While high-mass-loading electrodes are desirable for achieving high energy density of lithium-ion batteries, their large thickness restricts charge transport, compromising electrochemical performance. Here, we introduce stencil-printable graphene on separators for lithium-ion batteries with high-mass-loading electrodes. Graphene nanoflake inks are formulated with shear-thinning properties, allowing stencil printing of uniformly deposited graphene layers with defined shapes onto separators. When used in battery assembly, the printed graphene (PG) facilitates efficient electron transport in adjoining electrodes, promoting electrochemical reaction kinetics and homogeneity. LiFePO₄ (LFP)|Li cells with PG exhibit significantly improved rate performance when compared to those without PG, delivering a specific capacity of 126 mAh g⁻¹ at a rate of 2C with an industrially relevant active material (LFP) loading of 15 mg cm⁻² and a high active material mass ratio of 95 %. Furthermore, PG reinforces cycling stability, offering a robust strategy to advance the electrochemical performance of lithium-ion batteries with high-mass-loading electrodes.

Ammonia (NH₃) is a vital chemical widely used in fertilizers, industry, and as a potential energy carrier. However, conventional ammonia production via the Haber-Bosch process is highly energy-intensive, consuming approximately 13.9 kWh per kg of nitrogen. Additionally, nitrogen-rich wastewater contributes to eutrophication and aquatic toxicity, necessitating sustainable recovery solutions. This study introduces an electrochemical membrane stripping (EMS) system incorporating hydrophobic, electrically conducting membranes (ECMs) to enhance ammonia recovery. By applying a controlled electric field and optimizing cathodic potential and crossflow velocity, the system efficiently transports ammonium (NH₄⁺) toward the cathodic membrane, where a localized pH shift converts it into free ammonia (NH₃), eliminating the need for chemical pH adjustment.

Under optimal conditions, the EMS system achieved 88 % ammonia recovery with a high flux of 37 ± 1.45 g m⁻² d⁻¹, representing a 33.5 % improvement over conventional methods. Mass balance analysis confirmed electromigration as a key transport mechanism, leading to a threefold increase in ammonia concentration at the membrane surface. Additionally, the system demonstrated high energy efficiency, with a specific energy consumption of 2 ± 0.15 kWh per kg of nitrogen, making it a cost-effective alternative for liquid fertilizer production.

As a proof-of-concept, the EMS system was successfully tested on real municipal wastewater, highlighting its practical viability. However, further research is needed to assess long-term stability, scalability, and integration with wastewater treatment infrastructure. This study demonstrates EMS as a promising technology for sustainable nitrogen recovery, supporting circular economy initiatives.

Catalytic conversion of NO_x into ammonia is a significant step towards sustainable energy, requiring efficient materials for environmental NO_x detection and its subsequent reduction to amines. While chemiresistive sensing has been realized as technically distinct from the conventional oxygen reduction reaction (ORR), the development of smart catalytic materials which can detect trace-level NO_x and also demonstrate efficient ORR capabilities is crucial. In this proof-of-concept work, Sb single atoms (SAs) have been monodispersed on a nitrobenzene-intercalated few-layered MnPS₃ crystal-surface, for efficient room-temperature NO₂ detection. The sensing properties have been found to be influenced by polarized-monochromatic light and SA loading, with the response being maximum at an ∼50° polarization angle for green light and 3.5% SA content. Under controlled experimental conditions of humidity and pressure, the abovementioned novel composition exhibited ORR response, with ammonia generated at a weight hourly space velocity of 40 000 ml g_cat⁻¹ h⁻¹ and a rate of 4700 μmol g⁻¹ h⁻¹. X-ray absorption spectroscopy revealed the atomic environment of Sb SAs. Quasi-operando micro-photoluminescence combined with Raman spectroscopy identified the role of the MnPS₃ network in facilitating surface NO₂ adsorption. Theoretical calculations delineated the selective and energetic role of Sb SAs in sensing and initiating the ORR, elucidating the reaction pathway in terms of a reduction in Gibbs energy.

