The transition from laboratory-scale experiments to industrial-scale production frequently exposes fundamental challenges related to process similarity. In the context of silicon porosification, achieving consistent results during scale-up requires maintaining thermal, kinematic, geometric, and electrochemical (current/potential) similarities. On the example of two stages of upscaling, this work aims to elucidate the principal scaling effects that arise during the electrochemical porosification of silicon and to outline strategies for mitigating them. Through a series of representative examples, the paper highlights how process parameters, reactor geometry, and operating modes influence the resulting pore architecture and uniformity. A novel inline etching tool is presented where the wafers pass over tanks of alternating polarity. This approach has the great benefit that it does not need a backside contact; however, the alternating tank coverage leads to current density fluctuations under potentiostatic operation. A simple COMSOL simulation (Finite Element Method) of the series resistance network of the system is able to explain the fluctuations qualitatively as well as quantitatively. On this basis, design rules for the next-generation inline etching tool are suggested that would reduce the current density fluctuations from about 50 % to less than 10 %.

Sodium-ion batteries (SIBs) are promising next-generation energy-storage systems, yet their low energy density remains a major challenge. An effective strategy to utilizing low-potential anodes is tuning their electrode potentials with respective to an electrolyte potential window. Herein we propose a molecular framework design of electrolyte solvents to rationally tune sodium electrode potential (E_Na). Extending the alkyl chains of phosphate ester solvents upshifted E_Na by up to 0.32 V (tripropyl phosphate vs. trimethyl phosphate) despite similar donor numbers, indicating a dominant steric effect to weaken the Na⁺ solvation. In contrast, cyclic crown ether 15-crown-5 downshifted E_Na by 0.16 V compared to its linear counterpart (tetraglyme) via the formation of a more stable chelate coordination. Furthermore, the magnitude of these steric/structural effects depended strongly on the cation species, leading to large variations in the Na-Li electrode potential difference (ΔE_Na–Li), from 0.53 V in tripropyl phosphate to 0.10 V in 18-crown-6. Machine-learning-based molecular dynamics simulations revealed that the changes in the cation solvation structure, induced by the solvent molecular framework engineering, are responsible for the observed potential shifts. These findings establish solvent molecular framework engineering as a versatile strategy to tune electrode potentials in battery electrolytes.

Electrochemical conversion of CO₂ into calcium carbide in molten salts has emerged as a promising route for carbon capture and utilization, enabling the production of acetylene, an important industrial chemical. However, continuous operation requires a stable oxygen evolution reaction (OER) at the anode while suppressing competing oxidation of carbonate and carbide species that regenerate CO₂. The anodic reaction mechanism in carbide-containing molten salts remains poorly understood. Here, the anodic behavior and durability of the perovskite oxide La_0.7Sr_0.3FeO_3−δ are investigated in molten NaCl–CaCl₂ at 873 K under controlled anionic environments containing O²⁻, CO₃²⁻, and C₂²⁻. Thermodynamic analysis using potential–pO²⁻ diagrams predicts that carbide oxidation occurs at the most negative potential, followed by carbon, oxide, and carbonate oxidation, which agrees with electrochemical measurements and gas analysis. When O²⁻ and CO₃²⁻ coexist, selective oxygen evolution is achieved with a Faradaic efficiency of 81.4 % and a low corrosion rate of 1.94 × 10⁻⁵ g cm⁻² h⁻¹. In contrast, dissolved C₂²⁻ undergoes anodic oxidation at lower potentials, producing amorphous carbon that accelerates electrode degradation and reduces OER efficiency. These results demonstrate that anodic stability is governed by the local anionic environment, highlighting the importance of maintaining O²⁻ and CO₃²⁻ coexistence while suppressing carbide transport to the anode.

Suppressing zincate crossover is necessary for rechargeable alkaline Zn-MnO₂ rechargeable batteries using electrolytic manganese dioxide (EMD). We benchmarked six commercial separators for their ability to block zincate ions while maintaining the transport of hydroxide ions. Among the separators, FAAM-75-PK (FP75), a commercial anion-exchange membrane, exhibited moderate conductivity (5.8 mS cm⁻¹) with the lowest diffusion coefficient of zincate ions (D_Zn = 2.0 × 10⁻⁸ cm² s⁻¹) and a moderate diffusion coefficient of hydroxide ions (D_OH = 3.5 × 10⁻⁵ cm² s⁻¹), leading to the highest permselectivity (D_OH/D_Zn = 1.7 × 10³). In the galvanostatic discharge–charge tests, FP75 exhibited the best capacity retention of 68 % at the 7th cycle. Characterization of the discharged EMD electrodes revealed that FP75 effectively suppressed ZnMn₂O₄ formation at the cathode, favoring Mn₃O₄ formation instead. The low Zn concentration of 6 ppm in the catholyte is consistent with the favored Mn₃O₄ formation. Beaker-cell tests identify a system-dependent zinc concentration threshold. When the Zn/Mn molar ratio exceeds ∼0.05–0.15, product formation shifts toward ZnMn₂O₄ from Mn₃O₄, and thus, the capacity decay accelerates.

