A unified view on catalytic conversion of biomass and waste plastics

Interfacial molybdate-enabled electric field deconfinement to passivate water oxidation for wide-potential biomass electrooxidation

The priority adsorption of OH- in the anodic refining process typically compromises the accessibility of organic reactants and propels their competing oxygen evolution reaction (OER), inevitably generating inactive areas of organics electrooxidation. In this work, an electric field deconfinement strategy enabled by self-originated MoO42- was unveiled to confine the mass diffusion of OH- over a Mo-modulated Ni-based electrode (NiMoOx/NF). The reconstructable NiMoOx/NF catalyst was high-efficiency for selective electrooxidation of various biomass derivatives, especially for electrocatalytic 5-hydroxymethylfurfural (HMF) oxidation reaction (e-HMFOR) to afford 2,5-furanedicarboxylic acid (FDCA, a versatile bioplastic monomer). In-situ tests and finite element analyses evidenced that NiOOH-MoO42- in-situ reconstructed from NiMoOx/NF is responsible for e-HMFOR, where the surface-adsorbed MoO42- can trigger a negative electric field to restrict OH- affinity by electrostatic repulsion but facilitate HMF adsorption, thereby leading to the deteriorated OER and enhanced e-HMFOR. Theoretical calculations further elaborated that introduced MoO42- boosts HMF adsorption to accelerate the reaction kinetics but elevates the energy barrier of O* coupling into OOH* to passivate OER. As a result, a wide potential interval (1.35-1.55 VRHE) was applicable to produce FDCA via e-HMFOR with admirable productivity (95.4-97.8% faradaic efficiencies), rivaling the state-of-the-art Ni-based electrodes. In addition, the established membrane electrode assembly electrolyzer could be operated stably for 40 h at least, with high efficiency in electrosynthesis of gram-grade FDCA. This study underlines the viability and criticality of electric field deconfinement for manipulating the OH- adsorption to facilitate organics electrooxidation and biorefinery while getting rid of competing reactions.

Atomic Scale Engineering of Multivalence-State Palladium Photocatalyst for Transfer Hydrogenation with Water as a Proton Source

Hydrogenation reactions are fundamental in the fine chemical, pharmaceutical, and petrochemical industries, however heavily relying on H2 gas at high temperatures and pressures, incurring large energy and carbon costs. Photocatalytic transfer hydrogenation, using water as a proton source, offers a greener alternative, but existing photocatalysts often suffer from modest yields, limited selectivity, and narrow substrate scope. Additionally, they often require co-activation, such as Mg-activated water or non-sustainable hydrogen feeds. Here, a photocatalyst is introduced that offers high yields and selectivities across a broad spectrum of organic compounds. The developed photocatalyst is a multivalence palladium superstructure with ultrasmall Pd0 nanoparticles enveloped by isolated Pd2+/Pd4+ atoms within a carbon-nitride matrix. Mechanistic studies reveal that the redox-flexible Pd single atoms, with triethylamine as an electronic modulator, attract photogenerated holes for water oxidation, while Pd0 nanoparticles facilitate hydrogen transfer to the unsaturated bonds of the organic molecules. The cooperative and dynamic behavior of Pd centers during catalysis, involving transitions among Pd+2, Pd+3, and Pd+4 states, is validated using operando electron paramagnetic resonance spectroscopy. This multivalent palladium catalyst represents a conceptual advance in photocatalytic transfer hydrogenation with water as a hydrogen source, holding promise for sustainable hydrogenation processes in the chemical industry.

Electrooxidation of Ethylene Glycol to Glycolic Acid with Pt-Ni(OH)2 Catalysts: High Efficiency and Selectivity for PET Plastics Upgrading

The electroconversion of polyethylene terephthalate (PET) into C2 fine chemicals and hydrogen (H2) presents a promising solution for advancing the circular plastics economy. In this study, we report the electrooxidation of ethylene glycol (EG) to glycolic acid (GA) using a Pt-Ni(OH)2 catalyst, achieving a high Faraday efficiency (>90 %) even at high current densities (250 mA cm-2 at 0.8 V vs. RHE). Notably, this catalyst outperforms most existing Pt-based catalysts in terms of catalytic activity. Experimental analyses reveal that: 1) Ni(OH)2 enhances the adsorption of OH- ions and promotes the rapid generation of *OH active species, which are essential for the efficient oxidation of EG to GA; 2) the oxygenophilic nature of Pt improves EG adsorption, and in synergy with Ni, accelerates the oxidation process. Furthermore, Pt lowers the electrolysis potential, preventing excessive oxidation and ensuring high selectivity for GA. This work offers a promising pathway for the electrooxidation-based upgrading of PET plastics and provides valuable insights for future research in this area.

Singlet-Oxygen-Driven Cooperative Photocatalytic Coupling of Biomass Valorization and Hydrogen Peroxide Production Using Covalent Organic Frameworks

Traditional H2O2 photocatalysis primarily depends on photoexcited electrons and holes to drive oxygen reduction and water oxidation, respectively. However, singlet oxygen (1O2), often underappreciated, plays a pivotal role in H2O2 production. Meanwhile, photocatalytic biomass conversion has attracted attention, yet studies combining H2O2 synthesis with biomass valorization remain rare and typically yield low-value products. Herein, a strategy of photocatalytic valorization of furfuryl alcohol (FFA) coupled with the efficient co-production of H2O2 is reported, enabled by covalent organic frameworks (COFs) induced, 1O2-participated Achmatowicz rearrangement. This study introduces polyimide-based COF-N0-3 with tailored nitrogen content, representing an unprecedently efficient platform for 1O2 production. Remarkably, reducing the nitrogen content of the COF enhances 1O2 production, significantly boosting the H2O2 generation rate. In FFA, the primary pathway for H2O2 production is Achmatowicz rearrangement, achieving a rate ten times higher than that reliant on oxygen reduction reaction in pure water, reaching 4549 µmol g⁻¹ h⁻¹. Mechanism studies revealed 1O2 selectively engaged FFA, bypassing hole oxidation to trigger the Achmatowicz rearrangement, producing valuable 6-hydroxy-(2H)-pyranone with 99% conversion and 92% selectivity. This work establishes a coupling strategy for simultaneous synthesis of H2O2 and biochemicals, offering a transformative approach to sustainable photocatalysis.

Activating Molybdenum Peroxide Scissors for Converting Polyamide Plastic into Low Carbon Alcohols

Direct chemical conversion of plastic waste into low-carbon oxygenates, rather than carbon dioxide, with renewable energy, is important yet challenging. Due to high C─X (X═C, H, N) bond energy, fully optimized catalysts are required to enable precise bond cleavage for boosted efficiency and selectivity. Here, adaptable and recyclable molybdenum peroxide photocatalysts that demonstrate chemical scissors for the selective conversion of polyamide to alcohols are reported. It shows that dimensionally adaptable Mo(+5.8)-(O2) is activated via a ligand-to-metal charge transfer (LMCT) process for localized catalysis to precisely cleave C─X bonds into C2 and C1 alcohols. The additional hydrogen peroxide facilitates the activation and regeneration of the catalytic scissors. These scissors ultimately cut PA6 into methanol with an efficiency of 2.55 mmol L-1 h-1 and a selectivity of 82.4 %. This work provides insights into the role of adaptable metal peroxides in precisely cutting C─X bonds, which benefits chemical conversion of plastic wastes.