The Haber-Bosch process has provided an energy-intensive way to produce ammonia for over 100 years. However, alternative methods are required to lower pollution and enhance energy efficiency. Unfortunately, key mechanistic insights into the heterogeneous reduction of nitrogen and its intermediates are lacking. The nitrite reduction reaction (NO₂RR) is an important electrochemical reaction in the nitrogen cycle, playing a significant role in ammonia-based energy storage and wastewater remediation. Although the NO₂RR involves the transfer of multiple protons competing with the hydrogen evolution reaction (HER), the effect of the proton donor has not been investigated in heterogeneous electrocatalysis. We now present an electrochemical study of nitrite reduction in four buffer systems acting as proton donors: citrate, phosphate, 2-(N-morpholino)ethanesulfonic acid, and borate buffers. The chosen catalyst was a typical iron- and nitrogen-codoped carbon (FeNC) with atomically dispersed FeN₄ sites. All buffers except borate enhanced the NO₂RR considerably, while the reduction mechanism was independent of buffer identity. The kinetics of the reaction depended more strongly on buffer concentration than on the ${\mathrm{NO}}_2^{-}$ concentration. Furthermore, we propose a double role for the protonated buffer species: a crucial proton donor during the rate-determining reduction of an NO_x intermediate and an efficient pH regulator near the electrode. These key mechanistic insights into heterogeneous nitrite reduction help to understand proton-coupled electrocatalysis and contribute to the development of alternative nitrogen-based fuels.

ABSTRACT: All-organic polymer composites have garnered growing attention due to their improved dielectric performance and the compatibility between polymer matrix and fillers favorable for large-scale processing. Here, two fluorinated molecules with different numbers of fluorine atoms, namely 4,5,6,7-tetrafluoronaphtho[2,1-b:3,4-b’]dithio-phene (F4NT) and 5,6-difluoronaphtho [2,1-b:3,4-b’]dithio-phene (F2NT), are incorporated in polyetherimide (PEI). Traces of organic fillers decouple the conjugated structure of PEI chains, reducing the electron transmission channels under high electric fields. The FNTs with multi-ring coplanar structures enhance the insulation of composites due to the wide-bandgap nature and space-scattering electron effects. The molecular filler with more fluorine atoms proved to be more effective in inhibiting electron transmission and resulted in enhanced breakdown strength (approximately 30%) and significantly reduced high-temperature dielectric loss. Moreover, sulfur atoms with higher polarizability in FNTs contribute to an improved dielectric constant. The simultaneously enhanced dielectric constant and breakdown strength in composite film capacitors result in a higher discharged energy density that is 1.9 times that of pure polymer, accompanied by a high efficiency of 90%. Further preparation of composites based on polyvinylidene difluoride (PVDF) for mechanism investigation reveals that the enhanced dielectric performance is mainly due to enhanced insulation properties in the amorphous area.

The increasing global energy demand necessitates the development of sustainable electrochemical energy technologies. Anion-exchange membrane fuel cells (AEMFCs) present a promising alternative to proton-exchange membrane fuel cells (PEMFCs) due to their ability to utilize platinum-group metal (PGM)-free catalysts, which significantly reduce costs and resource dependency. In this work, we prepare various PGM-free catalysts for the oxygen reduction reaction (ORR) via an ionothermal synthesis using cyclodextrin and magnesium nitrate. The synthesis conditions were optimized and the electrocatalysts were investigated with both physical and electrochemical characterization techniques. The catalysts’ ORR performance was assessed using rotating disk electrode (RDE) measurements and single-cell AEMFC tests. The optimized FeNC-CD3 catalyst exhibited a half-wave potential of 0.90 V vs RHE in 0.1 M KOH in the RDE test and a peak power density of 599 mW cm⁻² in an AEMFC, showcasing its potential as a viable alternative to conventional Pt-based cathode catalysts. This work highlights the critical role of hierarchical porosity in enhancing the ORR activity and paves the way for the development of cost-effective and efficient AEMFC technology.

