Engineered Cellulose: A Multifunctional Platform for Next‐Generation Sustainable Environmental Technologies

Biochar, a porous carbonaceous material produced from biomass pyrolysis under limited oxygen, has emerged as a promising material for environmental remediation due to its stability, adsorption capacity, and potential for carbon sequestration. Though raw or unmodified biochar often exhibits limited surface functionality, low surface area, and poor affinity for specific contaminants, its effectiveness in practical applications is restricted. Various modification techniques have been developed to address these limitations, including physical activation, chemical functionalization, and surface doping with metals. Among these, iron-modified biochar (Fe-BC) has attracted considerable attention due to the unique redox properties of iron and its strong binding affinity for anions and organic pollutants. Fe-BC is typically synthesized through impregnation, co-pyrolysis with iron salts, or post-pyrolysis treatment. These modifications enhance the surface area and porosity and introduce reactive sites that significantly improve the sorption of phosphate, arsenic, heavy metals, and dyes from wastewater, as well as facilitate catalytic reactions such as Fenton-like oxidation. Recent studies have demonstrated the multifunctionality of Fe-BC in wastewater treatment and soil remediation, as well as in agriculture as a slow-release nutrient carrier. Moreover, novel synthesis approaches using green chemistry principles and low-cost iron precursors have made Fe-BC more sustainable and scalable. Despite its potential, challenges remain regarding the long-term stability of leaching iron, regeneration, and environmental risks. This review provides a comprehensive analysis of current modification strategies for biochar with a focused evaluation of Fe-BC, including synthesis methods, physicochemical properties, contaminant removal mechanisms, and practical applications. Future perspectives are discussed to guide research toward optimizing Fe-BC for the circular economy and sustainable environmental technologies.

The advent of electric automobiles has garnered great interest in multifunctional electrochemical energy storage architectures which have the potential to store and release energy on demand while simultaneously being subjected to static or dynamic load conditions. At the forefront of these technologies are energy storage integrated fiber reinforced composites which promise substantial benefits to both mechanical as well as electrochemical performance. In this context, the design of interfaces that dually store energy and maintain composite mechanical integrity under load is of critical importance. Here, I will illustrate our systematic efforts on the development of multifunctional structural energy storage composites starting with CNTs grown on lightweight stainless steel meshes and incorporation of these materials into energy storing composite laminates where we simultaneously test mechanical and electrochemical performance. To further augment the energy storing capability of the carbon nanotubes, we electro-deposit ultrafast redox active pseudocapacitive nickel oxide and iron oxide onto the CNTs to fabricate fiber reinforced nickel-iron asymmetric redox pseudocapacitiors or nickel-iron ‘ultra-battery’ composites. Overall, composites showcase high power densities of 10 kWh/kgActive and comparable energy densities of 20 Wh/kgActive. Furthermore, these multifunctional composites demonstrate good mechanical (tensile, flexural and load impact) behavior while simultaneously exhibiting stable charge/discharge performance during in-situ mechano-electrochemical measurements. These results thus forge a path toward practical multifunctional composites by combining (1) in-situ mechano-electrochemical testing to assess structural energy storage performance, (2) effective reinforcements and prevent failure at structural interfaces, and (3) redox-active materials processed to augment energy density. Overall, these results provide new insights and creates a framework for developing such multifunctional energy storage architectures for a multitude of load-bearing applications.