Deciphering the Role of Second Metal in M-Ni (M = Fe, Ni, and Mn) Heterobimetallic Electrocatalysts in Controlling the HAT versus Hydride Transfer Mechanism for the Dehydrogenation of Alcohols

The second 3d-transition metal incorporation in Ni-(oxy)hydroxide has a drastic effect on alkaline OER and alcohol dehydrogenation reactivity. While Mn incorporation suppresses the alkaline OER, it greatly improves the alcohol dehydrogenation reactivity. A complete reversal of reactivity is obtained when Fe is incorporated, which shows better performance for alkaline OER with poor alcohol dehydrogenation reactivity. The role of the second 3d-metal is elusive due to the lack of systematic mechanistic studies. In this report, we thoroughly analyzed a series of M─Ni (M = Fe, Ni, Mn) (oxy)hydroxides derived from electrochemical activation of M-MOF grown on nickel foam for its electrochemical activity in alkaline OER and aliphatic, benzyl alcohol dehydrogenation. With the help of pH-dependence and kinetic isotope effect studies, the potential-determining step (PDS) and the rate-determining step (RDS) have been elucidated. The Hammett analysis revealed critical information about the transition state and offered insight into the hydrogen atom transfer (HAT) versus hydride transfer (HT) for alcohol dehydrogenation operative in various heterobimetallic electrocatalysts. Further, the superior alcohol dehydrogenation reactivity of NiMn catalyst for PET hydrolysate electro-oxidation is extended to afford valuable chemicals with concomitant production of hydrogen.

Cost-Effective and Low-Carbon Scalable Recycling of Waste Polyethylene Terephthalate Through Bio-Based Guaiacol-Enhanced Methanolysis

The global plastic waste crisis, particularly from polyethylene terephthalate (PET), demands sustainable recycling solutions. PET methanolysis offers a promising route to recover high-purity dimethyl terephthalate (DMT), but achieving scalable, cost-effective, and environmentally friendly processes under mild conditions remains challenging. This study introduces a bio-based catalytic system using guaiacol and potassium bicarbonate (KHCO3) under mild conditions (120 °C, 0.6 MPa), achieving 94% DMT and 98% ethylene glycol (EG) yields within 2 h. Unlike conventional acid-catalyzed or co-solvent-assisted methanolysis methods, the phenolic hydroxyl group of guaiacol critically stabilizes the tetrahedral intermediate, significantly enhancing catalytic efficiency. The system demonstrates broad versatility across various polyesters and real-world PET waste streams, including mixed textiles and colored plastics, while enabling selective depolymerization. Life cycle assessment (LCA) and techno-economic analysis (TEA) confirm its low carbon footprint, energy efficiency, and industrial viability. This cost-effective and scalable strategy offers a sustainable solution for PET recycling, addressing both environmental and economic challenges while advancing resource circularity in the plastic industry.

Hydrogen Spillover-Induced Brønsted Acidity Enables Controllable Hydrocracking of Polyolefin Waste to Liquid Fuels

Efficient upcycling of polyolefin waste into liquid fuels remains challenging due to over-cracking and the lack of sufficient acidity in non-zeolitic catalysts. Here, we report a Ni/niobium oxide nanorod (Ni/NbOx) catalyst that achieves 95% selectivity to C5-20​ alkanes at full polyethylene (PE) conversion under mild conditions (240 °C), with minimal gaseous products (4%). The catalyst reaches a high liquid fuel formation rate of 1274 gliquid​ gNi -1​ h-1, rivaling noble metal systems. Its performance is governed by the morphology and crystallinity of NbOx nanorods, which provide sufficient acidity without micropore confinement, mitigating diffusion limitations and over-cracking. Detailed operando infrared spectroscopy and computational studies reveal, for the first time, that Brønsted acid sites, generated in situ via hydrogen spillover on the (110) facet, are the key catalytic sites in niobium oxide-based catalysts. The density of these acid sites exhibits a linear correlation with hydrocracking activity. The catalyst also demonstrates high efficiency across diverse polyolefin feedstocks and excellent reusability, offering a scalable and cost-effective solution for plastic upcycling.

Selective hydrogenation of HMF to DHMF with Ru-PNP complexes in ionic liquids

The catalytic hydrogenation of 5-hydroxymethylfurfural (HMF) to 2,5-dihydroxymethylfuran (DHMF) represents a promising pathway for the valorisation of lignocellulosic-derived biomass feedstock. This study investigates the use of Ru-PNP complexes as (pre)catalysts to achieve efficient and highly selective hydrogenation of HMF in ionic liquids (ILs) as green reaction media under mild reaction conditions. Our results indicate that iPrRu-MACHO leads to excellent conversion and yield (up to 99%) of HMF to DHMF using 1-butyl-3-methylimidazolium acetate (BMIM OAc). The analogous cationic Ru-PNP complex bearing acetonitrile as ancillary ligand and hexafluorophosphate (PF6 -) as counterion also shows high catalytic activity (up to 99% conversion) in BMIM OAc under mild reaction conditions. Interestingly, the IL seems to prevent HMF polymerization to humins. Furthermore, the recyclability and reusability of the ionic liquid are systematically investigated.

Synergistic Co-Recycling: Selective Oxidation of Polyethylene to Dicarboxylic Acids over Spent LiCoO2 Cathodes

The escalating production of lithium-ion batteries and plastics poses critical challenges to environmental integrity and resource sustainability. Here, we report a synergistic co-recycling strategy for spent lithium cobalt oxide (LCO) cathodes and waste polyethylene (PE), leveraging the catalytic properties of LCO to oxidize PE into high-value dicarboxylic acids. Through a combination of density functional theory calculations, electron spin resonance, and in situ infrared spectroscopy, we reveal that lithium-deficient LCO undergoes a spin-state transition of Co3+ to a high-spin state, facilitating the activation of oxygen and the generation of singlet oxygen. This reactive oxygen species drives the selective oxidation of PE via hydrogen atom transfer, achieving dicarboxylic acid yields of up to 77.5 wt%, markedly exceeding previous benchmarks. Validation with real-world plastic waste and spent batteries underscores the feasibility of this approach, presenting a sustainable paradigm-shift solution for the efficient management of lithium-ion batteries and plastic waste in a circular economy.

Stable Ni(II) sites in Prussian blue analogue for selective, ampere-level ethylene glycol electrooxidation

The industrial implementation of coupled electrochemical hydrogen production systems necessitates high power density and high product selectivity for economic viability and safety. However, for organic nucleophiles (e.g., methanol, urea, and amine) electrooxidation in the anode, most catalytic materials undergo unavoidable reconstruction to generate high-valent metal sites under harsh operation conditions, resulting in competition with oxygen evolution reaction. Here, we present unique Ni(II) sites in Prussian blue analogue (NiFe-sc-PBA) that serve as stable, efficient and selective active sites for ethylene glycol (EG) electrooxidation to formic acid, particularly at ampere-level current densities. Our in situ/operando characterizations demonstrate the robustness of Ni(II) sites during EG electrooxidation. Molecular dynamics simulations further illustrate that EG molecule tends to accumulate on the NiFe-sc-PBA surface, preventing hydroxyl-induced reconstruction in alkaline solutions. The stable Ni(II) sites in NiFe-sc-PBA anodes exhibit efficient and selective EG electrooxidation performance in a coupled electrochemical hydrogen production flow cell, producing high-value formic acid compared to traditional alkaline water splitting. The coupled system can continuously operate at stepwise ampere-level current densities (switchable 1.0 or 1.5 A cm-2) for over 500 hours without performance degradation.

