetriol, as well as the transformation of 5-hydroxymethylfurfural to 1,2-hexanediol, 1,6-hexanediol, and 1,2,6-hexanetriol. The effects of the supported Pd, Pt, Ru, Ni, Cu, Co, and bimetallic catalysts are discussed through examining the synergistic effects of the catalysts and the effects of metal sites, acidic/basic sites, hydrogen spillover, etc. Reaction parameters like temperature, hydrogen pressure, and solvent are considered. The ring opening catalytic reaction of furan rings is summarized, and the catalytic mechanisms of single-metal and bimetallic catalysts and their catalytic processes and reaction conditions are discussed and summarized. It is believed that this review will act as a key reference and inspiration for researchers in this field.

Computational insights into the deoxygenation reaction of biomass-derived phenolic compounds over Ni2P (001) catalysts

This research sets the scene for understanding the interaction of phenolic molecules (i.e., phenol, o-cresol, m-cresol, and p-cresol) with Ni2P catalyst surface and how their hydrodeoxygenation reaction progresses over the surface. The hydrodeoxygenation process is responsible for removing the oxygen content from the pyrolysis oil compounds, particularly through direct deoxygenation route. Ni2P, which is one of the most common transition metal phosphides, serves as a candidate surface of this study. Two main investigations were carried out including the optimization of (1) adsorption configuration of the phenolic compounds and the (2) net charge distribution between the surface and the adsorbate. According to the adsorption energy studies, the horizontal configuration of the o-cresol molecule on the Ni2P(001) hollow site presented the most optimized and stable configuration with the least negative adsorption energy (−0.26 eV), resulting in the most negative net charge density at −0.286 |e|, as determined by the Bader charge analysis. Upon adsorption on Ni2P(001) surface, o-cresol undergoes significant charge redistribution, where the oxygen atom (-OH group) exhibits a net charge of −1.3443 |e|, indicating electron transfer to the surface. The catalytic pathway proceeded with deoxygenation followed by ring hydrogenation to produce toluene (C7H8), such that C–O bond dissociation has a reaction energy of −0.715 eV, while C–H bond formation step had a reaction energy of 0.011 eV.

Copper-Catalyzed Oxidation of 5-Hydroxymethylfurfural to 2,5-Diformylfuran Assisted by TEMPOL in Liquid Sunlight Methanol.

2,5-Diformylfuran (DFF) is a significant biomass-derived compound with diverse applications in novel furan-based materials, fragrances, fuel additives, and drug synthesis. A pivotal challenge in DFF synthesis is developing a method to produce DFF under mild conditions using sustainable feedstocks. In this study, an affordable 4-hydroxy-2,2,6,6-tetramethylpiperidine (TEMPOL)- assisted Cu(OAc)2 catalytic system for aerobic oxidation reaction of HMF to DFF in liquid sunlight methanol solvent was developed. The effects of parameters such as metal species, catalyst amount, solvent species, ligand structure, and reaction temperature were systematically investigated. The evolution of product distribution in the reaction solution at various times was monitored and analyzed using 1H-NMR spectroscopy. FT-IR and ESI-MS characterizations were employed to integrate experimental findings and elucidate the reaction mechanism. The highest DFF yield of 96% and complete conversion of HMF were obtained. Furthermore, a total DFF yield of 68.6% was achieved from fructose using a two-steps method, demonstrating the potential for scalable production. The establishment of this catalytic system presents a novel approach for the selective preparation of DFF from sustainable feedstocks.

Electrocatalytic Upgrading of Biomass-Derived Compounds for Biofuel Production

Biomass fast pyrolysis liquid (also known as bio-oil) is considered to be one of the most promising renewable carbon feedstocks. However, fresh pyrolyzed bio-oil is acidic and corrosive and contains large amounts of carbonyl and phenolic compounds produced by polymerization under acidic conditions. This work primarily utilizes an electrochemical conversion strategy using only earth-abundant metal catalysts to achieve the carbonyl hydrogenation process. The results show that upgrading this process produces biofuels with greater stability and higher specific energy. In addition to analyzing the chemical implications of this conversion strategy, this work will also discuss why electrocatalytic conversion is a promising technology path for biofuels and fine chemicals. Reference Huang, S., Lam, C. H.* et al. (2022). "The Structural Phase Effect of MoS2 in Controlling the Reaction Selectivity between Electrocatalytic Hydrogenation and Dimerization of Furfural." ACS Catalysis 12(18): 11340-11354.Huang, S., Lam, C. H.* et al. (2022). "MoS2-Catalyzed Selective Electrocatalytic Hydrogenation of Aromatic Aldehydes in an Aqueous Environment." Green Chemistry.Tu, Q., Lam, C. H.* et al. (2021). "Electrocatalysis for Chemical and Fuel Production: Investigating Climate Change Mitigation Potential and Economic Feasibility." Environmental Science & Technology 55(5): 3240-3249.Garedew, M., Lam, C. H.* et al. (2020). "Greener Routes to Biomass Waste Valorization: Lignin Transformation Through Electrocatalysis for Renewable Chemicals and Fuels Production." ChemSusChem 13(17): 4214-4237. Lam, C. H., et al. (2017). "Towards sustainable hydrocarbon fuels with biomass fast pyrolysis oil and electrocatalytic upgrading." Sustainable Energy & Fuels 1(2): 258-266. Figure 1

Microbial production of aromatic compounds and synthesis of high-performance bioplastics.