All‐solid‐state batteries (ASSBs) are a pivotal advancement for next‐generation energy storage, addressing the safety and energy density limitations of conventional lithium‐ion systems. Among various solid‐state electrolytes (SSEs), halide‐based SSEs have emerged as particularly promising candidates due to their unique combination of high ionic conductivity (0.1–10 mS cm −1 ), exceptional electrochemical stability (>4.5 V), and favorable mechanical properties. In contrast to polymer SSEs (limited by low ionic conductivity), oxide SSEs (requiring energy‐intensive processing), and sulfide SSEs (exhibiting moisture sensitivity and high cost), halide SSEs offer a more balanced performance profile, making them highly suitable for commercial applications. This perspective highlights halide SSEs as a key enabler for the commercialization of ASSBs, not only due to their superior material properties but also because of their advantages in scalable synthesis and industrial compatibility. Specifically, halide SSEs can be processed at room temperatures and pressures, and exhibit better interfacial compatibility with high‐voltage cathodes. These attributes significantly simplify the transition from lab‐scale research to pilot‐scale production, reducing both energy consumption and manufacturing complexity. Furthermore, a unified lab‐to‐pilot framework is proposed that integrates fundamental electrochemistry with scalable engineering practices for halide SSEs. A 2D evaluation system is also introduced to guide the selection of optimal application scenarios for ASSBs. By addressing critical challenges such as moisture sensitivity, interfacial degradation, and mechanical brittleness, halide SSEs are positioned as the most manufacturable pathway toward the commercialization of ASSBs for electric vehicles and grid‐scale storage. This work is the first to provide a comprehensive strategy perspective on halide‐based ASSB pilot lines, offering practical insights into material selection, process optimization, and industrial scalability.

The introduction of electric vehicles (EVs) has posed many technical challenges to the automotive industry; in particular, the state-of-the-art lithium-ion (Li-ion) batteries add massive weight to vehicles both in the form of battery weight and supporting systems, immensely hindering vehicle performance and efficiency. A primary source of this challenge is that the battery packs serve only one purpose – energy storage, as current EV batteries do not carry loads or absorb collision impact energy. Recently introduced by the authors, a hybrid energy storage design, called the Multifunctional Energy Storage Composites (MESC), possesses the unique feature of simultaneously carrying tremendous structural loads and providing energy-storage capabilities (1-3). It has been demonstrated that the concept potentially leads to significant weight and volume savings in electric vehicle and system designs. In brief, the MESC involves a unique integration technique for embedding Li-ion battery materials in structural carbon-fiber-reinforced-polymers (CFRP). The crux of the multifunctional design is the incorporation of three-dimensionally interlocking “rivets” (1-3). The electrode layers, which make up the battery stack, contain a rectangular array of perforations (with diameter on the order of millimeters), instead of being solid, continuous, planar films. The perforations in each layer of the stack line up to fit the interlocking rivets, which three-dimensionally interlock the electrodes and rigidly anchor onto the stiff CFRP faceplates. The interlocking rivets exploit the intrinsic mechanical properties of the Li-ion battery electrodes, allowing them to carry mechanical loads. Despite the non-conventional cell construction, the MESC has demonstrated cycling and cycle-life performance tantamount to commercial pouch cells, with similar mechanical load carrying capabilities to automotive structural materials (2). Even though the rivets are indispensable in the MESC design and offer immense mechanical benefits, they present a slight electrochemical challenge. The presence of the perforations influences the current flow path, current density distribution, and depth of discharge (DoD) uniformity. Therefore, in this work, special attention is given to the numerical modelling and optimization of current density distribution in the electrodes, with the presence of a perforation array. Standard non-perforated graphite/NMC pouch cells are used to determine the DoD dependency of the intrinsic open-circuit voltage, electrochemical conductance, and resistance. The governing equations for charge conservation, polarization, and current density are solved numerically in COMSOL simulation (4-6). The perforations are included as boundary conditions on the electrode domains. The model is parameterized to capture various geometrically feasible perforation patterns, array densities, and diameters. Under different constant-current profiles, the non-uniformity of current density distribution and DoD is quantified. The increase in cell impedance, due to the local constriction and spreading of electrical current, is also evaluated. Complete functional relationships between perforation parameters (e.g. pattern, density, and hole diameter) and the electrochemical performance (current density distribution, DoD distribution, cell impedance, etc.) are established. Counter-intuitively, our results confirm minimal electrochemical impact in MESC cells with current path disruption sufficient for mechanical stabilization. Compared to unperforated cells of the same dimensions, less than a 10% increase in non-uniformity of current distribution and less than a 5% increase in cell impedance are observed. Beyond these indicative results, the model provides meaningful physical insights into the current flow path around the holes, as well as near the current collector tabs. Together, these allow the MSEC electrode design to be optimized in the electrochemical-mechanical tradeoff. Additionally, towards a broader context, it is believed this study will shed light upon electrode design and the optimization of conventional high-energy, high-power Li-ion batteries. To this end, a first step has already been taken to generalize the model and employ advanced optimization schemes e.g. genetic algorithms (GA). References P. Ladpli, R. Nardari and F.-K. Chang, Multifunctional Energy Storage Composites, WO patent application 2016127122, published 2016-08-11.P. Ladpli, R. Nardari, R. Rewari, H. Liu, M. Slater, K. Kepler, Y. Wang, F. Kopsaftopoulos and F.-K. Chang, Multifunctional Energy Storage Composites: Design, Fabrication, and Experimental Characterization, in ASME 2016 Energy Storage Forum, Charlotte, NC (2016).P. Ladpli, R. Nardari, Y. Wang, P. A. Hernandez-Gallegos, R. Rewari, H. T. Kuo, F. Kopsaftopoulos, K. D. Kepler, H. A. Lopez and F. Chang, Multifunctional Energy Storage Composites for SHM Distributed Sensor Networks, in International Workshop on Structural Health Monitoring 2015, Stanford, CA (2015).U. S. Kim, C. B. Shin and C.-S. Kim, Journal of Power Sources, 189, 841 (2009).K. H. Kwon, C. B. Shin, T. H. Kang and C.-S. Kim, Journal of Power Sources, 163, 151 (2006).J. Newman and W. Tiedemann, Journal of The Electrochemical Society, 140, 1961 (1993). Figure 1

