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.

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.

Liquid-phase exfoliation of 2D transition metal dichalcogenides (TMDs) nanosheets in water is critical for their practical applications towards advanced thin-film electronics and ionotronics. We here report a versatile strategy for liquid-phase exfoliation of clay-like water-swollen TMD multilayers into delaminated 2D TMD nanosheets (including MoS2, WS2, MoSe2, etc.) with thin thicknesses of < 2 nm (e.g., 1.4 nm of MoS2) and high nanosheet concentrations. The delaminated TMD nanosheets can form stable colloidal dispersions in water with low Zeta potentials of <–32 mV over a month, and undergo phase transformation upon annealing from metallic 1 T phase to semiconducting 2H phase. These nanosheets can be coated on various circuit substrates as thin-film ionotronics; for example, an ionotronic device with an as-delaminated MoS2 channel achieves a high transconductance of 23 µS at a low operating voltage of −0.2 V. The delaminated TMDs dispersions are capable of co-dispersing other nanomaterials including 2D MXene and graphene, and 1D carbon nanotube and cellulose nanofibrils, forming stable colloidal co-dispersions in water offering a platform to fabricate multifunctional TMD-based nanocomposite films with high electromechanical integrity. Examples of MoS2/MXene films show an electronic conductivity of 1.66 × 105 S m−1 and a tensile strength of 70 MPa, higher than pure MoS2 films of 1.08 × 104 S m−1 and 55 MPa, and MoS2/CNF films with a higher tensile strength of 178 MPa and their hydrogel films presenting a mixed electronic/ionic conductivity of 18.2/0.16 S m−1. These outcomes promise potentially scalable applications in neuromorphic ionotronics, flexible electronics, energy storage, etc.

Membranes and separators are crucial components in many processes and devices. The state-of-the-art fossil-based membranes have a high carbon footprint, and polyfluorinated membranes are increasingly phased out. These limitations lead to an inevitable transition that calls for carbon-neutral membranes with the same or even better performance that can be produced at scale and low cost. Cellulose membranes have the potential to fulfill these criteria if they can be tuned for different purposes. A way to tailor cellulose membranes by preparing them from cellulose fibrils of different refining degrees is presented. The membranes’ effective pore size and permeability to PEG, Fluorescein, and different ions were characterized. The membranes were efficiently used as separators in aqueous-based Zn-ion batteries and PEDOT supercapacitors. This work demonstrates a route toward high-performing and versatile cellulose membranes that can be produced at scale in a more sustainable membrane industry.

Polymer binder selection greatly impacts electrode performance, production, and recyclability in batteries and energy storage systems. We introduce a novel family of polymer binders that provide several key advantages over traditional binders in Li-ion batteries. Our findings show that in-situ cross-linked networks of eco-friendly polyesters bearing pendant carboxylic moieties can serve as superior binders for electrodes. When tested specifically in high‑silicon-content anodes, the electrodes exhibit high initial coulombic efficiency and sustain impressive specific capacity retention after 300 cycles. They reach approximately 2500 mAh/g, compared to 1580 mAh/g for electrodes using conventional PAA binders. Furthermore, the anode shows stable cycling performance when paired with NMC532 cathodes in full Li-ion cell tests. Notably, the transition of silicon from intermediate phases to its fully lithiated state is more efficient with the polyester binder, attributed to the formation of a more stable solid-electrolyte interphase (SEI) layer and reduced impedance. We assign the high performance of our binder to the presence of the polar groups, e.g. carbonyl, in the primary polymer chain, along with the end functional moieties, promoting Li+ solvation and transport, resulting in a high ionic conductivity of the binder. Moreover, the inherent flexibility in the formulations of the polyesters enables fine-tuning of properties such as adhesion, elasticity, and a suitable glass transition temperature, all of which could be customized to optimize battery performance. Produced from renewable feedstocks and adopting water-based or solvent-free fabrication processes, these polyesters offer a fully sustainable solution from production to recycling at the end of the battery's life.