It is important to develop a rechargeable battery that is safe and free from resource risk to replace the current lithium–ion battery in various application fields. We have been conducting research and development of aqueous electrolyte batteries with zinc as the negative electrode (anode) through national programs, Research and Development Initiative for Scientific Innovation of New Generation Batteries (RISING, RISING2 and RISING3), commissioned by the New Energy and Industrial Technology Development Organization (NEDO). In RISING2, we demonstrated a full cell that can achieve a target specific energy of 500 Wh kg⁻¹ for a zinc–air system through advancements in elemental technology and full-cell engineering. RISING3 aims to develop a sealed zinc-anode rechargeable battery by developing positive electrode (cathode) materials to replace air electrodes. A notable achievement of this study is proving that the manganese dioxide (MnO₂) prepared through electrolysis (EMD) has good rechargeability in alkaline electrolyte systems, in which the amount of structural water in the oxide determines the discharge capacity for the first one-electron reduction. We also found that the newly developed MnO₂ from the chemical reduction of permanganate (PMD) enables a reversible two-electron reaction even in the electrolyte containing zinc species, in which hetaerolite (ZnMn₂O₄) generally forms to inhibit further electrochemical reactions.

This study demonstrates that the acoustic emission (AE) methodology can be successfully applied to zinc-air battery systems. AE analysis provides real-time insights into mechanically induced events and enables qualitative correlation with electrochemical processes during different operating stages. The method shows high sensitivity to corrosion-driven hydrogen evolution under open-circuit conditions and to oxygen-evolution-related activity in catalyst-based gas diffusion electrodes during charging. In commercial cells, a pronounced increase in AE activity once the cell voltage exceeds 1.8 V indicates the onset of carbon-related degradation, while final AE spikes prior to failure reflect the mechanical manifestation of critical degradation events such as separator rupture or electrode collapse. Overall, the results highlight AE as a powerful diagnostic tool for identifying degradation phenomena in metal–air batteries. Consideration of the observed diffusion limitations and the future implementation of advanced analysis tools, including distribution of relaxation times, equivalent circuit models, and machine-learning approaches, will further refine the understanding of process contributions in next-generation rechargeable battery systems.

Sodium-sulfur (Na/S) batteries are promising low-cost next-generation batteries. In particular, all-solid-state Na/S batteries are expected to demonstrate high capacity at room temperature because sulfur has a high theoretical capacity as a positive electrode active material and sulfide solid electrolytes exhibit high ionic conductivity. However, sulfur is insulating and must be mixed with conductive agents to create both ionic and electronic conductive pathways. In addition, sulfur undergoes a large volume change during cycling, and the solid-solid interface connections are easily lost. Therefore, it is necessary to devise a composite positive electrode design that achieves a high capacity by maintaining the solid-solid interface and activating sulfur redox reactions. In this study, sulfur, mesoporous carbon, and Na₃PS₄ or Na₃SbS₄ are used as composite positive electrodes, and the preparation conditions of the composite positive electrodes are investigated by charge–discharge testing and cross-sectional observations. This study clarifies that the type of sulfide solid electrolytes and its degree of dispersion in the composite electrode significantly modify electronic/ionic percolation pathways and interfacial stability, thereby governing sulfur utilization and cycling retention.

Electrogenerated chemiluminescence (ECL) cells are promising for applications in unique displays due to their simple structure, but further improvements in cell performance have been desired. Herein, we successfully enhanced the luminescent characteristics of the green fluorescent ECL cell by introducing a stilbene derivative as a redox mediator into an anthracene-9,10-diamine derivative solution. 9,10-Bis[phenyl(m-tolyl)-amino]anthracene (TPAA) was used as a luminescent material, while (E,E)-1,4-bis[4-[bis(4-methoxyphenyl)amino]styryl]benzene (TOP-HTM-α1) was used as the mediator. The maximum luminance and current efficiency of the cell with a configuration of indium tin oxide anode/mixed solution/fluorine-doped tin oxide cathode reached 191 cd m⁻² and 1.96 cd A⁻¹, respectively, which are the highest values ever reported in green ECL cells. Moreover, the cell showed a low turn-on voltage (defined as the voltage at 0.01 cd m⁻²) of 2.5 V, which is close to the singlet emission energy of TPAA. We believe that our findings in this study could contribute to the development of advanced ECL display devices.