Metal–organic frameworks (MOFs) are promising precursors for creating metal–nitrogen–carbon (M–N–C) electrocatalysts with high performance, though maintaining their structure during pyrolysis is challenging. This study examines the transformation of a Zn-based MOF into an M–N–C electrocatalyst, focusing on the preservation of the carbon framework and the prevention of Zn aggregation during pyrolysis. A highly porous Zn–N–C electrocatalyst derived from Zn-TAL MOF (where TAL stands for the TalTech-UniTartu Alliance Laboratory) was synthesized via optimized pyrolysis, yielding notable electrocatalytic activity toward oxygen reduction reaction (ORR). Scanning electron microscopy (SEM) and X-ray diffraction spectroscopy (XRD) analyses confirmed that the carbon framework preserved its integrity and remained free of Zn metal aggregates, even at elevated temperatures. Rotating disc electrode (RDE) tests in an alkaline solution showed that the optimized Zn–N–C electrocatalyst demonstrated ORR activity on par with commercial Pt/C electrocatalysts. In an anion-exchange membrane fuel cell (AEMFC), the Zn–N–C material pyrolyzed at 1000 °C exhibited a peak power density of 553 mW cm^–2 at 60 °C. This work demonstrates that Zn-TAL MOF is an excellent precursor for forming hollow Zn–N–C structures, making it a promising high-performance Pt-free electrocatalyst for fuel cells.

Post-use agricultural plastics are often inseparably mixed with crop residues and therefore less recyclable. Hydrothermal processing (HTP) is a viable alternative to increase plastic circularity, valorize biomass, and recover valuable platform chemicals. HTP was used here to co-process a model mixture of low-density polyethylene (LDPE) with wheat straw. Products in all phases were characterized, and the resulting liquid phase was examined for toxicity. Two forms of separated solid products were recovered – a hydrochar derived from the straw, and a polymeric-solid originated from the LDPE portion of the feedstock. The hydrochar had a lower O:C ratio than the feedstock. The polymeric-solid contained hydrochar particles, forming a homogeneous LDPE/hydrochar composite. Liquified and gas products were mainly attributed to straw decomposition, in line with the relative stability of LDPE in sub-critical water. The obtained liquefied products, such as phenolic and heterocyclic compounds, may affect natural microbial communities. Economically viable gases, including propene, methane, and carbon monoxide (CO), were identified in the gas phase.

Concentrated Solar Power [CSP] technologies address one of the challenges associated with intermittent energy sources such as wind and solar by incorporating thermal energy storage [TES], allowing generation to be shifted to periods without solar resources, and providing backup energy during periods with reduced sunlight that can be caused by cloud cover. Furthermore, CSP's ability to operate on gas when TES runs out offers a base load and dispatchable renewable solution in the systems that use a gas generator as a backup, which in the future can rely on hydrogen. Enhancing optical efficiency is a key challenge in CSP technology development, which requires wirelessly controlling the exact aiming orientation of tens of thousands of heliostats within sub-milliradian accuracy, while optically monitoring the field from outside the optical path where a very high temperature is obtained. Another challenge is the minimal number of pixels designated to each heliostat, as the entire solar field is monitored simultaneously. Optical efficiency optimization is also challenging due to the inherent tradeoff between the Ground Cover Ratio (GCR) and the shading and blocking of the mirrors. The heliostat control method proposed in this paper is applicable to solar power tower technology. This study aims to improve the accuracy of the solar field's tracking under shading and blocking by presenting and implementing a novel tracking method and comparing it to prior art. The method is based on monitoring the reflection from a specular curved bar along the vertical and the horizontal edge of the heliostat (or mirror facet). According to the place of the sun's reflection, the deviation from the receiver is obtained. The results show that the triangulation method using a specular curved bar gives an accuracy of 0.8 mrad, which is superior to the prior art, considering shading and blocking. It also provides the best accuracy in the exploitation of pixels. This enhancement in efficiency will bring us closer to achieving 90–95 % availability of renewable electricity at the cost of gas. This advancement stands as a significant stride in our ongoing battle against climate change.

Lithium-ion batteries (LIBs) are the most advanced energy storage systems, meeting the current business, industrial and social demands. Two factors are currently driving the research in the batteries field: first is the constant demand for better performance, and the second is the urgent call to minimize the ecological impacts related to battery manufacturing, employment, and decommission. Biomaterials demonstrate complex and diverse structures and unique physicochemical properties that can be easily modified. These features are very advantageous for the preparation of lithium and Li-ion cell components. The adoption of biomaterials substantially benefits the development of a clean and sustainable battery industry. The main areas of implementing biomaterials in electrodes, separators, and binders for high-energy lithium and LIBs are identified, and the latest achievements in the fields are outlined in this work. While advanced development in the field of LIBs provides solid grounds to consider that the application of biomaterials has great potential, future implementation of such materials in commercial LIBs production is yet to be fully realized, and there is still a need for a large volume of research work. The main points of future work and perspective in this research area are outlined in this review.