Microbial fermentation has provided fermented foods and important chemicals such as antibiotics, amino acids, and vitamins. Metabolic engineering of synthetic microbes has expanded the range of compounds produced by fermentation. Petroleum-derived aromatic compounds are widely used in industry as raw materials for pharmaceuticals, dyes, and polymers and are in great demand. This review highlights the current efforts in the microbial production of various aromatic chemicals such as aromatic amines, cinnamic acid derivatives, and flavoring aromatics, including their biosynthesis pathways. In addition, the unique biosynthetic mechanism of pyrazine, a heterocyclic compound, from amino acids is described to expand the use of biomass-derived aromatic compounds. I also discuss our efforts to develop high-performance bioplastics superior to petroleum plastics from the aromatic compounds produced by microbial fermentation.

Porous Supramolecular Crystalline Probe that Detects Non-Covalent Interactions Involved in Molecular Recognition of Furanic Compounds.

Selective separation and conversion of furan-based biomass-derived compounds, which are closely related to biorefineries, is currently an important issue. To improve their performance, it is important to deepen the understanding of non-covalent interactions that act on the molecular recognition of furanic compounds on separation or catalyst matrices. Here, a new method is reported to comprehensively visualize such intermolecular interactions using a porous supramolecular crystalline probe with polar and non-polar binding sites within a low-symmetric nanochannel consisting of four isomeric PdII 3-macrocycles. Single-crystal X-ray diffraction analysis of the crystals including 5-hydroxymethylfurfural, furfural, furfuryl alcohol, or 2-acetylfuran reveals a variety of interactions involving their furan rings and polar substituents. It is also found that cooperative and competitive effects between guest and solvent molecules significantly change their recognition mode.

Mining the Carbon Intermediates in Plastic Waste Upcycling for Constructing C-S Bond.

Postconsumer plastics are generally perceived as valueless with only a small portion of plastic waste being closed-loop recycled into similar products while most of them are discarded in landfills. Depositing plastic waste in landfills not only harms the environment but also signifies a substantial economic loss. Alternatively, constructing value-added chemical feedstocks via mining the waste-derived intermediate species as a carbon (C) source under mild electrochemical conditions is a sustainable strategy to realize the circular economy. This proof-of-concept work provides an attractive "turning trash to treasure" strategy by integrating electrocatalytic polyethylene terephthalate (PET) plastic upcycling with a chemical C-S coupling reaction to synthesize organosulfur compounds, hydroxymethanesulfonate (HMS). HMS can be produced efficiently (Faradaic efficiency, FE of ∼70%) via deliberately capturing electrophilic intermediates generated in the PET monomer (ethylene glycol, EG) upcycling process, followed by coupling them with nucleophilic sulfur (S) species (i.e., SO32- and HSO3-). Unlike many previous studies conducted under alkaline conditions, PET upcycling was performed over an amorphous MnO2 catalyst under near-neutral conditions, allowing for the stabilization of electrophilic intermediates. The compatibility of this strategy was further investigated by employing biomass-derived compounds as substrates. Moreover, comparable HMS yields can be achieved with real-world PET plastics, showing its enormous potential in practical application. Lastly, Density function theory (DFT) calculation reveals that the C-C cleavage step of EG is the rate-determining step (RDS), and amorphous MnO2 significantly decreases the energy barriers for both RDS and C-S coupling when compared to the crystalline counterpart.

Recent Progress in the Conversion of Methylfuran into Value-Added Chemicals and Fuels.

2-methylfuran is a significant organic chemical raw material which can be produced by hydrolysis, dehydration, and selective hydrogenation of biomass hemicellulose. 2-methylfuran can be converted into value-added chemicals and liquid fuels. This article reviews the latest progress in the synthesis of liquid fuel precursors through hydroxyalkylation/alkylation reactions of 2-methylfuran and biomass-derived carbonyl compounds in recent years. 2-methylfuran reacts with olefins through Diels-Alder reactions to produce chemicals, and 2-methylfuran reacts with anhydrides (or carboxylic acids) to produce acylated products. In the future application of 2-methylfuran, developing high value-added chemicals and high-density liquid fuels are two good research directions.