One of the most critical remaining challenges for extending the lifetime of lithium-ion batteries (LIBs) is the suppression of capacity fading caused by the state-of-charge (SOC) imbalance between the electrodes. Although it has been recognized that side reactions occurring at both the positive and negative electrodes play a crucial role in this degradation process, few theoretical studies have quantitatively related these reactions to battery lifetime. In this work, we formulate the relationship between the rate of side reactions, referred to as the side reaction current (I_SR), and the rate of capacity fading induced by SOC imbalance in LIBs. We first demonstrate that the presence of side reactions establishes local cells within the electrodes, thereby inducing SOC shifts in both the positive and negative electrodes. The types of side reactions responsible for SOC imbalance are then classified and discussed. Furthermore, we describe experimental methods for measuring I_SRs, both those intrinsic to electrode materials and those occurring within LIB cells. Finally, we show that the rate of capacity loss originating from SOC imbalance is governed by the I_SR values of the electrodes and clarify its correlation with conventional lifetime indicators such as Coulombic efficiency and capacity retention. The theoretical framework and equations presented here provide a kinetic basis for analyzing capacity fading caused by the SOC imbalance, offering a unified foundation for evaluating and comparing lifetime improvement strategies in LIBs.

Direct functionalization of benzylic C–H bonds provides an attractive route to access valuable benzylic derivatives, but selective oxidation remains challenging due to overoxidation of the desired products. Herein, we report a new electrochemical strategy for the generation and utilization of benzyl triflates. In this study, benzyl triflates were successfully generated from two-electron oxidation of toluenes, and their formation was directly confirmed by NMR spectroscopy. The anodically generated triflates were subsequently converted into benzylic ethers and thioethers. This approach suppresses overoxidation by generating cationic intermediates under nucleophile-free conditions, which can then be selectively transformed.

The shift towards low-carbon hydrogen via water electrolysis using renewable electricity is crucial for reducing greenhouse gas (GHG) emissions across various industrial sectors. Asahi Kasei, a Japanese chemical company, has leveraged its extensive chlor-alkali electrolysis expertise to develop and demonstrate a large-scale alkaline water electrolysis system, the “Aqualyzer.^†” This paper provides an overview of the core technologies developed for Aqualyzer, including advanced electrolysis components, dynamic control methods, and system simulation technologies. It also details the key test and demonstration facilities, specifically the 10 MW-class system deployed at the Fukushima Hydrogen Energy Research Field (FH2R) and the alkaline water electrolysis pilot test plant comprising four modules in Kawasaki, Japan.

A library of hundreds of metal oxide and metal sulfide photocatalysts has been constructed based on our original strategies of photocatalyst design that were metal cation doping, new valence band formation, and making a solid solution. Various single particulate and Z-scheme photocatalyst systems that are active in visible-light water splitting have been developed. By the doping strategy, SrTiO₃:Rh,Sb and SrTiO₃:Ir,Sb,Al of a single particulate metal oxide photocatalyst were developed for water splitting working under visible light irradiation. BiVO₄ was developed for water oxidation to form O₂ under visible light irradiation by the new valence band formation with Bi6s orbitals. Several types of a Z-scheme system have been constructed by using SrTiO₃:Rh of a H₂-evolving photocatalyst, BiVO₄ of an O₂ evolving photocatalyst, and a suitable electron mediator such as Fe^3+/2+, Co(bpy)₃^3+/2+, reduced graphene oxide (RGO), and poly-3,4-ethylenedioxythiophene (PEDOT). A CuGaS₂-ZnS solid solution photocatalyst was active for sacrificial H₂ evolution, and it was able to be applied to a Z-scheme photocatalyst with BiVO₄ of an O₂-evolving photocatalyst for water splitting without any sacrificial reagents. Novel cocatalysts such as Ag and Rh-Ru were found for photocatalytic CO₂ reduction using water as an electron donor. Ag/NaTaO₃:Ba and Rh-Ru/NaTaO₃:Sr photocatalysts gave 90 % and 10 % of an electron-based selectivity for the CO₂ reduction to form CO and CH₄ accompanied with stoichiometric O₂ evolution even in an aqueous solution under UV irradiation, respectively. A Z-scheme photocatalyst consisting of CuGaS₂-ZnS and BiVO₄ was active for the CO₂ reduction to form CO with 12 % of the selectivity under visible light irradiation in an aqueous suspension system.

