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Sodium-metal batteries are promising candidates for low-cost, large-format energy storage systems. However, sodium-metal batteries suffer from high interfacial resistance between the electrodes and the solid electrolyte, leading to poor electrochemical performance. We demonstrate a sodium superionic conductor (NASICON) with an oriented porous framework of sodium aluminum titanium phosphate (NATP) fabricated by the freeze-casting technique, which shows excellent properties as a solid electrolyte. Using X-ray computed tomography, we confirm the uniform low-tortuosity channels present along the thickness of the scaffold. We infiltrated the porous NATP scaffolds with sodium vanadium phosphate (NVP) cathode nanoparticles achieving mass loadings of ∼3-4 mg cm -2 , which enables short sodium ion diffusion path lengths. For the resulting hybrid cell, we achieved a capacity of ∼90 mAh g -1 at a specific current of 50 mA g -1 (∼300 Wh kg -1 ) for over 100 cycles with ∼94% capacity retention. Our study offers valuable insights for the design of hybrid solid electrolyte-cathode active material structures to achieve improved electrochemical performance through low-tortuosity ion transport networks.

Increased occurrence of antimicrobial resistance leads to a huge burden on patients, the healthcare system, and society worldwide. Developing antimicrobial materials through doping rare-earth elements is a new strategy to overcome this challenge. To this end, we design antibacterial films containing CeO 2- x -TiO 2 , xanthan gum, poly(acrylic acid), and hyaluronic acid. CeO 2- x -TiO 2 inks are additionally integrated into a hexagonal grid for prominent transparency. Such design yields not only an antibacterial efficacy of ∼100% toward Staphylococcus aureus and Escherichia coli but also excellent antifog performance for 72 h in a 100% humidity atmosphere. Moreover, FluidFM is employed to understand the interaction in-depth between bacteria and materials. We further reveal that reactive oxygen species (ROS) are crucial for the bactericidal activity of E. coli through fluorescent spectroscopic analysis and SEM imaging. We meanwhile confirm that Ce 3+ ions are involved in the stripping phosphate groups, damaging the cell membrane of S. aureus . Therefore, the hexagonal mesh and xanthan-gum cross-linking chains act as a reservoir for ROS and Ce 3+ ions, realizing a long-lasting antibacterial function. We hence develop an antibacterial and antifog dual-functional material that has the potential for a broad application in display devices, medical devices, food packaging, and wearable electronics.

The development of visible light-active photocatalysts is essential for increasing the conversion efficiency of solar energy into hydrogen (H 2 ). Here, we present a facile method for nitrogen doping of monolithic titanium dioxide (TiO 2 ) nanoparticle-based aerogels to activate them for visible light. Plasma-enhanced chemical vapor deposition at low temperature enables efficient incorporation of nitrogen into preformed TiO 2 aerogels without compromising their advantageous intrinsic characteristics such as large surface area, extensive porosity, and nanoscale properties of the semiconducting building blocks. By balancing the dopant concentration and the defects, the nitridation improves optical absorption and charge separation efficiency. The nitrogen-doped TiO 2 nanoparticle-based aerogels loaded with palladium (Pd) nanoparticles show a significant enhancement in visible light-driven photocatalytic H 2 production (3.1 mmol h -1 g -1 ) with excellent stability over 5 days. With this method, we introduce a powerful tool to tune the properties of nanoparticle-based aerogels after synthesis for a specific application, as exemplified by visible light-driven H 2 production.

Developing efficient energy storage technologies is at the core of current strategies toward a decarbonized society. Energy storage systems based on renewable, nontoxic, and degradable materials represent a circular economy approach to address the environmental pollution issues associated with conventional batteries, that is, resource depletion and inadequate disposal. Here we tap into that prospect using a marine biopolymer together with a water-soluble polymer to develop sodium ion battery (NIB) separators. Mesoporous membranes comprising agarose, an algae-derived polysaccharide, and poly(vinyl alcohol) are synthesized via nonsolvent-induced phase separation. Obtained membranes outperform conventional nondegradable NIB separators in terms of thermal stability, electrolyte wettability, and Na + conductivity. Thanks to the good interfacial adhesion with metallic Na promoted by the hydroxyl and ether functional groups of agarose, the separators enable a stable and homogeneous Na deposition with limited dendrite growth. As a result, membranes can operate at 200 μA cm -2 , in contrast with Celgard and glass microfiber, which short circuit at 50 and 100 μA cm -2 , respectively. When evaluated in Na 3 V 2 (PO 4 ) 3 /Na half-cells, agarose-based separators deliver 108 mA h g -1 after 50 cycles at C/10, together with a remarkable rate capability. This work opens up new possibilities for the use of water-degradable separators, reducing the environmental burdens arising from the uncontrolled accumulation of electronic waste in marine or land environments.

