High-entropy (HE) design has materialized as a transformative paradigm in Na-based electrochemical energy storage, redefining the conventional boundaries of compositional and structural optimization. This review elucidates the fundamental principles governing configurational entropy, lattice disorder, and their impact on phase stability and ion-transport pathways in HE electrodes and solid-state electrolytes. Comparative analysis with traditional analogues reveals that compositional complexity stabilizes metastable frameworks, mitigates Jahn-Teller distortions, and broadens Na+ diffusion networks via entropy-mediated flattening of the free-energy surface, effectively lowering the energy above the convex hull. A critical examination of synthesis and processing methodologies, from solid-state and wet-chemical routes to high-pressure-field-assisted sintering, underlines the complex interplay of precursor chemistry, configurational homogeneity, and resulting electrochemical behavior. HE strategies across electrodes and interfaces are discussed with emphasis on the synergy of structural resilience, redox reversibility, and interfacial stability. Intrinsic stability aspects, including mechanical, air, and thermal stability, are correlated with compositional tuning. The review further identifies persisting challenges in entropy quantification, synthetic reproducibility, and predictive modeling of ion transport in disordered lattices. Finally, it presents perspectives integrating machine learning, density functional theory, and molecular dynamics within high-throughput frameworks to accelerate discovery and establish design-property correlations in complex chemical spaces.

Modern industries are experiencing a dual transition: advancing toward sustainability (Industry 5.0) goals while simultaneously embracing Industry 4.0, characterized by Internet of Things (IoT)-driven smartification. This rapid expansion of interconnected devices is occurring in an era where conventional electronics remain fundamentally unsustainable, with persistent challenges in recycling, metal segregation, and circularity. This disconnect necessitates alternative material and fabrication strategies that can enable scalable sensor deployment without exacerbating environmental burdens. In this review, we analyze recent progress (over the last five years) in low-temperature fabricated polymer-driven sensors, focusing on their relevance for sustainable environmental and health monitoring. Advances across different polymer families and fabrication techniques are systematically examined, with evaluation from both sustainability and scalability perspectives. Special emphasis is placed on how these approaches address limitations of conventional high-temperature, resource-intensive processes and their applicability across sectors such as agriculture, pharmaceuticals, textiles, and chemicals. By examining current literature in light of the dual transition, the review identifies recent trends, outlines knowledge gaps, and highlights pathways for integrating polymer-based sensors into large-scale, environmentally responsible technologies.

Printed circuit boards (PCBs) contain substantial amounts of brominated epoxy resin (BER), which releases hazardous polybrominated dioxins and furans upon thermal treatment. This makes it difficult to recycle PCBs through conventional smelting processes. This study presents a low temperature (similar to 100 degrees C), atmospheric pressure solvothermal process for near-complete removal of BER, achieving similar to 98% debromination of the nonmetallic fraction (NMF) of waste PCBs (WPCBs). The process uses N-methyl-2-pyrrolidone (NMP) as a solvent, which penetrates the polymer matrix, inducing swelling, depolymerization, and cleavage of brominated bonds. The addition of KOH as a catalyst markedly enhances debromination kinetics through secondary reactions that further degrade the BER into phenolic by-products. The NMP solvent is recovered via vacuum distillation and reused without loss of debromination efficiency, establishing a zero liquid discharge system. The solid residue products post filtration and vacuum distillation consist of glass fiber and Br-free resin polymer, which are potentially reusable for secondary applications. The process is demonstrated to be scalable, and a plausible mechanistic pathway for solvothermal debromination is proposed. Overall, this work offers an environmentally sustainable and energy-efficient strategy for bromine removal from end-of-life PCBs, enabling subsequent recycling, metal recovery, and circular material utilization.

Resource recovery from source-separated human urine is a circular economy approach wherein valuable nutrients are recovered and applied for crop growth and food production. Treating urine at the source helps in the reduction of nutrient loads on municipal wastewater treatment plants and plummeting the dependency on mined phosphorus through resource recovery strategies. Systems for separation of urine at source are strongly recommended where nutrients are recovered effectively closer to the source. This paper reviews the (i) significance and opportunities of closed loop sanitation systems, (ii) technical challenges of separating urine at source followed by its collection and storage, (iii) challenges in growth of crops and food production through direct/indirect application of urine to agriculture and (iv) existing and upcoming technologies in the recovery of nutrients, including their limitations. The review, while highlighting the scope of source-separated urine as an untapped resource for nutrient recovery, also identifies the barriers and challenges that must be addressed to enable large scale implementation of such systems.