Selective Degradation of Polyethylene Terephthalate Plastic Waste Using Iron Salt Photocatalysts

Plastic pollution poses a significant challenge to environmental conservation. Efficient recycling of plastic is a key strategy to address this issue. Polyethylene terephthalate (PET), commonly found in plastic bottles, represents a substantial portion of plastic waste. Consequently, the efficient degradation and recycling of PET is crucial for the sustainable development of society. However, the implementation of methods for PET depolymerization and recycling typically necessitates alkaline/acidic pre-treatment and significant energy input for heating. Here, we propose a gentle, and highly efficient photocatalysis approach for selectively degrading PET plastic waste into terephthalic acid (TPA) in high yield (up to 99 %) using cost-effective iron salts. Notably, this method achieved excellent selectivity with high TON and TOF values, applying oxygen or air as environmentally friendly oxidants. In addition, the solvent can be recycled without compromising the TPA yield, and large-scale reactions can be performed smoothly.

Microwave-assisted Lewis acid catalysis for one-step preparation of high-performance buckwheat peptide-based films: Efficacy, mechanism, and applications

This study presents a novel method for the efficient preparation of peptide-based films through microwave-assisted Lewis acid catalysis (MALC) of buckwheat globulin (BG). The MALC process efficiently degraded BG into small molecular peptides (1.6-1.8 kDa) within 10 min. These peptides formed aggregates with a high β-sheet content through coordination with metal ions, which demonstrated a strong ability to create highly cross-linked network structures. The peptide-based films (PFs), without the addition of any cross-linking agents, exhibited excellent tensile strength (1.65-3.62 MPa), elongation at break (11.52-44.61 %), superior oxygen barrier properties (0.06-2.45 cm3/m2·day), and low swelling rates (20-36 %). Notably, the PFs also possessed strong antibacterial, antioxidant, and ultraviolet resistance capabilities, extending the shelf life of fresh chili peppers by approximately 7 days. This study enhances our understanding of the interactions between transition metal ions and plant proteins, establishing a technological foundation for the large-scale application of plant protein films.

Efficient bio-oxidation of biomass-derived furan-2,5-dicarbaldehyde to 5-formyl-2-furoic acid and 2,5-furandicarboxylic acid via whole-cell biocatalysis

The production of bio-based fine chemicals is increasingly important to address fossil energy shortages, climate change, and other environmental issues. Using abundant and renewable bioresource as starting material to manufacture bio-based fine chemicals will achieve a green circular economy. 5-Formyl-2-furoic acid (FFCA) and 2,5-furandicarboxylic acid (FDCA) have broad application prospects in fuels, chemical intermediates, polymers and pharmaceuticals. In this research, a green and effectual biotransformation process was built to manufacture FFCA and FDCA from biomass-derived furan-2,5-dicarbaldehyde (DFF) in DMSO-H2O using recombinant Escherichia coli cells carrying AAOase (aryl-alcohol oxidase) as biocatalyst. Under mild performance conditions, FFCA could be produced from 75 mM DFF in a high yield (92.3 %) within 24 h. 25 mM DFF was fully oxidized to FDCA within 24 h. The research established an effectual biocatalytic system for transforming HMF-derived DFF with AAOase biocatalysts into valuable biomass-derived products. This study holds great promising for sustainably synthesizing FFCA and FDCA.

Polyolefin Recycling with Binary Cobalt-Nickel Nanosheets

The recycling of polyolefin plastics into value-added chemicals has emerged as a new frontier regarding the current environmental concerns. In this work, it is demonstrated that binary cobalt-nickel nanosheets (Co─Ni NSs) can serve as a non-noble catalyst for recycling polyethylene and polypropylene plastics. Detailed analysis implies that the strong synergy between Co and Ni in binary Co─Ni NSs enables the electron transfer from Ni to Co and enhances adsorption abilities to H2 and C─C chain, realizing the cracking of polyethylene plastic to liquid products with a selectivity of 83.3% at a conversion of >98%. Impressively, such a catalyst can realize the successful recycling of commercial polyolefin wastes into value-added products. Given the enhanced stability, high selectivity to liquid products, and low-cost of Co─Ni NSs, this work provides a feasible strategy for recycling polyolefin plastics, which will attract extensive attention in various fields including catalysis, materials, energy, and beyond.

Selective Asymmetric Hydrogenation of Waste Polyethylene Terephthalate via Controlled Sorption through Precisely Tuned Moderate Acid Sites

The partial hydrogenation of waste polyethylene terephthalate (PET) offers a great opportunity to produce valuable chemicals, yet achieving precise catalytic control remains challenging. Herein, for the first time, we realized one-pot selective hydrogenation of waste PET to p-toluic acid (p-TA) with a record-high yield of 53.4%, alongside a 36.4% yield of p-xylene (PX), using a specially designed PtW/MCM-48 catalyst. Mechanistic investigations revealed that the exceptional catalytic performance arises from synergistic interaction between Pt nanoparticles and WOx species. Low-valent WOx enhances Pt dispersion, while Pt stabilizes WOx as low-polymerized polytungstates. The moderate acidity of PtW1.5/MCM-48 ensures controlled desorption of p-TA, preventing overhydrogenation to PX. The catalyst demonstrated robust performance with real-world PET waste. Life cycle assessment and technical and economic evaluation further highlight its practical feasibility. This study establishes a sustainable pathway for PET chemical upcycling and provides a framework for designing advanced catalysts for selective hydrogenation reactions, addressing critical challenges in circular chemistry and plastic waste management.

Understanding Biomass Valorization through Electrocatalysis: Transformation of Glycerol and Furan Derivatives

Electrochemical conversion of underutilized biomass provides a green approach for their valorization into high-value-added products, which constitutes a mild, safe, and green procedure. Moreover, the use of an electrochemical pathway in contrast to the classical routes (thermo or biochemical) offers several advantages in terms of product selectivity, safety, catalyst stability, and reusability. The highly variable number of tunable conditions in an electrochemical reaction offers a broad space for improvement until the optimum ones are achieved, including substrates, curent and voltage, electrodes, electrolytes, and cell set-up. The present Perspective aims to provide an informative overview into the biomass and waste valorization of furan derivatives and byproducts of biofuel refineries (glycerol) by reviewing the essential aspects of this field. We cover the fundamentals of electrochemical organic transformations, emphasizing the different parameters to consider during these procedures. We highlight the potential of electrochemical methods for biomass valorization and suggest new directions for more sustainable research.