The use of portable air cleaning devices in residential settings has been steadily growing over the last 10 years. Three out of every 10 households now contain a portable air cleaning device. This increased use of air cleaners is accompanied by, if not influenced by, a fundamental belief by consumers that the air cleaners are providing an improved indoor air environment. However, there is a wide variation in the performance of air cleaners that is dependent on the specific air cleaner design and various indoor factors. The most widely used method in the United States to assess the performance of new air cleaners is the procedure described in the American National Standards Institute (ANSI)/Association of Home Appliance Manufacturers (AHAM) AC-1-2002. This method describes both the test conditions and the testing protocol. The protocol yields a performance metric that is based on the measured decay rate of contaminant concentrations with the air cleaner operating compared with the measured decay rate with the air cleaner turned off. The resulting metric, the clean air delivery rate (CADR), permits both an intercomparison of performance among various air cleaners and a comparison of air cleaner operation to other contaminant removal processes. In this article, we comment on the testing process, discuss its applicability to various contaminants, and evaluate the resulting performance metrics for effective air cleaning.

Multifunctional composite as a structural supercapacitor and self-sensing sensor using NiCo2O4 nanowires and ionic liquid

Structural batteries have emerged as a promising alternative to address the limitations inherent in conventional battery technologies. They offer the potential to integrate energy storage functionalities into stationary constructions as well as mobile vehicles/planes. The development of multifunctional composites presents an effective avenue to realize the structural plus concept, thereby mitigating inert weight while enhancing energy storage performance beyond the material level, extending to cell‐ and system‐level attributes. Specifically, multifunctional composites within structural batteries can serve the dual roles of functional composite electrodes for charge storage and structural composites for mechanical load‐bearing. However, the implementation of these multifunctional composites faces a notable challenge in simultaneously realizing mechanical properties and energy storage performance due to the unstable interfaces. In this review, we first introduce recent research developments pertaining to electrodes, electrolytes, separators, and interface engineering, all tailored to structure plus composites for structure batteries. Then, we summarize the mechanical and electrochemical characterizations in this context. We also discuss the reinforced multifunctional composites for different structures and battery configurations and conclude with a perspective on future opportunities. The knowledge synthesized in this review contributes to the realization of efficient and durable energy storage systems seamlessly integrated into structural components.

