Paper is an attractive substrate for sustainable and scalable organic electronics; however, its intrinsically insulating nature, the absence of continuous electronic pathways, and the lack of control over mixed ionic–electronic transport have limited its use in electrochemical devices. Here, we nanoengineer cellulose fibers by introducing cationic charges to facilitate a high specific surface area accessible for the adsorption of functional components. We further speed up the diffusion-controlled adsorption through controlled partial fibrillation of the fibers. The combined cationic charge and high surface area enabled high adsorption of the conducting polymer PEDOT:PSS (poly(3,4-ethylenedioxythiophene):polystyrene sulfonate) throughout the internal nanostructure of the fiber wall. The modified fibers were then rapidly transformed to mechanically robust, electrically conductive papers using a conventional papermaking methodology. Post-treatment of papers containing 30 wt% PEDOT:PSS resulted in excellent charge transport and a conductivity as high as 13 S cm−1. Furthermore, electrochemical impedance spectroscopy of wet papers confirmed effective mixed ionic–electronic transport. Finally, to demonstrate the possibilities of the electroactive paper, we integrated the paper as channel materials in organic electrochemical transistors and evaluated them as enzyme-free hydrogen peroxide sensors, achieving a limit of detection of 0.79 µM and a sensitivity of 8.5% per decade, highlighting the potential of combining fiber-wall engineering with scalable processing and device integration.

Sustainable energy storage requires eco-friendly, high-performance electrodes to replace expensive, fossil-fuel-derived carbons. Although biomass-derived carbons are renewable, they typically exhibit limited electrochemical performance. Molybdenum disulfide (MoS₂) possesses high theoretical capacitance but is constrained by restacking and low conductivity. In this study, C-MoS₂ nanocomposites were synthesized by combining activated carbon derived from sugarcane bagasse (surface area: 1070 m2/g) with MoS₂ at different concentrations using a one-step hydrothermal process. The layer-by-layer assembly strategy enabled sequential deposition of the C–MoS₂ composite onto the current collector, leading to enhanced electrochemical performance. The resulting solid-state supercapacitor, utilizing a PVA/H₂SO₄ gel electrolyte, delivered a specific capacitance of 465.87 F/g at 0.67 A/g, an energy density of 32.4 Wh/kg, and a power density of 333.6 W/kg. It retained 97.66% of its capacitance after 5000 cycles. These findings demonstrate the transformation of agricultural waste into a cost-effective, high-performance electrode material, offering a sustainable and potentially scalable solution for next-generation supercapacitors.

The long-term reliability of power transformers is critically dependent on the chemical and mechanical integrity of their lignocellulose-based insulation systems. Despite decades of research, the complex physicochemical mechanisms governing cellulose degradation under thermal, oxidative, hydrolytic, and mechanical stresses remain only partially understood at the molecular level. This review consolidates the current understanding of cellulose degradation in transformer insulation, emphasizing the chemical pathways that drive depolymerization and the formation of key degradation products. Analytical and diagnostic techniques, including direct polymer characterization and indirect oil-based monitoring methods, are evaluated in terms of sensitivity, applicability, and limitations. Recent developments in advanced spectroscopic and scattering methods are discussed as tools for elucidating degradation at the molecular scale. The review also highlights mitigation strategies such as thermally upgraded papers, nanoparticle-enhanced composites, and antioxidant additives. Finally, emerging research directions are proposed, focusing on real-time, non-invasive monitoring, integration of multi-sensor diagnostics with AI, and interdisciplinary approaches to design more durable insulation systems.

Ultrafast interfacial charge transfer in functionalized two-dimensional semiconductors enables precise modulation of their optical and electronic properties. Herein, we report the axial integration of a triply fused porphyrin dimer (TFP) onto few-layer MXene (Ti₃C₂T_x) nanosheets via a stepwise covalent strategy comprising initial pyridine anchoring followed by metal-coordination-driven TFP assembly. Z-scan measurements conducted under nanosecond (532 nm) and femtosecond (800 nm) laser excitation both reveal significantly enhanced nonlinear optical absorption relative to the pristine constituents. This enhancement is mainly attributed to the photoinduced charge transfer from the TFP donor to the Ti₃C₂T_x acceptor matrix, as corroborated by steady-state and transient absorption spectroscopy in conjunction with theoretical calculations. Beyond the demonstration of a high-performance optical limiter, this work establishes a molecular-level design paradigm for engineering interfacial electronic coupling in hybrid two-dimensional architectures subjected to intense optical fields.