Photothermocatalytic Wet Reforming of Waste Plastics to Syngas

The increasing accumulation of plastic waste in the environment poses a serious threat to the ecosystem and health sector, urging us to develop sustainable strategies to tackle this issue. Converting plastic waste into platform chemicals using sustainable energy and primary resources can mitigate environmental pollution and reduce CO2 emissions. In this study, polyolefins were transformed into syngas through a wet reforming process over a nickel-supported oxygen vacancy-rich titanium dioxide (Ni/TiO2-x) catalyst with water as the reactant under light irradiation. The focused light irradiation can readily increase the temperature in the reactor for the dehydrogenation and degradation of polyethylene (PE) to occur, followed by the wet reforming of PE-derived compounds and gaseous hydrocarbons to syngas. Additionally, the transfer of electrons from TiO2-x to the nickel components under light irradiation facilitates the aforementioned reactions. The current work presents a sustainable strategy for valorization of plastic waste to syngas, serving as a platform feedstock for the subsequent production of various chemicals.

Upcycling waste commodity polymers into high-performance polyarylate materials with direct utilization of capping agent impurities

Commodity polymers are ubiquitous in our society, having replaced many inorganic and metal-based materials due to their versatile properties. However, their functionality heavily relies on the addition of various components known as additives, making it challenging to recycle the polymer fraction of plastic materials effectively. Thus, it is crucial to develop efficient chemical recovery strategies for commodity polymers and additives to facilitate the direct utilization of recovered monomers and additives without additional purification. Here, we develop a strategy for co-upcycling two types of waste commodity polymers, polycarbonate, and polyethylene terephthalate into polyarylate, a high-performance transparent engineering plastic. By incorporating a highly active metal-free ionic liquids catalyst for methanolysis and a two-stage interface polymerization technique with variable temperature control, we successfully prepare polyacrylate film materials from real end-of-life plastics with direct utilization of capping agent impurities in recovered monomers. These materials exhibit excellent thermal performance (Tg = 192.8 °C), transmittance (reach up to 86.73%), and flame-retardant properties (V-0, UL-94), equivalent to those of commercial polyarylate (U-100, about $10000/ton), and could be further easily close-loop recycled. Demonstrated in kilogram-scale experiments and life cycle assessments, this approach offers a low-carbon, environmentally friendly, and economically feasible pathway for upcycling waste commodity polymers.

Accessing a Carboxyl-Anhydride Molecular Switch-Mediated Recyclable PECT Through Upcycling End-of-Use PET

Poly(ethylene terephthalate) (PET), with an annual production of exceeding 70 million tons, is mainly utilized in disposable fields and subsequently contribute to severe environmental pollution. Conventional chemical recycling, which typically involves depolymerizing polymer into monomers, is limited due to the intricate recycling process, excess using unrecyclable solvents and low polymer conversion. Inspired by protein's molecular switches, we propose a novel polymer-to-polymer recycling strategy based on polycondensation principles upcycling waste PET to high-value recyclable poly(ethylene-co-1,4-cyclohexanedimethanol terephthalate) derivatives containing molecular switches. Upon deactivating the molecular switch, an acidification reaction occurs within the system, leading to a rapid and controllable reduction in molecular weight due to the imbalance of reactive group. Conversely, activating the molecular switch triggers a ring-closing reaction that detaches acid anhydrides, bringing about equal molar ratio of groups and thereby facilitating an increase in molecular weight. By simply incorporating a molecular switch into condensation products based on melt polycondensation, closed-loop recycling capability is achieved without necessitating excessive organic solvents or complex depolymerization processes. The present study not only presents a novel pathway for end-of-use PET upcycling but also introduces an innovative concept of molecular switching for the closed-loop recyclability of condensation polymers, thereby demonstrating significant potential for large-scale implementation.

Catalysis Enhanced by Catalyst Wettability

Heterogeneous catalysis is a surface phenomenon where the adsorption, desorption, and transfer of reactants and products are critical for catalytic performance. Recent results show that catalyst wettability is strongly related to the adsorption, desorption, and transfer of reactants and products. In this review, we briefly summarize strategies for regulating wettability to enrich reactants, accelerate the desorption of products, and promote mass transfer in heterogeneous catalysis. In addition, we explore insights into catalyst wettability for the enhancement of catalytic performance. Finally, the concerns and challenges in this subject are outlined, and practical strategies are proposed for the regulation of catalyst wettability. We hope that this review will be helpful for designing highly efficient heterogeneous catalysts in the future.

Natural-selected plastics biodegradation species and enzymes in landfills

Biodegradation is a promising and environmentally friendly strategy for plastic pollution management. Landfills decompose municipal solid waste, including almost 50% of global plastic debris and even some of the oldest synthetic plastics, fostering naturally selected plastic biodegradation. Herein, we present a global collection of plastic biocatalytic enzymes from landfills using metagenomics and machine learning. Metagenomic analysis identified 117 plastic-degrading genes, with 39 incorporated in 22 prokaryotic metagenome-assembled genomes (MAGs). A machine-learning approach predicted 978,107 candidate plastic-degrading genes, 712 of which were encoded respectively by 150 MAGs. Our results highlight landfills as reservoirs of diverse, naturally selected plastic-degrading microbes and enzymes, serving as references and/or models for biocatalysis engineering and in situ bioremediation of plastic pollution.

Atomic Hydrogen in Hydrogenolysis: Converting and Detoxifying Carbon-Heteroatom Bonds via Paired Electrolysis

The presence of carbon-heteroatom bonds (C-N, C-O, and C-S) significantly enhances the stability and toxicity of pollutants. Hydroxyl radicals (•OH)-mediated electrochemical processes show promise; however, the bond energies associated with carbon-heteroatom bonds exceed 200 kJ/mol, which constrains the effectiveness of oxidative degradation and detoxification. We have developed a paired electrolysis process coupling hydrogen atom (H*) generation at the cathode with •OH production at the anode. The involvement of H* and •OH in this system was first confirmed by using methylene blue (MB) as an electrochemical probe. When applied to the degradation of glyphosate (GP), which contains C-N bonds, the paired electrolysis process achieved removal efficiencies for COD, TOC, and toxicity that were twice those of individual oxidation processes. The degradation kinetics also exhibited performance that was double that of individual oxidation processes. Mass spectrometry and theoretical calculations confirmed that hydrogenolysis of H* effectively attacks high-energy C-N bonds, thereby circumventing the rate-limiting steps associated with standalone •OH oxidation, enhancing pollutant degradation and reducing toxicity. When applied to pollutants containing C-O and C-S bonds, the paired electrolysis process demonstrated improvements in COD, TOC, and toxicity removal of approximately 30%, 10%, and 20%, respectively, showcasing its multifunctionality and scalability. Seven days of practical wastewater experiments further validated the effectiveness and durability of this technology.

New insights into cyclopropanation: application in the synthesis of a novel high-heating-value hydrocarbon fuel derived from furfural

Cyclopropanation is crucial in synthesizing high-heating-value fuels. In situ experiments and computational studies provide new insights into the four-step cyclopropanation, where the high activity of Al carbenoid is attributed to the electron shift from olefin to Al carbenoid and high proximity of Al carbenoid with olefin.

