ChemSusChem最新文献

Sodium-ion batteries (SIBs) have emerged as promising alternatives to lithium-ion batteries for large-scale energy storage systems, but their development is hindered by the lack of high-performance cathode materials. Na₃V₂(PO₄)₃ (NVP), with a NASICON structure, is a potential cathode candidate; however, its insufficient structural stability and sluggish Na⁺ diffusion kinetics limit its practical applications. Herein, a low-entropy doping strategy is proposed to modify NVP by incorporating multimetal ions (Ti, Cr, Fe, Mn, and Ca) to obtain low-entropy NVP-based materials (NV_2−xM_xP) via a sol–gel method followed by annealing. The optimized NV_1.8M_0.2P delivers a discharge capacity of 97.09 mAh g⁻¹ at 0.5 C, retains 59.19 mAh g⁻¹ at 20 C (60.97% capacity retention), maintains 91.76% capacity after 200 cycles at 1 C, and still retains 85.01% of its initial capacity after 4000 cycles at 10 C. X-ray diffraction (XRD) Rietveld refinement results reveal that low-entropy doping induces unit cell contraction of NV_2−xM_xP, thereby enhancing its structural stability. Partial density of states (PDOS) calculations indicate that this doping strategy reduces the bandgap of NVP from 1.32 to 0.173 eV, significantly enhancing electronic conductivity. Electrochemical impedance spectroscopy and galvanostatic intermittent titration technique reveal that NV_1.8M_0.2P exhibits a lower charge transfer resistance (449.2 Ω) and a significantly higher Na⁺ diffusion coefficient (3.8 × 10⁻⁶ cm² s⁻¹) compared to pristine NVP (8.3 × 10⁻⁸ cm² s⁻¹). Furthermore, ex situ XRD and X-ray photoelectron spectroscopy verify the reversible structural transformation of NV_1.8M_0.2P and the V³⁺ ↔ V⁴⁺ redox reaction during cycling. This low-entropy doping strategy not only provides an effective approach for optimizing NVP-based cathodes but also offers a valuable guideline for designing advanced electrode materials for high-performance SIBs.

The valorization of biomass into renewable, high-performance, adsorbent materials offers a sustainable alternative to conventional synthetic sorbents. In this study, we investigate the potential of lignin derivatives as efficient adsorbents for removing the cationic dye Rhodamine B (RhB) from aqueous solutions. Five organosolv lignin derivatives were synthesized via a one-step process using phenol, catechol, resorcinol, pyrogallol, and hydroquinone as phenolic modifiers to introduce structural diversity. The influence of these modifications on the materials’ physicochemical properties and adsorption behavior was examined. Comprehensive characterization included ³¹P NMR, Brunauer–Emmet–Teller surface area analysis, size exclusion chromatography, thermogravimetric analysis, and dynamic light scattering. Among the derivatives, resorcinol-modified lignin (ReL) showed the highest RhB adsorption capacity (101.2 mg g⁻¹), attributed to its favorable textural properties—high surface area and pore volume—together with increased availability of functional groups, which collectively enhanced adsorption efficiency. Adsorption kinetics for all materials followed the pseudo-second-order model, indicating chemisorption as the dominant mechanism. Isotherm analyses revealed Langmuir-type monolayer adsorption for ReL, pyrogallol-modified, and hydroquinone-modified lignins. Moreover, ReL demonstrated good recyclability, retaining 62% of its adsorption efficiency after five adsorption–desorption cycles. Collectively, these results highlight the promise of structurally engineered lignin-based adsorbents as cost-effective, efficient, and reusable materials for sustainable wastewater treatment.

Metaraminol is a chiral amino alcohol and plays an important role as a precursor molecule and active pharmaceutical ingredient in industry. Its enzymatic synthesis has been developed in recent years and can serve as an alternative to conventional synthesis routes that use toxic, fossil-based resources. Although the enzymatic two-step reaction toward metaraminol has been intensively investigated in the past, full conversion has never been reached in the amine transaminase-catalyzed step. In this study, we focus on identifying and overcoming the hurdles of the transamination step to reach higher metaraminol yields. Photometric and LC-MS analyses revealed side-product formation as a major drawback for the enzymatic metaraminol synthesis. Besides the oxidation of (R)-3-OH-PAC as well as its imine formation with isopropylamine, we demonstrate for the first time the adduct formation of the cofactor pyridoxal-5’-phosphate with metaraminol. Only by changing the amine transaminase formulation to purified enzyme and increasing the concentration by tenfold, >99% product yield with a metaraminol concentration of 75 mM was reached. Further, we successfully integrated the amine donor l-alanine by applying a continuous product extraction system as an alternative to isopropylamine. We believe that our findings and optimization strategies can also serve as a blueprint for other amine-based syntheses.