The development of efficient, safe, and environmentally friendly energy storage systems plays a pivotal role in moving toward a more sustainable society. Sodium-ion batteries (NIBs) have garnered considerable interest in grid energy storage applications because of the abundance of sodium, low cost, and suitable redox potential. However, NIB technology is still in its infancy, especially with regard to separators. Here we develop a novel separator based on renewable water-soluble cellulose derivatives. Carboxymethyl cellulose (CMC) and hydroxyethyl cellulose (HEC) are cross-linked to afford large-specific-surface-area membranes upon nonsolvent-induced phase separation (NIPS). Long-term galvanostatic cycling in a symmetric Na/Na cell configuration shows an impressive reversible voltage response with a square wave shape of the polarization even after 250 h of cycling, indicating remarkably stable Na plating and stripping with Na dendrite growth suppression. This novel membrane is evaluated as a separator in Na 3 V 2 (PO 4 ) 3 /Na half-cells. After 10 cycles at C/10, the cellulosic separator delivers a capacity of 74 mA·h·g -1 with a 100% Coulombic efficiency compared to that of 61 mA·h·g -1 and 96% obtained for Whatman GF/D as a commercially available separator. Our work provides novel cues for the development of biomass-derived porous membranes to function as battery separators, surpassing the performance of commercially available separators based on fossil resources in terms of capacity retention, Coulombic efficiency, homogeneous plating/stripping of Na, and dendrite growth suppression. These separators, which may be extended to other battery systems, are expected to play a significant role in developing sustainable energy storage systems.

In this work, we report a versatile approach for the development of an in-flow purification water system under solar illumination. Cellulose nanofibrils (CNFs) were impregnated with TiO 2 nanoparticles using water as a solvent to obtain hybrid CNF/TiO 2 monoliths with 98% porosity. The opposite surface potential enables an electrostatically induced direct conjugation between TiO 2 and CNFs. Scanning electron microscopy analysis of the surface morphology of the CNF/TiO 2 monolith shows a homogeneous dense coating of titania nanoparticles onto the interconnected nanofibril network, providing a Brunauer-Emmett-Teller surface area of about 80 m 2 ·g -1 for the hybrid monolith. Furthermore, compression tests reveal a good shape recovery after unloading, thanks to the highly flexible and mechanically stable three-dimensional structure. Finally, the CNF-based hybrids were tested as catalysts for the decomposition of organic pollutants under solar illumination. The tests were performed using a continuous flow reactor with a customized holder, allowing the solution to pass through the monolith. The results reveal a good photocatalytic activity and a long-term stability of the hybrid CNF/TiO 2 monolith toward the decomposition of methyl orange and paracetamol. These features provide a proof of concept for the applicability of the hybrid CNF/TiO 2 monoliths for in-flow purification of water under solar illumination, not only for model dyes but also for organic pollutants of high practical relevance.

We report a solution-phase approach to the synthesis of crystalline copper nanowires (Cu NWs) with an aspect ratio >1000 via a new catalytic mechanism comprising copper ions. The synthesis involves the reaction between copper(II) chloride and copper(II) acetylacetonate in a mixture of oleylamine and octadecene. Reaction parameters such as the molar ratio of precursors as well as the volume ratio of solvents offer the possibility to tune the morphology of the final product. A simple low-cost spray deposition method was used to fabricate Cu NW films on a glass substrate. Post-treatment under reducing gas (5% H 2 + 95% N 2 ) atmosphere resulted in Cu NW films with a low sheet resistance of 24.5 Ω/sq, a transmittance of T = 71% at 550 nm (including the glass substrate), and a high oxidation resistance. Moreover, the conducting Cu NW networks on a glass substrate can easily be transferred onto a polycarbonate substrate using a simple hot-press transfer method without compromising on the electrical performance. The resulting flexible transparent electrodes show excellent flexibility ( R/ R o < 1.28) upon bending to curvatures of 1 mm radius.

A successful strategy to obtain self-supporting (100 microm), UV-absorbing, and, in the visible region, highly transparent TiO2-poly(methyl methacrylate) (PMMA) films was developed. The 15 nm large anatase TiO2 nanocrystals were prepared in a nonaqueous sol-gel approach involving the mixing of Ti(O(i)Pr)4 and benzyl alcohol. The surfaces of the resulting particles were modified with minute amounts of organic ligands in order to make the particles easily dispersible in nonpolar media like xylene and dichloromethane and compatible with PMMA, a polymer of high optical transparency and considerable technical importance. The empirical optimization process of composite fabrication was supplemented by fundamental studies of the crystallization and growth mechanism of anatase particles in a nonaqueous medium. After the preparation of corresponding nanocomposites, the materials were investigated with respect to their UV absorption capability, optical transparency in the visible-wavelength region, and photodegradation.