Highly selective upcycling of plastic mixture waste by microwave-assisted catalysis over Zn/b-ZnO

7 billion of 9.2 billion tons of plastic produced becomes waste while conventional catalytic plastic recycling methods are vulnerable with degraded performance and intensive energy input. Here, a hybrid Zn/b-ZnO catalyst, together with the specially-designed microwave reaction system, has achieved fast plastic waste upgrading under atmospheric pressure without using H2. Bifunctional ZnO acts as a microwave absorber and substrate catalyst, and in-situ formed Zn clusters promote C-C bond cleavage and nearly 100% upcycle landfilled plastic mixtures into lubricant base oil precursors and monomers. Unprecedented turnover number (250 gplastic g-1catalyst) of plastic depolymerisation and long-time stability over 50 successive cycles have been demonstrated, together with 8-time higher energy efficiency compared with conventional catalysis, indicating this strategy is an economical approach to efficient upcycling of plastics towards valuable products. Moreover, the catalyst can tolerate high contaminates, even the landfilled plastics can still be converted to lubricant base oil precursors, which has never been reported before.

Bimetallic synergy in supported Ni-Pd catalyst for selective hydrogenolysis of C-O bonds in epoxy resins

Recycling of epoxy composites is of importance for achieving circular economy as demand for lightweight materials in the field of sustainable technologies is soaring. Although catalytic hydrogenolysis of epoxy resins provides a promising approach to recover valuable fillers and phenolic compounds from the composites, there is a lack of a reusable solid catalyst for this purpose. Here, we report a robust CeO2-supported Ni-Pd bimetallic catalyst (Ni-Pd/CeO2) for the hydrogenolysis of C-O bonds in epoxy resins under 1 atm of H2. Benefiting from its heterogeneous nature, Ni-Pd/CeO2 can be reused for several times. Furthermore, the catalyst is successfully applied to decomposition of epoxy composites to recover carbon or glass fibers and phenolic compounds, implying the potential application of our catalyst system toward recycling of epoxy composites.

Regulating Carbon Vacancies and Undercoordinated Mo Sites in Mo2C Catalysts Toward Photo-Thermal Catalytic Conversion of Biomass Into H2 Fuel

The conversion of biomass into chemical fuels is exciting but quite challenging in the development of an effective conversion strategy to generate easily-separated products without energy consumption. Herein, a lignocellulosic biomass-to-H2 conversion system via photo-thermal catalysis over Mo2C hierarchical nanotube catalysts in an acidic solution, in which the lignocellulose is hydrolyzed to small organic molecules (such as glucose, etc) by dilute H2SO4, and then the resulting glucose is oxidized by Mo2C catalyst to generate H2 are reported. During the photo-thermal catalytic processes, the carbon vacancy in Mo2C catalysts results in the generation of undercoordinated Mo sites, which act as active sites for both biomass oxidation and H2 generation reactions. Thus, the successful photo-thermal catalytic conversion of common agricultural and forestry biomass including polar wood chip, bamboo, wheat straw, rice straw, corncob, and rice hull into H2 fuel is realized, and the highest H2 generation rate achieves 30 µmol g-1 h-1 in the wheat straw system. Outwork affords efficient noble-metal-free catalysts with adjustable active sites for photo-thermal catalytic conversion of lignocellulosic biomass into H2.

Microwave-Powered Liquid Metal Degradation of Polyolefins

Upcycling waste plastics is highly promising to tackle global white pollution while achieving sustainable development. However, prevailing approaches often encounter challenges in scalable engineering practices due to either insufficient plastic upcycling capability or arduousness in the separation, recovery, and purification of catalysts, which inevitably augments the cost of plastic upcycling. Here, the microwave-powered liquid metal synergetic depolymerization is presented to facilitate low-cost plastic upcycling. By leveraging the fluidity of liquid metals and their exceptional chemical-bond activation ability under microwave field, this method efficiently converts various polyolefins into narrowband hydrocarbon oil (Oil yield: 81 wt.% for polypropylene (PP), 85.9 wt.% for polyethylene (PE)) and high-value olefin monomers (C2-4  selectivity: 50% for PE, 65.3% for PP) over 30 successive cycles, resulting in a high turnover frequency of 2.83 kgPlastic mLLiquid metal -1. These captivating advantages offered by electromagnetically-powered liquid metals are also supported by their self-separation features, thereby paving the way for large-scale engineering solutions in waste plastic upcycling.

Balancing Competitive Adsorption on Co3O4@P, N-Doped Porous Carbon to Enhance the Electrocatalytic Upgrading of Biomass Derivatives

The electrocatalytic oxidation of 5-hydroxymethylfurfural (HMF) represents an environmentally friendly approach to generate high-value-added chemicals from biomass. The successful electrochemical transformation of HMF during the oxidation reaction (HMFOR) necessitates an ideal adsorption interaction between HMF and OH- on the electrode surface. Yet, catalysts with a singular active site offer limited flexibility in managing the competitive adsorption of HMF and OH-. To this end, different active sites are customized in this work to construct a P and N co-doped porous carbon that wrapped Co3O4 (Co3O4@PNC). Co-doping with these two heteroatoms generates C3P = O and pyrrolic N as adsorption sites to better balance the adsorption of HMF and OH-, respectively, rather than promoting competition between the HMF and OH- on a single active site. With this design strategy, Co3O4@PNC demonstrates significant HMFOR activity, the conversion rate of HMF surpassed 99% with a 2,5-furandicarboxylic acid (FDCA) yield exceeding 95% after 2 h of electrolysis. Furthermore, it shows universal applicability in the electrooxidation of other alcohol/aldehyde substrates, yielding efficiencies of 90-99%. This work not only provides guidance for advanced electrocatalysts design toward alcohol/aldehyde oxidation but also offers insights into the utilization of biomass-derived platform chemicals.

Photocatalytic upcycling of polylactic acid to alanine by sulfur vacancy-rich cadmium sulfide

Photocatalytic conversion has emerged as a promising strategy for harnessing renewable solar energy in the valorization of plastic waste. However, research on the photocatalytic transformation of plastics into valuable nitrogen-containing chemicals remains limited. In this study, we present a visible-light-driven pathway for the conversion of polylactic acid (PLA) into alanine under mild conditions. This process is catalyzed by defect-engineered CdS nanocrystals synthesized at room temperature. We observe a distinctive volcano-shaped relationship between sulfur vacancy content in CdS and the corresponding alanine production rate reaching up to 4.95 mmol/g catalyst/h at 70 oC. Ultraviolet-visible, photocurrent, electrochemical impedance, transient absorption, photoluminescence, and Fourier-transform infrared spectroscopy collectively highlight the crucial role of sulfur vacancies. The surface vacancies serve as adsorption sites for lactic acid; however, an excessive number of vacancies can hinder charge transfer efficiency. Sulfur vacancy-rich CdS exhibits high stability with maintained performance and morphology over several runs, effectively converts real-life PLA products and shows potential in the amination of other polyesters. This work not only highlights a facile approach for fabricating defect-engineered catalysts but also presents a sustainable method for upcycling plastic waste into valuable chemicals.