Nanocelluloses, as one of the most abundant natural biomass materials on the planet, are conventionally extracted from natural lignocellulosic fibers and present superior combined properties such as high hydrophilicity, low density, high mechanical strength, etc., which show attractive potential as the building blocks to construct different nanocellulose-based hydrogel membranes for different and even for underwater actuator applications. Notably, the reported nanocellulose-based hydrogel membranes for underwater actuators driven by osmotic pressure to date exhibit superior uniaxial actuation behaviors. We herein comprehensively summarize the present progress of nanocellulose-based hydrogel membranes for underwater osmotic actuators, from the building blocks of nanocelluloses to the underwater osmotic actuation (OA) mechanism, including OA, electrochemical OA (ECOA), and corresponding underwater OA applications. Finally, we outline current challenges faced by nanocellulose-based hydrogel membranes for advanced underwater osmotic actuators, such as ion/water transport kinetics in hydrogel membranes, controllability, and output power density. We also propose corresponding promising strategies for addressing these challenges, including the engineering of the nano-building blocks, assembly techniques for nanocellulose-based hydrogel membrane microstructures, programmable actuator configurations, and the integration into remote intelligent actuation systems, aiming to facilitate the high-quality development of the next generation nanocellulose-based underwater osmotic actuators.

MXenes suffer from rapid structural degradation in water, hindering long-term shelf-storage and applications. Current anti-degradation methods either require harsh storage conditions or complex surface treatment, resulting in high costs and intrinsic properties damage. Herein, we propose a versatile (low-cost, intrinsically preserved, high-dispersion, and open-ended) method that enables long-term shelf-storage and operation stability of MXenes by adding ethylene glycol (EG) into MXenes aqueous solution. EG-H2O hydrogen bonding limits water activity and decreases free water ratio, thereby inhibiting their attack on transitional metal atoms on MXene nanosheet surfaces leading to decelerate their degradation, as revealed by molecular dynamics simulations. The limiting-water-activity strategy derived from EG-H2O solvents extended shelf-life of MXenes dispersions over 6 times longer than that of pure water, and notably showed the versatility stabilizing MXenes in the range from Ti3C2Tx to Ti2CTx, Ti3CNTx, and V2CTx, where ~90% EG can be recycled. The versatile limiting-water-activity strategy additionally enabled long-term operation of MXenes in water-based devices: an EG-H2O-processed Ti3C2Tx MXene hydrogels sensor retained up to 95.2% sensitivity over 2-month cycling. This work provides a facile route for long-term shelf-storage and reliable operation of MXenes in water.

Extrusion-based 3D-printing is a promising manufacturing method because it can integrate various nanomaterials, including highly conductive MXenes. Nevertheless, the fabrication of both wet and dry stable 3D-printed structures with MXene has remained challenging due to the difficulty in forming mechanically stable, crosslinked networks with the required rheological properties. In this work, a MXene ink formulation incorporating cellulose nanofibers (CNFs) as rheology modifiers is developed, enhancing structural integrity and enabling a one-step freeze-induced crosslinking process to produce lightweight, porous structures. The 3D-printed structures exhibit remarkable mechanical strength, supporting up to 10,000 times their own weight, while maintaining a conductivity of over 195 S m⁻¹. Additionally, they demonstrate a specific capacitance of 240 F g⁻¹ at 5 mV s⁻¹, highlighting their potential for applications in advanced iontronic devices. A fully 3D-printed supercapacitor concept is showcased in two distinct configurations: in-plane and stacked; demonstrating their structural integrity and electrochemical stability in aqueous environments.

To produce high-performance anode materials for lithium/sodium batteries via sustainable strategies is still one of the most essential tasks in battery research.