This study employs a cost-effective chemical co-precipitation method to enhance zinc sulfide (ZnS) for supercapacitor applications through nickel (Ni) doping. ZnS samples with varying Ni concentrations (1

The emergence of high-entropy oxides opens new opportunities for materials design, particularly as promising electrode materials for energy storage and conversion. This study explores a nanocrystalline high-entropy spinel oxide (S-HEO) containing five cations - Al, Cr, Fe, Mn, and Ni in equiatomic amounts. Three bottom-up approaches, namely reverse co-precipitation (RCP), nebulised spray pyrolysis (NSP), and flame spray pyrolysis (FSP), are used to synthesise these oxides to explore their potential as effective bifunctional materials for energy storage and conversion. Phase purity, morphology, and homogeneity are investigated using XRD, TEM, and SEM. Nitrogen absorption studies reveal that the NSP powders possess a relatively large specific surface area. As supercapacitor electrodes, the NSP electrode performed better than the other two electrodes, achieving a specific capacitance of 186 F g- 1 at a current density of 0.3 A g- 1. An asymmetric supercapacitor (ASC) assembled by NSP//activated carbon (AC) exhibits a high energy density of 3 Wh Kg- 1 at a power density of 225.1 W kg- 1. As an electrocatalyst for oxygen evolution reaction (OER), the NSP electrode shows an outstanding overpotential of 298 mV at a current density of 10 mA cm- 2 outperforming the other two electrodes.

Effects of iron impurities on the alkaline hydrogen evolution reaction (HER) for nickel-based electrodes are not fully understood. Iron deposits on the Ni surface can either enhance HER kinetics by increasing surface roughness or act as a protective layer against NiH formation. This work systematically evaluates how different iron concentrations in the electrolyte affect HER activity and durability of polycrystalline Ni in 0.1 M KOH. Initial HER activity differences between 0 and 14 ppm Fez+ species are marginal. However, during 24-h chronopotentiometry tests at i = -10 mA cm-2 (0-3 ppm) cause pronounced deactivation, while higher concentrations (6-14 ppm) maintain more stable operation. Combining structural and electrochemical analyses we link HER overpotential changes to accessible Ni sites, instead of surface roughness. This study shows a critical Fez+ impurity threshold (>= 6 ppm) in the electrolyte to exploit the beneficial effects of iron on HER durability of alkaline water electrolysis.

Heterogeneous carbonaceous resources offer scalable pathways to advanced carbon materials, but their conversion is constrained by variations in composition, mineral matter, structural order, reactivity, and feedstock-preparation burden. Coal-derived graphene oxide (GO) and reduced graphene oxide (rGO) provide a representative case where feedstock selection, beneficiation, oxidation chemistry, product validation, and sustainability assessment are often treated as disconnected steps. Here, coal-to-GO/rGO conversion is used to demonstrate a feedstock-conditioned process design framework for sustainable carbon resource valorisation. The proposed seven-layer framework integrates coal-rank routing, ash and mineralogical triggers, composition- and texture-based process selection, rank-specific pretreatment severity windows, GO/rGO pathway selection, closed-loop product validation, and early-stage sustainability screening. A literature-informed sensitivity matrix and heat map identify variables governing material quality, yield, reagent demand, water use, energy intensity, and environmental performance. The framework is demonstrated through a lignite-to-GO case study incorporating mass and energy balances, reagent inventories, and cradle-to-gate sustainability indicators. The process yielded 0.138 kg GO kg-1 raw lignite, with a cumulative energy demand of 15.5 GJ kg-1 GO, a greenhouse-gas footprint of 2.00 × 103 kg CO2-eq kg-1 GO, and a water footprint of 6412 L kg-1 GO. We further introduce the Feedstock Conditioning Penalty (FCP) as the additional material, energy, chemical, and environmental burden required to convert a heterogeneous carbon resource into a synthesis-ready precursor. In the case study, feedstock conditioning contributed approximately 72% of greenhouse-gas emissions and 89% of electricity demand, identifying upstream upgrading as the dominant sustainability hotspot.

While considering materials for photovoltaics, aluminum ferrite (AlFeO3) has immense technological value because all its constituent elements are earth-abundant. Orthorhombic AlFeO3 has a low bandgap (2 eV). However, the presence of a high concentration of defects can make even low bandgap materials ineffective for photovoltaics. The primary objective of this work was to experimentally determine the kind of intrinsic point defects present in orthorhombic AlFeO3 when it is prepared by the co-precipitation method. By analyzing the results of multiple characterization techniques, we concluded that orthorhombic AlFeO3, when prepared by the co-precipitation method, has a high concentration of aluminum vacancies and oxygen vacancies but a negligible concentration of antisites. The fact that orthorhombic AlFeO3 is likely to have a high concentration of vacancies means that thin films of orthorhombic AlFeO3 should be made by techniques which produce low defect concentrations, if photovoltaic application is the ultimate objective.