We propose an impedimetric biosensor using the bipolar phenomenon with an open bipolar electrode (oBPE). The oBPE platform offers a structurally simple and highly flexible design. The unique electrochemical biosensor consists of a BPE, driving electrodes for detection, and an electrolytic cell as its components. We employed non-faradaic electrochemical impedance spectroscopy to detect biomolecular events occurring on the BPE surface. The biosensor showed a 45 % increase in impedance at 2 kHz after bovine serum albumin adsorption onto the BPE surface. Additionally, the significance of solution resistance, which was uniquely defined by the distance between driving electrodes and a BPE, was demonstrated through changes in impedance. We used the detection system as an immunosensor to detect the binding of C-reactive protein (CRP) to antibody-modified BPE, based on changes in impedance. The biosensor detected the binding of CRP to antibody without the need for redox-active reagents or complex signal amplification steps. The biosensor showed a linear response to the concentration of CRP in the range from 0.001 to 1 µg/mL, comparable to that of conventional three-electrode systems. These findings demonstrate the potential of non-faradaic impedimetric biosensors with an oBPE for sensitive detection of biomolecular events in biochemical analysis.

Thin film solar cells using halide perovskite polycrystals as semiconductors are entering the stage of factory production after their power conversion efficiencies have rapidly improved to 27 %, reaching a level comparable to the highest efficiency of single-crystalline Si solar cells. To ensure stable high efficiency and long device life, further studies on the photovoltaic performance are focused on molecular level improvement of hetero junction interfaces for efficient charge transports. Among inverted p-i-n junction devices which are becoming a major structure in the perovskite photovoltaics, the device using SAMs (self-assembled monolayers) in place of hole transport layer has succeeded in obtaining high efficiencies equivalent to conventional n-i-p devices, Interface molecular engineering, including SAM-based modified interfaces, is essential for reducing charge recombination loss and enhancing photovoltage in power generation. This paper presents research progress on interface engineering for high voltage device performance and our recent efforts to design new structures of perovskite solar cell with SAM-modified hetero-junction interfaces.

Transition metal-doped colloidal quantum dots (QDs) are promising candidates for dual-mode imaging due to their tunable optical properties and potential magnetic functionalities. Here, we report the synthesis and characterization of Mn²⁺-doped AgGaS₂ (AGS) and ZnS-alloyed Ag–Ga–S (AGZS) QDs via a one-pot heating-up method. Upon Mn²⁺ incorporation, both AGS and AGZS QDs exhibited two distinct photoluminescence (PL) peaks originating from the host QDs and doped Mn²⁺ ions, with the relative intensities tunable by varying Mn²⁺-to-total metal cation ratio in the precursor (Mn²⁺/cation_pre). The AGZS QDs prepared with Mn²⁺/cation_pre ratio of 1.1 % exhibited a high PL quantum yield of 45 %, with 40 % of the emission attributed to the d-d transition of Mn²⁺ ions (⁴T₁ → ⁶A₁). Time-resolved PL measurements revealed efficient energy transfer from excitons in the host QDs to doped Mn²⁺ ions, contributing to enhanced Mn²⁺-related emissions. Surface passivation with a ZnS shell followed by ligand exchange with 3-mercaptopropionic acid allowed stable dispersion of AGZS QDs in aqueous media while retaining optical properties. Since the Mn²⁺-doped QDs also exhibited paramagnetic behavior, we investigated the performance of Mn²⁺-doped AGZS QDs as a contrast agent for magnetic resonance imaging (MRI). The intensity of the T₁-weighted MRI signal increased with an increase in the content of doped Mn²⁺. These results demonstrate that Mn²⁺-doped AGZS QDs are promising single-component dual-mode (PL/MRI) nanoprobes for biomedical imaging applications.

A model photocatalyst composed of n-type GaN thin film as a photocatalyst body with a comb shaped electrode composed of Pt layer or Pt/Ti bilayer on the surface was successfully prepared, and photocatalytic and electric properties are investigated. Current-voltage (I-V) curve measurements revealed the formation of Schottky contact between Pt comb and GaN, and ohmic contact between Pt/Ti comb and GaN. In the reaction tests, the GaN model photocatalyst with a Pt/Ti comb showed about three times increased hydrogen evolution rates over the photocatalyst with a solely Pt comb. Under irradiation, about 0.2 V photovoltage at Pt-GaN interface was observed, which prevents electron transfer from the GaN photocatalyst body to Pt cocatalyst, while the photovoltage was eliminated by the introduction of a Ti layer between the Pt and GaN. In-situ photoluminescence (PL) measurement in oxygen ambient confirmed smooth transfer of photoexcited electrons in GaN to Pt/Ti comb, and the degree of quenching indicates efficient charge separation at the working potential. Furthermore, the filling of mid-gap states by electrons was also observed.