To produce high-performance anode materials for lithium/sodium batteries via sustainable strategies is still one of the most essential tasks in battery research. A biomass-based carbon–tin oxide composite (BC/SnO 2 ) is prepared through pyrolysis of birch tree waste using phosphoric acid as an activator and its electrochemical performance as a sustainable anode material in lithium-ion batteries (LIBs) and sodium-ion batteries (NIBs) is tested. The physicochemical characterization results proved that SnO 2 has a remarkable impact on BC/SnO 2 porosity, morphology, and physicochemical features. Due to these favorable properties, the BC/SnO 2 anode exhibited far better performance for LIBs and NIBs than bare carbon (BC). Against Li metal, the BC/SnO 2 anode delivered a specific capacity of 319 mA h g −1 while BC delivered only 93.2 mA h g −1 (at 1C) at the end of 120 cycles. The BC/SnO 2 composite showed excellent rate performances at different current densities, exhibiting a capacity of 453 mA h g −1 at the end of 120 cycles. Upon testing against sodium metal, the BC/SnO 2 composite exhibited better cycling stability than BC (233 mA h g −1 compared with 165 mA h g −1 ) at 100 mA g −1 for 120 cycles. A theoretical investigation of the interactions between BC and SnO 2 was performed using the semi-empirical GFN1-xTB method. The stability of the mixed system at high temperatures was confirmed using molecular dynamic simulations. Finally, we analyzed the electronic properties of the BC/SnO 2 composite and drew conclusions about the electrical conductivity. Therefore, our research strategy helps to produce sustainable high-specific capacity anode materials from biomass resources for building cost-effective metal-ion batteries.

Using molten salts for etching aluminum (Al) away from the MAX phase for MXene synthesis is an attractive alternative method that allows one to avoid the use of toxic hydrofluoric acid (HF) solutions. However, the mechanism of the MAX phase reaction with molten salts remains to date unclear due to the lack of in situ data. Here, we present a detailed in situ time-resolved synchrotron radiation X-ray diffraction study of the MAX phase annealing in molten ZnCl₂ and SnCl₂. The reaction of salts with the MAX phase is found to occur in two stages. The initial period of annealing results in the delamination of two-dimensional (2D) Ti₃C₂ layers, vigorous evolution of AlCl₃ bubbles, and dissolution of Zn in a ZnCl₂ melt. The chlorine-terminated Ti3C2 sheets formed in the delaminated state are restacked into a relatively well-ordered MXene structure (P6₃/mmc, a = 3.071 Å and c = 18.577 Å) during the prolonged annealing in molten salts. Surprisingly, the data recorded directly in molten salts at temperatures up to 873 K demonstrate that Ti₃C₂Cl_x MXene shows no swelling in both liquid ZnCl₂ and SnCl₂. The structure of MXene studied directly in the molten salts is found to be the same as in ex situ experiments performed after cooling and water washing under ambient conditions. The absence of the “pristine” melt-swollen phase indicates a rather different mechanism of MXene formation compared to HF-based solution methods. Formation of MXene by gradually removing Al from the MAX phase starting at the edges of flakes and propagating into the deeper parts of interlayers is not possible, since the molten salt is not capable of penetrating between Cl-terminated Ti₃C₂ layers.

Nucleic acid amplification tests (NAATs) are powerful medical diagnostic tools for point-of-care (POC) and other field applications. However, traditional methods like quantitative PCR (qPCR) require complex, expensive equipment and trained operators, limiting their use to centralized labs. Isothermal alternatives, like Loop-mediated Isothermal Amplification (LAMP), are better adapted for POC devices. Lab-on-PCB systems have the potential to overcome the challenges faced by conventional microfabrication-based systems. This study presents a novel lab-on-PCB device for nucleic acid amplification and electrochemical detection using reverse transcription LAMP (RT-LAMP) of SARS-CoV-2. The system consists of two disposable PCB-based chips making it close to zero cost. One PCB is for heating and nucleic acid amplification, while the other is for electrochemical detection using Cyclic Voltammetry (CV) with a redox-active intercalator. The PCB slides are connected to a compact electronic device (< 10 USD) for controlling the heating and electroanalytical readout. Using this device, we achieved successful rapid (< 1.5 h) nucleic acid amplification and detection at a target concentration of 10 copies/reaction. This work represents a notable step toward developing integrated, portable NAAT devices for POC diagnostics.