The optimization of biomass-derived carbon electrodes is central to advancing sustainable supercapacitors, yet the complex interplay between structure, processing, and performance remains poorly understood. Here, machine learning (ML) and explainable artificial intelligence (XAI) are used to uncover physical insights that guide the rational design of high-performance supercapacitor materials. A curated dataset of 178 literature-reported cases was used for specific capacitance prediction, while 95 cases were analyzed for cyclic stability. Four ML algorithms-linear regression, logistic regression, random forest, and gradient boosting-were evaluated, with gradient boosting achieving the best performance for capacitance prediction (R2 = 0.92, MAE = 20.14) and random forest yielding the highest classification accuracy for stability (F1 = 0.73). SHapley Additive exPlanations (SHAP) analysis identified pore volume, nitrogen doping, and pyrolysis conditions as dominant features governing electrochemical performance. Importantly, the models reveal that shorter pyrolysis times and optimized pore structures enhance capacitance, while excessive surface area compromises long-term stability. Unlike prior ML studies that focus solely on prediction, our integration of XAI bridges computational modeling with physical understanding, providing interpretable design rules for energy storage electrodes. This work establishes a data-driven and interpretable framework for tailoring biomass-derived carbons, thereby advancing the scope of electrochemical power sources.

Oxynitride materials have garnered considerable attention due to their unique properties, making them highly promising for applications in energy storage, catalysis, and other advanced technologies. The term oxynitride has long been used in materials chemistry to describe a wide range of compounds containing both oxygen (O2- ) and nitrogen (N3-) anions. However, its precise definition remains ambiguous-whether it denotes a distinct singlephase compound, a mixture of oxide and nitride phases, or simply a doped material. Among various oxynitride synthesis methods, urea-based approaches stand out for their sustainability, cost-effectiveness, simplicity, and relatively low processing temperatures. These methods provide a unique chemical environment for incorporating nitrogen into oxygen-rich frameworks. In this perspective, we revisit the definition and classification of oxynitrides through the lens of urea-mediated synthesis. Issues such as difficulties in nitrogen incorporation, phase control, and the formation of undesirable byproducts are discussed in the context of their potential benefits. Additionally, it offers insights into how these challenges can be overcome, paving the way for the full realization of urea-assisted oxynitrides in various applications.

Nanostructured γ-Al2O3 was made from boehmite using a soft-chemical process. This involved alkali-controlled co-precipitation and microwave heating at 600°C for crystallization. The study looked into how different alkali types—NaOH, KOH, and LiOH·H2O affected phase changes, microstructure, surface chemistry, optical response, and dielectric properties. XRD and FTIR confirmed that the NaOH-derived sample was phase-pure γ-Al2O3. In contrast, KOH and LiOH·H2O showed secondary aluminate phases and lattice distortion. Raman analysis detected clear tetrahedral and octahedral Al–O modes in the NaOH sample, whereas the others exhibited broader features, indicating greater disorder. TEM images revealed uniform nanocrystalline grains in the NaOH-derived γ-Al2O3, unlike the agglomeration and defects seen in the other samples. XPS results indicate that the dominant bond is Al3+–O2-, with some minor surface species. Dielectric measurements from 0.01 Hz to 1 MHz showed stable permittivity and low loss for the NaOH-derived γ-Al2O3, making it suitable for radio-frequency insulating applications.

In this work, we discuss the fabrication and application of polymer nanocomposite (PNC) films as encapsulants that offer a one-stop solution for heat- and moisture-based degradation issues of silicon solar cells. The PNC encapsulant films were fabricated by dispersing similar to 0.45 wt. % zinc oxide (ZnO) or titanium dioxide (TiO2) nanoparticles into a dilute solution of polyethylene glycol (PEG) in chloroform, followed by addition of polydimethylsiloxane (PDMS) and subsequent curing at 80 degrees C for 20 min. The resulting PNC films of thickness similar to 450 mu m were used as front encapsulants for commercially available mini silicon solar cells. We show that these PNC films enable >80% retention of power conversion efficiency (PCE) after hot-air aging up to 150 degrees C, while the unencapsulated cells retained only similar to 50% of their initial PCE. Moreover, when heated to 60 and 90 degrees C, the surface temperature of PNC-encapsulated cells was similar to 5-8 degrees C lower compared to unencapsulated cells. Furthermore, when subjected to a damp-heat aging test (60 degrees C, 85% relative humidity for 1 week), the PNC-encapsulated cells retained >50% PCE, while the unencapsulated cells retained only similar to 17% PCE. The hydrophobicity and structural integrity of the encapsulant films were preserved despite exposure to high humidity and elevated temperatures. These results highlight the potential of the fabricated PNC films as effective encapsulants to seamlessly mitigate degradation caused by both humidity and heat, thus paving a route to extend the lifespan of silicon photovoltaics deployed in tropical climatic zones.