Hydrogen is expected to be used as a fuel additive to ammonia, a non-flammable and carbon-free fuel, to improve combustion efficiency. However, the design strategies for developing highly active, nonprecious metal catalysts for ammonia decomposition are not yet well understood. Here, we show that Co/Ba_0.01Mg_0.99O exhibits high activity, with an ammonia conversion of 94.4% and a hydrogen production rate of 3.79 mol g_cat⁻¹ h⁻¹ at 500°C with a WHSV of 60,000 mL g_cat⁻¹ h⁻¹. Comparison of the dopant effects of alkaline earth metal elements elucidates that the high activity of Co/Ba_0.01Mg_0.99O is ascribed to the formation of a specific Co-BaO core–shell-like structure, with highly basic BaO nanoparticles covering the Co particles. The core–shell-like structures were not formed with other alkaline earth elements. Such features facilitate efficient electron donation to Co nanoparticles, promoting N₂ formation. Furthermore, kinetic analysis indicated that doping of alkaline earth metals weakens the adsorption of strongly bound species. Our findings will contribute to the development of cost-effective supported metal catalysts for hydrogen production through ammonia decomposition, leading to the realization of a carbon-neutral society in which ammonia plays a key role.

Condensation polymers are extensively utilized across various industries, including applications in bottles, fibers, films, and engineering materials. As an industrial fundamental method for the synthesis of condensation polymers, the polycondensation process has undergone significant development over the past century. A defining feature of polycondensation is the occurrence of exchange reactions, which are critically important in both polymer synthesis and recycling processes, such as alcohol-ester and acid-alcohol exchange reactions. This review provides an in-depth discussion of exchange reactions, highlighting several representative examples applied in polymer synthesis and recycling. It further explores the underlying reaction mechanisms and reviews relevant studies on polymer synthesis using this polycondensation approach. In light of the persistent challenge posed by plastic pollution, this article also discusses the role of exchange reactions in polymer recycling, with the objective of offering meaningful insights into the sustainable reuse of condensation polymers. Furthermore, the review identifies current limitations of the polycondensation technique and discusses potential directions for future research and development.

The mechanochemical depolymerization of commercial PET feedstocks is successfully demonstrated for a variety of samples representing consumer products without the need for specific sample pretreatment. Complete depolymerization is achieved within 20 min by ball milling it with NaOH under ambient conditions. Samples with a higher initial content of amorphous domains depolymerize more rapidly, as collision energy is more effectively utilized for creating reactive interfaces between NaOH and PET. While thickness has a minor effect compared to crystallinity, thicker samples experience lower reaction rates because their accessible surface area is limited. For low-packing density samples, a reduced rate of depolymerization could be expected due to restricted ball motion, but this effect is overcompensated by the ease at which these samples form interfaces. The success of mechanochemical alkali-depolymerization of PET in a ball mill presents an opportunity for industrial implementation, offering a sustainable approach to polymer upcycling due to its mild reaction conditions and minimal solvent requirements.

The synthesis of value-added chemicals from lignin has gained much attention in recent years. However, despite the extensive use of noble metal-based catalysts and high-pressure hydrogen, the hydrodeoxygenation (HDO) of lignin derivatives is still challenging. In this work, non-noble metal-based heterogeneous catalysts derived from layered double hydroxide have been explored for HDO reaction without molecular hydrogen. A series of CuMgAl (CMA) catalysts has been studied, wherein CMA1.5 catalyst shows a high catalytic activity for HDO of vanillin with 100% conversion and 87% yield of 4-methyl-2-methoxyphenol (MMP) within 30 min at 180°C in isopropyl alcohol. The detailed investigations show that superior catalytic activity is attributable to synergistic role of Cu⁰/Cu⁺ ratio, acidic–basic sites, and oxygen vacancies (O_v). Furthermore, density functional theory studies and various control reactions confirm the reaction mechanism, role of O_v, acidic and basic sites for HDO of vanillin. In addition, catalyst shows excellent activity for various other lignin derivatives, demonstrating its broad substrate scope. The catalyst also exhibits excellent productivity (49.71 mmol_MMP g_cat⁻¹ h⁻¹), superior to earlier reports. Hence, this work can pave the way toward a green and sustainable catalytic transfer HDO of lignin derivatives to value-added chemicals within short reaction times.