Antimony-based sulfide solid electrolytes exhibit high conductivity for alkaline cations. In this study, we synthesized K₃SbS₄ potassium-ion conductors using the mechanochemical method for the nominal compositions with x mol% excess K₂S (x = 0, 5, 10, and 15) to compensate for the chemical impurities in the K₂S reagent. The mechanochemically prepared samples showed X-ray diffraction patterns similar to β-K₃SbS₄ in all the compositions. Raman bands attributed to the SbS₄³⁻ unit were observed in all the samples. The ionic conductivities at 25 °C showed a positive correlation with increasing x, reaching a maximum ionic conductivity of 3.6 × 10⁻⁶ S cm⁻¹ at 10 mol% excess K₂S. Subsequent heat-treatment further enhanced the ionic conductivity, achieving 1.2 × 10⁻⁵ S cm⁻¹ at 25 °C. This improvement is attributed to the nominal composition being close to that of K₃SbS₄ by adjusting the excess amount of K₂S and the increased crystallinity of β-K₃SbS₄.

All-solid-state batteries with sulfide solid electrolytes are promising next-generation energy storage devices owing to their longer lifetimes compared with liquid-type lithium-ion batteries. However, their practical application is hindered by low moisture stability. Few studies have quantitatively compared their moisture stability and underlying mechanisms among electrolyte species. This study systematically evaluates the moisture stability of sulfide solid electrolytes by standardizing particle size and varying electrolyte species, moisture content (dew point), and atmospheric conditions. Sulfide solid electrolytes with different crystal structures, such as Li₆PS₅Cl, Li₃PS₄, and Li₄SnS₄, were exposed to Ar gas flows with dew points from −30 to 0 °C (H₂O concentrations: 0.45–4.8 g m⁻³). H₂S generation followed the order: Li₆PS₅Cl ≫ Li₃PS₄ > Li₄SnS₄. At 0 °C dew point, H₂S gas release was ∼22.7 ml g⁻¹ for Li₆PS₅Cl, ∼0.44 ml g⁻¹ for Li₃PS₄, and ∼0.17 ml g⁻¹ for Li₄SnS₄. Despite variations in H₂S generation, lithium ionic conductivity retention was similar. X-ray photoelectron spectroscopy showed surface hydrolytic decomposition species were observed on Li₆PS₅Cl, whereas Li₃PS₄ and Li₄SnS₄ showed minimal changes. Thermogravimetric analysis revealed clearer hydration in Li₃PS₄ and Li₄SnS₄, causing lower ionic conductivity without H₂S generation. Differences in conductivity reduction are attributed to sulfide unit structures.

A machine learning model that can predict the ionic conductivity of lithium-containing oxides using chemical composition and ionic conductivity data was previously developed. However, this model revealed several limitations, leading to less-than-ideal prediction accuracy. Thus, new models demonstrating improved prediction ability must be developed. This study presents the development of machine learning models for the accurate prediction of ionic conductivity in lithium-containing materials based solely on their chemical composition. The models constructed using the NGBoost and LightGBM algorithms show high compatibility with the training and test data, resulting in high predictive accuracy. The constructed models identify “entropy,” which is considered a key factor in developing ionic conductors, as an important feature. This finding highlights the potential utility of this property from a solid-state chemistry perspective. The developed models demonstrate high predictive accuracy even for previously reported lithium superionic conductor-type materials that were not included in the training dataset. The established models are expected to facilitate efficient material discovery for the development of all-solid-state lithium batteries.

To extend the lifetime of lithium-ion batteries, determining the side-reaction current (I_SR) is essential because capacity fading is mainly caused by the state-of-charge imbalances of positive and negative electrodes. Among the three types of I_SR (intrinsic, additional, and actual), the additional I_SR resulting from crosstalk reactions exhibits complex behavior owing to its dependence on the opposing electrode. In this study, the effect of the opposing electrode on additional I_SR was examined by measuring the three types of I_SR in Li[Li_1/3Ti_5/3]O₄/Li[Li_0.1Al_0.1Mn_1.8]O₄ cells with different capacity ratios of the positive and negative electrodes. The results indicate that additional I_SR correlates with the weight of the opposing electrode, whereas intrinsic I_SR depends on the weight of each electrode. These findings suggest that additional I_SR is closely related to the amounts of side-reaction products generated at the opposing electrode owing to the intrinsic I_SR. The dependence of crosstalk reactions on the concentration of side-reaction products indicates that these concentrations must be considered to extend battery life by adjusting the actual I_SR.