The transition to sustainable energy highlights the need for efficient green hydrogen production, with ammonia emerging as a promising hydrogen carrier due to its transport and storage capabilities. The US Department of Energy has recognized it as the most pipeline-compatible option for large scale transport distribution. Overcoming the sluggish kinetics of the ammonia oxidation reaction (AOR) remains a crucial challenge for advancing this technology. This study reports a bifunctional Ni-based catalyst, focusing on the transformation from nickel oxide (NiO) to nickel oxynitride (NiOxNy), synthesized by the soft urea method for ammonia splitting. Nitrogen incorporation into the NiO lattice induces defects, leading to a band gap narrowing in NiOxNy (2.15 eV) compared to pristine NiO (3.8 eV), as evidenced by the Tauc plot derived from UV-vis absorption spectroscopy. The presence of active sites, which play a crucial role in determining catalytic activity, was found to be 0.611 mmol/g(catalyst). The NiOxNy exhibits superior performance compared to NiO, metallic Ni, and standard RuO2, with an AOR overpotential of 1.357 V vs SHE and a Tafel slope of 54.14 mV dec(-1) at 10 mA cm(-2). For the hydrogen evolution reaction (HER), it also outperforms the benchmark Pt/C, exhibiting a lower overpotential of 151 mV vs SHE and a Tafel slope of 93.55 mV dec(-1). Additionally, the catalyst demonstrates better long-term stability as a bifunctional catalyst for 12 h. These finding highlights that nitrogen-induced structural modifications improve electrical conductivity and generate defect-rich surfaces, facilitating efficient hydrogen adsorption and desorption, thereby advancing hydrogen production technologies.

Materials containing organic and inorganic mercury compounds are hazardous once diffused into air, water, or soil. Current methodologies for the simultaneous detection and detoxification of Hg(II) from animal tissues, aqueous samples, and plant cells are limited and require further research. Recently, an exceptionally selective fluorescent sensor (PyDMSA) has been reported for this purpose. It is prepared from a cationic dye, Pyronin Y (Py), and meso-2,3-dimercaptosuccinic acid (DMSA). This article presents the chemistry of this fluorescent sensor from a theoretical standpoint, using Density Functional Theory (DFT) with the level of theory, PBE1PBE/def2tzvp. The thermochemistry of reactions leading to the dissociation of PyDMSA and complex formation with Hg(II) in tissues are analysed computationally. The Gibbs free energies of reaction indicate spontaneity. The stability constants of the complexes [Hg-(II)(DMSA)] and [Hg-(II)(DMSA)(2)](2-) indicate their stability in aqueous medium. The bond dissociation energies of the -C-S- bond in PyDMSA and the -S-H bond in DMSA support the experimental observation of weaker bonds and dissociation. Given the need for further research on protocols for simultaneous detection and detoxification of Hg(II) and similar toxic metals from biological samples, both experimental and computational studies are beneficial for researchers designing molecular sensors for hazardous metals. [GRAPHICS] .

Copper is an essential trace element for human health, and a key micronutrient for plants. However, excess of copper can pose risks to environment and human health. Therefore, tools for quantitative detection of copper as well as other heavy metals are useful in various settings. Such tools are crucial for ensuring safe water access and monitoring wastewater treatment. Here, we report the development of a copper (Cu2+) sensor that is capable of operating in aqueous media over a wide concentration window between 1 nM and 8 mM within an error of 10%. The sensor test strip was fabricated by drop casting the polymer poly(3,4-ethylene dioxythiophene)-poly(styrene sulfonate) (PEDOT:PSS) on glass substrate. Subsequently, the PEDOT:PSS test strips were dip coated in Cu2+ containing aqueous solution, and analyzed using Fourier transform infrared (FTIR) spectroscopy. The area under relevant portions of the FTIR spectra were computed to arrive at calibration curves, which serve as the basis for sensing. The polymer-metal interaction that facilitates sensing is discussed in light of Pearson's hard soft acid base (HSAB) theory. The results provide a foundation for fabrication of low-cost, targeted detection systems for heavy metal ions over a wide concentration range.

This study introduces a novel PDMS/Au/PDMS multi-layered thin-film composite designed for infrared (IR) filtering and hydrophobic coating applications, fabricated using spin coating and sputtering techniques. The composite, with an approximate thickness of 30 mu m, exhibits a surface roughness that enhances near-infrared (NIR) reflectance through diffuse scattering, achieving a reflectance of up to similar to 60%, while maintaining visible light transmission of approximately 70%. The choice of gold as the intermediate layer in this study is motivated by its optical property of surface plasmon resonance, which significantly contributes to the material's reflective characteristics in the NIR spectrum. This unique combination of NIR reflectivity and visible light transparency makes the film ideal for applications like solar cell encapsulation, with the potential to boost photon absorption while reducing heat buildup. Additionally, this composite film shows promise as a coating for greenhouse windows and for thermal management in electronic devices, representing a significant advancement in multifunctional, energy-efficient materials.