Catalytic conversion of chitin biomass into key platform chemicals

Chitin is the most abundant nitrogen-containing biomass on Earth and presents a compelling alternative to fossil fuels for chemical production. The catalytic conversion of chitin offers a viable approach for harnessing its inherent carbon and nitrogen contents, contributing to developing a green and sustainable society. This feature article reviews recent advances in shell waste biorefinery, with an emphasis on the contributions from our group. Efficient and sustainable chitin extraction methods are highlighted, along with the conversion of chitin biomass (N-acetyl-D-glucosamine (NAG), D-glucosamine, chitosan, and chitin) into key platform chemicals, mainly including furans, amino/amide sugars, organic acids and amino/amide acids. Catalytic strategies and production pathways are detailed, and current challenges and future research directions in chitin valorization are discussed.

Green coal and lubricant via hydrogen-free hydrothermal liquefaction of biomass

Biocrude derived from biomass via hydrothermal liquefaction (HTL) is a sustainable substitute for petroleum to obtain energy and biochemicals. Upgrading biocrude inevitably faces the trade-off between consuming large amounts of hydrogen via hydrotreating and high yield of solid residue without additional hydrogen. In this work, we report a non-hydrogenated refinery paradigm for nearly complete valorization (~90%), via co-generating green coal and bio-lubricant. The obtained green coal has higher heating values comparable to commercial coals, with a lower fuel ratio and reduced ash content. Viscosity of upgraded vacuum distillate is comparable to that of a lubricant oil. A life cycle assessment confirms 28% reduction in greenhouse gas emission and 35% reduction in energy input of this paradigm compared with conventional hydrotreating biorefinery. This approach presents an environmentally friendly, safe and convenient paradigm for biocrude refining from huge biowaste towards carbon-neutral society.

Advanced Catalysts for the Chemical Recycling of Plastic Waste

Plastic products bring convenience to various aspects of the daily lives due to their lightweight, durability and versatility, but the massive accumulation of post-consumer plastic waste is posing significant environmental challenges. Catalytic methods can effectively convert plastic waste into value-added feedstocks, with catalysts playing an important role in regulating the yield and selectivity of products. This review explores the latest advancements in advanced catalysts applied in thermal catalysis, microwave-assisted catalysis, photocatalysis, electrocatalysis, and enzymatic catalysis reaction systems for the chemical recycling of plastic waste into valuable feedstocks. Specifically, the pathways and mechanisms involved in the plastics recycling process are analyzed and presented, and the strengths and weaknesses of various catalysts employed across different reaction systems are described. In addition, the structure-function relationship of these catalysts is discussed. Herein, it is provided insights into the design of novel catalysts applied for the chemical recycling of plastic waste and outline challenges and future opportunities in terms of developing advanced catalysts to tackle the "white pollution" crisis.

Recycling Valuable Phenol from Polycarbonate Plastic Waste Via Direct Depolymerization and Csp2-Csp3 Bond Cleavage Under Mild Conditions

Upcycling plastic waste into commodity chemicals is recognized as an environmentally benign solution and beneficial for the sustained growth of humanity. Nevertheless, transition metal-free catalysts and energy-efficient conditions pose significant challenges due to the robust mechanical properties of plastics. Here, a strategy for selective production of phenol by upcycling polycarbonate waste via direct depolymerization and Csp2-Csp3 bond cleavage in an aqueous medium under mild conditions is reported. The commercial zeolites efficiently catalyze the depolymerization, Csp2-Csp3 bond hydrolysis, and direct Csp2-Csp3 bond scission at Cα of PC. Among all evaluated zeolites, HY (Si/Al=15) showed excellent catalytic performance, attributed to the ~75 % yield of phenol and ~15 % of acetone. The approach also employs different municipal waste PC for upcycling. Studies reveal that HY (15) exhibits high catalytic efficiency and phenol yield due to its optimum acid sites and textual properties. A scale-up experiment demonstrated that 3.1 g of phenol was produced from 5.0 g of PC, and the mass balance was 90 %. A combination of control experiments, NMR analysis, and DFT studies proposed the reaction pathway. Our findings present a sustainable avenue for upcycling PC waste and offer a new way to produce phenol, contributing to the advancement of a circular economy.

A new microporous organic-inorganic hybrid titanium phosphate for selective acetalization of glycerol

We developed a novel strategy for synthesizing a highly acidic microporous hybrid titanium phosphate material (H-TiPOx) by incorporating 5-aminosalicylic acid (5-ASA) into the titanium phosphate framework. This new H-TiPOx serves as a Brønsted acid catalyst, exhibiting remarkable total surface acidity of 5.9 mmol g-1 and it efficiently catalyzes the acetalization of abundant biomass derived glycerol to solketal with over 99% selectivity.

Resource or waste? A perspective of plastics degradation in soil with a focus on end-of-life options. One step beyond

Plastics have surpassed traditional materials across numerous industries due to their versatility, durability, and cost-effectiveness. However, their persistence in ecosystems, particularly in soil, presents serious environmental challenges. This narrative review builds on previous work by analysing over 300 studies on plastics in soil, with a focus on degradation and potential reuse. Special attention is given to research published since 2019. The review classifies plastics by resin type and examines their degradation processes under various soil conditions, covering both conventional and biodegradable polymers. Polyethylene emerges as the most extensively studied polymer, while interest in biodegradable alternatives like polylactic acid (PLA) and polybutylene adipate-co-terephthalate (PBAT) is increasing. Additionally, the review highlights advancements in microplastics research, particularly their interactions with co-contaminants and effects on soil organisms. Despite significant progress, challenges remain in standardizing methods for measuring plastic degradation in soil. The review emphasizes the need for further research to establish consistent methods and reliable indicators for degradation, while also exploring innovative recycling technologies for use in agricultural soil management. It stresses the importance of advancing a circular economy for plastics, integrating policy and practical solutions to reduce environmental impacts.

Polyethylene hydrogenolysis by dilute RuPt alloy to achieve H2-pressure-independent low methane selectivity

Chemical recycling of plastic waste could reduce its environmental impact and create a more sustainable society. Hydrogenolysis is a viable method for polyolefin valorization but typically requires high hydrogen pressures to minimize methane production. Here, we circumvent this stringent requirement using dilute RuPt alloy to suppress the undesired terminal C-C scission under hydrogen-lean conditions. Spectroscopic studies reveal that PE adsorption takes place on both Ru and Pt sites, yet the C-C bond cleavage proceeds faster on Ru site, which helps avoid successive terminal scission of the in situ-generated reactive intermediates due to the lack of a neighboring Ru site. Different from previous research, this method of suppressing methane generation is independent of H2 pressure, and PE can be converted to fuels and waxes/lubricant base oils with only <3.2% methane even under ambient H2 pressure. This advantage would allow the integration of distributed, low-pressure hydrogen sources into the upstream of PE hydrogenolysis and provide a feasible solution to decentralized plastic upcycling.