Developing ionotronic interface layers for zinc anodes with superior mechanical integrity is one of the efficient strategies to suppress the growth of zinc dendrites in favor of the cycling stability of aqueous zinc-ion batteries (AZIBs). Herein, we assembled robust 2D MXene-based hydrogel films cross-linked by 1D cellulose nanofibril (CNF) dual networks, acting as interface layers to stabilize Zn anodes. The MXene-CNF hydrogel films integrated multifunctionalities, including a high in-plane toughness of 18.39 MJ m-3, high in-plane/out-of-plane elastic modulus of 0.85 and 3.65 GPa, mixed electronic/ionic (ionotronic) conductivity of 1.53 S cm-1 and 0.52 mS cm-1, and high zincophilicity with a high binding energy (1.33 eV) and low migration energy barrier (0.24 eV) for Zn2+. These integrated multifunctionalities, endowed with coupled multifield effects, including strong stress confinement and uniform ionic/electronic field distributions on Zn anodes, effectively suppressed dendrite growth, as proven by experiments and simulations. An example of the MXene-CNF|Zn showed a reduced nucleation overpotential of 19 mV, an extended cycling life of over 2700 h in Zn||Zn cells, and a high capacity of 323 mAh g-1 in Zn||MnO2 cells, compared with bare Zn. This work offers an approach for exploring mechanically robust 1D/2D ionotronic hydrogel interface layers to stabilize the Zn anodes of AZIBs.

The solid-state field-effect transistor, FET, and its theories were paramount in the discovery and studies of graphene. In the past two decades another transistor based on conducting polymers, called organic electrochemical transistor (ECT), has been developed and largely studied. The main difference between organic ECTs and FETs is the mode and extent of channel doping; while in FETs the channel only has surface doping through dipoles, the mixed ionic-electronic conductivity of the channel material in organic ECTs enables bulk electrochemical doping. As a result, organic ECTs maximize conductance modulation at the expense of speed. To date ECTs have been based on conducting polymers, but here we show that MXenes, a class of 2D materials beyond graphene, enable the realization of electrochemical transistors (ECTs). We show that the formulas for organic ECTs can be applied to these 2D ECTs and used to extract parameters like mobility. These MXene ECTs have high transconductance values but low on-off ratios. We further show that conductance switching data measured using ECT, in combination with other in situ-ex situ electrochemical measurements, is a powerful tool for correlating the change in conductance to that of the redox state, to our knowledge, this is the first report of this important correlation for MXene films. 2D ECTs can draw great inspiration and theoretical tools from the field of organic ECTs and have the potential to considerably extend the capabilities of transistors beyond those of conducting polymer ECTs, with added properties such as extreme heat resistance, tolerance for solvents, and higher conductivity for both electrons and ions than conducting polymers.

Organic electrochemical transistors (OECTs) are promising devices for bioelectronics, such as biosensors. However, current cleanroom-based microfabrication of OECTs hinders fast prototyping and widespread adoption of this technology for low-volume, low-cost applications. To address this limitation, a versatile and scalable approach for ultrafast laser microfabrication of OECTs is herein reported, where a femtosecond laser to pattern insulating polymers (such as parylene C or polyimide) is first used, exposing the underlying metal electrodes serving as transistor terminals (source, drain, or gate). After the first patterning step, conducting polymers, such as poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS), or semiconducting polymers, are spin-coated on the device surface. Another femtosecond laser patterning step subsequently defines the active polymer area contributing to the OECT performance by disconnecting the channel and gate from the surrounding spin-coated film. The effective OECT width can be defined with high resolution (down to 2 µm) in less than a second of exposure. Micropatterning the OECT channel area significantly improved the transistor switching performance in the case of PEDOT:PSS-based transistors, speeding up the devices by two orders of magnitude. The utility of this OECT manufacturing approach is demonstrated by fabricating complementary logic (inverters) and glucose biosensors, thereby showing its potential to accelerate OECT research.

Interpolymer association in aqueous solutions is essential for many industrial processes, new materials design, and the biochemistry of life. However, our understanding of the association mechanism is limited. Classical theories do not provide molecular details, creating a need for detailed mechanistic insights. This work consolidates previous literature with complementary isothermal titration calorimetry (ITC) measurements and molecular dynamics (MD) simulations to investigate molecular mechanisms to provide such insights. The large body of ITC data shows that intermolecular bonds, such as ionic or hydrogen bonds, cannot drive association. Instead, polymer association is entropy-driven due to the reorganization of water and ions. We propose a unifying entropy-driven association mechanism by generalizing previously suggested polyion association principles to include nonionic polymers, here termed polydipoles. In this mechanism, complementary charge densities of the polymers are the common denominators of association, for both polyions and polydipoles. The association of the polymers results mainly from two processes: charge exchange and amphiphilic association. MD simulations indicate that the amphiphilic assembly alone is enough for the initial association. Our proposed mechanism is a step toward a molecular understanding of the formation of complexes between synthetic and biological polymers under ambient or biological conditions.