Atomically dispersed Zn-NxCy sites on N-doped carbon for catalytic transfer hydrogenation of ethyl levulinate into γ-valerolactone

Catalytic transfer hydrogenation (CTH) of biomass-derived carbonyl compounds provides a viable strategy to synthesize high value-added chemicals and biofuels, for which the development of efficient catalysts still remains a formidable challenge. Here, we report a Zn-based single-atom catalyst (Zn/NC-950), prepared by pyrolysis of ZIF-8 at 950 °C, for the CTH of ethyl levulinate to γ-valerolactone (GVL). This catalyst exhibited excellent performance, affording a GVL selectivity of 95.3 % at an ethyl levulinate conversion of 100 %, using isopropanol as the hydrogen source at 200 °C and autogenous pressure. The structural characterization and theoretical calculation demonstrate that such extraordinary efficacy of the Zn/NC-950 catalyst is attributed to the dual Zn-N3C1 and Zn-N2C2 sites of low Zn oxidation states, which work synergistically to generate the active hydrogen species and activate the carbonyl bonds, respectively. This work provides a rationale for the precise design of the non-noble metal single-atom catalysts efficient for the biomass valorization.

Supporting Nano Catalysts for the Selective Hydrogenation of Biomass-derived Compounds.

The selective hydrogenation of biomass derivatives presents a promising pathway for the production of high-value chemicals and fuels, thereby reducing reliance on traditional petrochemical industries. Recent strides in catalyst nanostructure engineering, achieved through tailored support properties, have significantly enhanced the hydrogenation performance in biomass upgrading. A comprehensive understanding of biomass selective upgrading reactions and the current advancement in supported catalysts is crucial for guiding future processes in renewable biomass. This review aims to summarize the development of supported nanocatalysts for the selective hydrogenation of the US DOE's biomass platform compounds derivatives into valuable upgraded molecules. The discussion includes an exploration of the reaction mechanisms and conditions in catalytic transfer hydrogenation (CTH) and high-pressure hydrogenation. By thoroughly examining the tailoring of supports, such as metal oxide catalysts and porous materials, in nano-supported catalysts, we elucidate the promoting role of nanostructure engineering in biomass hydrogenation. This endeavor seeks to establish a robust theoretical foundation for the fabrication of highly efficient catalysts. Furthermore, the review proposes prospects in the field of biomass utilization and address application bottlenecks and industrial challenges associated with the large-scale utilization of biomass.

Optimizing acidic site control for selective conversion of biomass-based sugar to furfural and levulinic acid through HSiW/MCM-41 catalyst

Furfural and levulinic acid are valuable platform compounds that can be produced by acid catalyzed conversion of sugars. Modified MCM-41 with different contents of silicotungstic acid (20 wt%-50 wt%) was successfully prepared via a wet impregnation method in order to regulate the ratio of Brønsted acid to Lewis acid. Among these catalysts, 40 wt% HSiW/MCM-41 with superior acid site density (Brønsted acid 59.35 μmol/g, Lewis acid 33.69 μmol/g) showed excellent catalytic activity as it exposed the most acidic sites and the ratio of Brønsted acid to Lewis acid reached 1.76. The conversion of biomass-based sugar was as high as 99.01 %, the maximum yield of furfural could reach 56.75 %, and the yield of levulinic acid could reach 18.88 % catalyzed by 40 wt% HSiW/MCM-41. This study provided new insights into the development of efficient and sustainable catalytic systems for the production of biomass-derived compounds.

Efficient and selective upgrading of biomass-derived furfural into 1,5 pentanediol by Co2+ etched ZIF-8 derived ZnCo layered double hydroxides nanoflake

Selective ring-opening hydrogenolysis of furfural (FF) to 1,5 pentanediol (1,5-PeD) is crucial for biomass valorization. However, achieving accurate bond-breaking is challenging. Herein, we report a facile method to synthesize layered double hydroxide nanoflake (ZnCo-LDH) mediated via Co2+ etching ZIF-8 with NaBH4 in water at ambient temperature. The structure, morphology, and chemical properties of synthesis catalysts with different concentrations of Co2+ were characterized. The results indicated a partial ZIF-8 structure in ZnCo-LDH, with increased Co2+ concentrations leading to catalyst agglomeration. Furthermore, the constitutive relationships between the catalyst’s properties and 1.5-PeD yields were established. Moreover, Co introduction altered the catalyst surface’s Brønsted and Lewis acids content. Density functional theory (DFT) indicated enhanced H2 adsorption and dissociation due to electro-transfer between Co and Zn species, with a tilted configuration favoring ring opening. Finally, a possible reaction mechanism was proposed. This work provides valuable insights for preparing ultrathin nanoflake ZnCo-LDH catalysts for biomass-derived furfur compound upgrading.