Ultra-Narrow Alkane Product Distribution in Polyethylene Waste Hydrocracking by Zeolite Micro-Mesopore Diffusion Optimization

Plastic pollution poses a pressing environmental challenge in modern society. Chemical catalytic conversion has emerged as a promising solution for upgrading waste plastics into valuable liquid alkanes and other high value products. However, the current methods yield mixed products with a wide carbon distribution. To address this challenge, we present a bifunctional catalytic system consisting of β zeolite mixed hierarchical Pt@Hie-TS-1, designed for the conversion of low-density polyethylene (LDPE) into liquid alkanes. This system achieves a 94.0 % yield of liquid alkane, with 84.8 % of C5-C7 light alkanes. Combined with in situ FTIR and molecular dynamics simulation, the shape-selective mechanisms is elucidated, which ensures that only olefins of the appropriate size can diffuse to the encapsulated Pt sites within the zeolite for hydrogenation, resulting in an ultra-narrow product distribution. Furthermore, by optimizing the micro-mesopores of Pt@Hie-TS-1, the scaling relationship between the pore structure and the conversion/selectivity is identified. The rapid diffusion of olefins within these micro-mesopores significantly enhances the catalytic efficiency. Our findings contribute to the design of efficient catalysts for plastic waste valorization.

Visible Light-Switchable Lattice Oxygen Sites for Selective C-H and C(O)-C Bond Electrooxidation

Lattice-oxygen is highly oxidizable, ideal for electrocatalytic C-H oxidation but insufficient alone for C(O)-C bond cleavage due to the non-removable nature of lattice sites. Here, we present a visible light-assisted electrochemical method of in situ formulating removable lattice-oxygen sites in a nickel-oxyhydroxide (ESE-NiOOH) electrocatalyst. This catalyst efficiently converts aromatic alcohols and carbonyls with C(O)-C fragments from lignin and plastics into benzoic acids (BAs) with high yields (83-99 %). Without light irradiation, ESE-NiOOH's intrinsic lattice-oxygen is non-removable and inert for C(O)-C bond cleavage. In situ characterizations show light-induced lattice-oxygen removal and regeneration via OH- refilling. Theoretical calculations identify the nucleophilic oxygen attack on ketone-derived carbanion as a rate-determining step, which can be remarkably facilitated by removable lattice-oxygen to activate α-C-H bonds. As a proof-of-concept, an "electrochemical funnel" strategy is developed for high-efficiency upgrading aromatic mixtures with C(O)-C moieties into BA with up to 94 % yield. This in situ removal-regeneration approach for lattice sites opens an avenue for the tailored design of interfacial electrocatalysts to selectively upcycle waste carbon sources into valuable products.

Catalytic Hydrodeoxygenation of Mixed Plastic Wastes into Sustainable Naphthenes

The chemical upcycling of plastic wastes by converting them into valuable fuels and chemicals represents a sustainable approach as opposed to landfilling and incineration. However, it encounters challenges in dealing with mixed plastic wastes due to their complex composition and sorting/cleaning costs. Here, we present a one-pot hydrodeoxygenation (HDO) method for converting mixed plastic wastes containing poly(ethylene terephthalate) (PET), polycarbonate (PC), and poly(phenylene oxide) (PPO) into sustainable naphthenes under mild reaction conditions. To facilitate this process, we developed a cost-effective, contaminant-tolerant, and reusable Ni/HZSM-5 bifunctional catalyst through an ethylene glycol-assisted impregnation method. The metallic Ni site plays a pivotal role in catalyzing C-O and C-C cleavages as well as hydrogenation reactions, while the acidic site of HZSM-5 facilitates dehydration and isomerization reactions. The collaboration between metal and acid dual sites on Ni/HZSM-5 enabled efficient HDO of a wide range of substrates, including bottles, textile fibers, pellets, sheets, CDs/DVDs, and plastics without cleaning or pigments removal and even their various mixtures, into naphthenes with a high yield up to 99% at 250 °C and 4 MPa H2 within 4-6 h. Furthermore, the metal-acid balance of the Ni/HZSM-5 catalyst is crucial for determining both HDO activity and product distribution. This proposed one-pot HDO process utilizing earth-abundant metal catalysts provides a promising avenue toward practical valorization of mixed plastic wastes.

Selective Oxidation of Polyesters via PdCu-TiO2 Photocatalysts in Flow

Catalytic upcycling of plastic wastes offers a sustainable circular economy. Selective conversion of the most widely used polyester, polyethylene terephthalate (PET), under ambient conditions is practically attractive because of low energy consumption and carbon footprint. Here, we report selective, aerobic conversion of PET in a flow reactor using TiO2 photocatalyst modified with atomic Pd and metallic PdCu (Pd1Cu0.4-TiO2) under ambient conditions. We demonstrate that atomically synergistic Pd1Cu0.4-TiO2 exhibits a formate evolution of 4707 μmol g-1 h-1 with a selectivity of 92.3% together with trace COx released. Importantly, we show that this corresponds to 10-103 times greater activity than reported photocatalytic systems. We confirm that synergy between atomic Pd and metallic PdCu boosts directional charge transfer and oxygen-induced C-C cleavage and inhibits product decomposition. We conclude that photocatalytic waste plastic-to-chemical conversion is sustainable via targeted engineering of atomically synergistic catalysts and reaction systems.

Eutectic Strategy for the Solvent-Free Synthesis of Hydrophobic Cellulosic Cross-Linked Networks with Broad Multifunctional Applications

Cellulose-based functional materials play a crucial role in sustainable social development. However, during the material synthesis process, there is typically significant reliance on various solvent systems for macroscopic- or molecular-scale functionalization modifications. In this study, an innovative hydrophobic eutectic solvent (HES) was developed using ethyl cellulose (EC) and thymol (Thy) without any external solvents. Utilizing this homogeneous system, it is convenient to chemically modify the components without any catalyst. Furthermore, a hydrophobic cellulosic cross-linked network (HCCN) can be successfully prepared through in situ photopolymerization. The HCCN film exhibits high transparency, excellent mechanical properties, chemical stability, and durability. The EC/Thy prepolymer system also demonstrates favorable processability for the preparation of various polymeric materials. Additionally, the applicability of other biomasses and derivatives based on the eutectic strategy has been verified. The methodology proposed in this study offers novel insights into the green and solvent-free preparation of biomass functional materials.

Microwave-Assisted Pyrolysis-A New Way for the Sustainable Recycling and Upgrading of Plastic and Biomass: A Review

The efficient utilization of organic solid waste resources can help reducing the consumption of conventional fossil fuels, mitigating environmental pollution, and achieving green sustainable development. Due to its dual nature of being both a resource and a source of pollution, it is crucial to implement suitable recycling technologies throughout the recycling and upgrading processes for plastics and biomass, which are organic solid wastes with complex mixture of components. The conventional pyrolysis and hydropyrolysis were summarized for recycling plastics and biomass into high-value fuels, chemicals, and materials. To enhance reaction efficiency and improve product selectivity, microwave-assisted pyrolysis was introduced to the upgrading of plastics and biomass through efficient energy supply especially with the aid of catalysts and microwave absorbers. This review provides a detail summary of microwave-assisted pyrolysis for plastics and biomass from the technical, applied, and mechanistic perspectives. Based on the recent technological advances, the future directions for the development of microwave-assisted pyrolysis technologies are predicted.