The electrochemical oxidation of sugar-derived compounds such as furfural and 5-hydroxymethyl furfural (HMF) to the corresponding carboxylic acids is a crucial step in unlocking biomass as a renewable carbon feedstock. For instance, 2,5-furandicarboxylic acid, the oxidation product of HMF, can replace crude-oil derived terephthalic acid in the ubiquitous polymer polyethylene terephthalate. Hence, establishing an electrochemical process for the refinery of biomass requires oxidation of furfural and HMF with high current densities. It is therefore noteworthy that we show in this work that trace impurities undetectable by NMR spectroscopy and HPLC analysis impair the kinetics of electrochemical HMF and furfural oxidation. We therefore evaluate different methods for the removal of impurities from HMF and furfural that form during synthesis and storage of both chemicals. We find that purification by distillation of furfural and by recrystallization of HMF improves the kinetics of their electrochemical conversion best. Since both procedures can be adopted readily by other labs, the present work provides practical guidelines for the pretreatment of chemicals, which may also prove relevant for the development of processes at scale.

Molybdenum oxide catalysts have been widely investigated as cost-effective electrocatalysts for water electrocatalysis due to their easily tunable electronic structures. However, their oxygen evolution reaction (OER) activities remain limited by their low electrical conductivities and electronically inactive oxidation states, thereby prompting the development of various alternative strategies. Herein, Fe-substituted MoO_x catalysts with controlled lattice distortion and oxygen vacancy concentrations are proposed. Fe-substituted MoO_x is synthesized via aerosol spray pyrolysis and subsequent postannealing to control its interfacial properties. Fe substitution induces spatial segregation from Mo, leading to the formation of a yolk–shell structure that exposes abundant active sites. Furthermore, Mo orbital hybridization improves the electronic structure and greatly enhances electrical conductivity. The optimized yolk–shell-structured FeMoO_x catalyst exhibits excellent performance at a high current density of 100 mA cm⁻², delivering a low overpotential of 294 mV and maintaining stable performance over 100 h. In situ electrochemical analyses reveal that temperature control of the charge distribution enhances oxygen intermediate adsorption and promotes OO bond formation through lattice oxygen species, thereby activating the lattice oxygen mechanism. This study provides mechanistic insights and a practical design strategy toward developing cost-effective, high-performance OER electrocatalysts based on transition-metal-modified molybdenum oxides.

Ferroelectric polarization materials have emerged as a revolutionary pathway for designing efficient heterojunction photocatalysts, offering unique advantages in manipulating charge carrier dynamics through built-in electric fields. This study systematically investigates how the coupling of ferroelectric polarization and strain engineering modulate the electronic structure and optoelectronic properties performance of GaTe/In₂Se₃ heterostructure (HS), aiming to establish structure–activity relationships for multifunctional optoelectronic applications. Reversible switching of band alignment in the GaTe/In₂Se₃ HS from Type-I to Type-II was achieved through biaxial strain and ferroelectric polarization reversal of In₂Se₃ between positive (+P) and negative (−P) states, driven by interfacial charge redistribution and built-in electric field modulation. This work demonstrates that coupling ferroelectric polarization with strain engineering provides a versatile strategy to tailor HS functionalities. Synergistic ferroelectric polarization and strain engineering enable multifunctional optimization of HS, paving the way for adaptive optoelectronic catalytic devices via band alignment and carrier dynamics modulation. This study shows that ferroelectric polarization coupled with strain engineering enables effective tuning of band alignment and carrier dynamics in GaTe/In₂Se₃ heterostructures. Polarization reversal and strain synergistically modulate interfacial electric fields, achieving reversible Type-I/Type-II band switching for multifunctional optoelectronic applications.