Innovations in plastic remediation: Catalytic degradation and machine learning for sustainable solutions

Plastic pollution is an extreme environmental threat, necessitating novel restoration solutions. The present investigation investigates the integration of machine learning (ML) techniques with catalytic degradation processes to improve plastic waste management. Catalytic degradation is emphasized for its efficiency and selectivity, while several machine learning techniques are assessed for their capacity to enhance these processes. The review goes into ML applications for forecasting catalyst performance, determining appropriate reaction conditions, and refining catalyst design to improve overall process performance. Briefing about the reinforcement, supervised, and unsupervised learning algorithms that handle all complex data and parameters is explained. A techno-economic study is provided, evaluating these ML-driven system's performance, affordability, and environmental sustainability. The paper reviews how the novel method integrating ML with catalytic degradation for plastic cleanup might alter the process, providing new insights into scalable and sustainable solutions. This review emphasizes the usefulness of these modern strategies in tackling the urgent problem of plastic pollution by offering a comprehensive examination.

Selective hydrogenolysis of the Csp2-O bond in the furan ring using hydride-proton pairs derived from hydrogen spillover

Selective hydrogenolysis of biomass-derived furanic compounds is a promising approach for synthesizing aliphatic polyols by opening the furan ring. However, there remains a significant need for highly efficient catalysts that selectively target the Csp2-O bond in the furan ring, as well as for a deeper understanding of the fundamental atomistic mechanisms behind these reactions. In this study, we present the use of Pt-Fe bimetallic catalysts supported on layered double hydroxides [PtFe x /LDH] for the hydrogenolysis of furanic compounds into aliphatic alcohols, achieving over 90% selectivity toward diols and triols. Our findings reveal that the synergy between Pt nanoparticles, atomically dispersed Pt sites and the support facilitates the formation of hydride-proton pair at the Pt δ+⋯O2- Lewis acid-base unit of PtFe x /LDH through hydrogen spillover. The hydride specifically targets the Csp2-O bond in the furan ring, initiating an SN2 reaction and ring cleavage. Moreover, the presence of Fe improves the yield of desired alcohols by inhibiting the adsorption of vinyl groups, thereby suppressing the hydrogenation of the furan ring.

Novel Feruloyl Esterase for the Degradation of Polyethylene Terephthalate (PET) Screened from the Gut Microbiome of Plastic-Degrading Mealworms (Tenebrio Molitor Larvae)

Mealworms (Tenebrio molitor) larvae can degrade both plastics and lignocellulose through synergistic biological activities of their gut microbiota because they share similarities in chemical and physical properties. Here, a total of 428 genes encoding lignocellulose-degrading enzymes were screened from the gut microbiome of T. molitor larvae to identify poly(ethylene terephthalate) (PET)-degrading activities. Five genes were successfully expressed in E. coli, among which a feruloyl esterase-like enzyme named TmFae-PETase demonstrated the highest PET degradation activity, converting PET into MHET (0.7 mgMHETeq ·h-1·mgenzyme-1) and TPA (0.2 mgTPAeq ·h-1·mgenzyme-1) at 50 °C. TmFae-PETase showed a preference for the hydrolysis of ferulic acid methyl ester (MFA) in the presence of both PET and MFA. Site-directed mutagenesis and molecular dynamics simulations of TmFae-PETase revealed similar catalytic mechanisms for both PET and MFA. TmFae-PETase effectively depolymerized commercial PET, making it a promising candidate for application. Additionally, the known PET hydrolases IsPETase, FsC, and LCC also hydrolyzed MFA, indicating a potential origin of PET hydrolytic activity from its lignocellulosic-degrading abilities. This study provides an innovative strategy for screening PET-degrading enzymes identified from lignocellulose degradation-related enzymes within the gut microbiome of plastic-degrading mealworms. This discovery expands the existing pool of plastic-degrading enzymes available for resource recovery and bioremediation applications.

Catalytic upcycling of waste polyethylene to fuels over a nanosized beta zeolite under mild conditions

We herein report that a nanosized beta zeolite can achieve the upcycling of waste polyethylene into gasoline-range fuels under mild conditions. High accessibility to rich acidic sites intrinsic to the nanosized beta zeolite is crucial to the cracking of polyethylene, leading to a high fuel yield of over 90% at 250 °C for 3 h.

Optimization of PET depolymerization for enhanced terephthalic acid recovery from commercial PET and post consumer PET-bottles via low-temperature alkaline hydrolysis

The increasing demand for plastic has resulted in a surge in plastic waste production. Polyethylene terephthalate (PET), commonly used in beverage bottle manufacturing, is only partially recycled, with an estimated recycling rate of just 28.4% in 2019. This accumulation of plastic waste is harmful to the environment and living organisms, necessitating effective recycling methods for PET waste. One promising method is alkaline hydrolysis using NaOH, which can break down PET into its monomer components, terephthalic acid (TPA) and ethylene glycol (EG). This process not only recycles PET efficiently but also manages contaminants effectively, producing high-quality TPA, supporting the development of a circular economy. This study looks into PET depolymerization via alkaline hydrolysis at low temperature by investigating effects of various factors: pH levels, water to ethanol ratio, NaOH concentration, NaOH to PET ratio, reaction time, PET size, reusability of unreacted PET, air plasma pretreatment of PET, and different kinds of PET. Promisingly, PET conversion rates of over 90% and a TPA purity of 99.6% were achieved in this study highlighting the efficacy of alkaline hydrolysis in depolymerizing post-consumer PET waste. Ultimately, this research advances sustainable plastic waste management and supports the integration of PET into a circular economy framework.

Inverse ceria-nickel catalyst for enhanced C-O bond hydrogenolysis of biomass and polyether

Regulating interfacial electronic structure of oxide-metal composite catalyst for the selective transformation of biomass or plastic waste into high-value chemicals through specific C-O bond scission is still challenging due to the presence of multiple reducible bonds and low catalytic activity. Herein, we find that the inverse catalyst of 4CeOx/Ni can efficiently transform various lignocellulose derivatives and polyether into the corresponding value-added hydroxyl-containing chemicals with activity enhancement (up to 36.5-fold increase in rate) compared to the conventional metal/oxide supported catalyst. In situ experiments and theoretical calculations reveal the electron-rich interfacial Ce and Ni species are responsible for the selective adsorption of C-O bond and efficient generation of Hδ- species, respectively, which synergistic facilitate cleavage of C-O bond and subsequent hydrogenation. This work advances the fundamental understanding of interfacial electronic interaction over inverse catalyst and provides a promising catalyst design strategy for efficient transformation of C-O bond.

Nature-Inspired Strategies for Sustainable Degradation of Synthetic Plastics

Synthetic plastics have become integral to our daily lives, yet their escalating production, limited biodegradability, and inadequate waste management contribute to environmental contamination. Biological plastic degradation is one promising strategy to address this pollution. The inherent chemical and physical properties of synthetic plastics, however, pose challenges for microbial enzymes, hindering the effective degradation and the development of a sustainable biological recycling process. This Perspective explores alternative, nature-inspired strategies designed to overcome some key limitations in currently available plastic-degrading enzymes. Nature's refined degradation pathways for natural polymers, such as cellulose, present a compelling framework for the development of efficient technologies for enzymatic plastic degradation. By drawing insights from nature, we propose a general strategy of employing substrate binding domains to improve targeting and multienzyme scaffolds to overcome enzymatic efficiency limitations. As one potential application, we outline a multienzyme pathway to upcycle polyethylene into alkenes. Employing nature-inspired strategies can present a path toward sustainable solution to the environmental impact of synthetic plastics.