This study reviews the importance of resistant starch (RS) as the polymer of choice for biodegradable food packaging and highlights the RS types and modification methods for developing RS from native starch (NS). NS is used in packaging because of its vast availability, low cost and film forming capacity. However, application of starch is restricted due to its high moisture sensitivity and hydrophilic nature. The modification of NS into RS improves the film forming characteristics and extends the applications of starch into the formulation of packaging. The starch is blended with other bio-based polymers such as guar, konjac glucomannan, carrageenan, chitosan, xanthan gum and gelatin as well as active ingredients such as nanoparticles (NPs), plant extracts and essential oils to develop hybrid biodegradable packaging with reduced water vapor permeability (WVP), low gas transmission, enhanced antimicrobial activity and mechanical properties. Hybrid RS based active packaging is well known for its better film forming properties, crystalline structures, enhanced tensile strength, water resistance and thermal properties. This review concludes that RS, due to its better film forming ability and stability, can be utilized as polymer of choice in the formulation of biodegradable packaging.

As a promising lightweight multifunctional material, carbon fiber structural battery composites have great potentials to enable longer service life and operating distance for the rapidly increasing mobile electric technologies. While simultaneously carrying mechanical loads and storing electrical energy, the developed multifunctional composites can achieve “massless” energy storage and further extend to sensing and energy harvesting for self-powered structural health monitoring. However, it is still very challenging to predict the state-of-health of structural battery composites due to a lack of understanding of underlying coupled mechanical-electrochemical phenomena during operation. In this study, we first use a novel 3D printing method to fabricate and tailor microstructure of the multifunctional carbon fiber composites. With an optimal electrode layer thickness of 0.4 mm, the stable specific capacity at 1C reaches over 80% of the theoretical capacity of the electrode active materials (lithium iron phosphate) with an average energy density of 152 Wh/kg observed. The corresponding flexural modulus and flexural strength are 8.7 GPa and 69.6 MPa, respectively. The state-of-health of 3D printed structural battery composites under electrochemical cycling and external mechanical loadings are also investigated. The mechanical performance is not affected by the electrochemical charge-discharge processes. The structural battery composites under three-point bending testing show good capacity retention with rapid degradation of electrochemical performance observed near fracture point. The findings from this study not only provide insights for monitoring the state-of-health of structural battery but also show mechanical-electrochemical coupling as a potential way of self-powered structural health monitoring through the 3D printed multifunctional composites.

The performance of gaseous air cleaners for commercial and residential buildings has typically been evaluated using test protocols developed for a controlled laboratory chamber or a test duct. It is currently unknown how laboratory measurements relate to the actual performance of an air cleaner installed in a real building. However, to date, there are no air cleaner field test protocols available, thereby limiting the existing field data. The National Institute of Standards and Technology (NIST) has conducted a series of experiments to support test procedure development for evaluating the installed performance of gaseous air cleaning equipment, as well as metrics for characterizing field performance. To date, over 100 experiments have been completed, of which 23 portable air cleaner experiments and 6 in-duct air cleaner experiments are described in this paper. Tests were conducted in a finished three-bedroom/two-bathroom manufactured house equipped with several gas chromatographs to semi-continuously measure air change rates and volatile organic compound concentrations. Experimental variables included air cleaner location, isolation of zones by closing doors, and contaminant source location. For each experiment, air cleaner removal of decane was directly measured using the air cleaner inlet and outlet concentrations, as well as with mass balance analyses using measured room concentrations. With a verified mass balance model, a field performance metric was developed to compare installed whole-building performance to the performance predicted by a laboratory result. The results provide insight into the protocols and metrics that might prove useful for characterizing the field performance of air cleaners as well as the impact of air cleaner removal on zonal concentration levels in a variety of situations.

MXenes have emerged as versatile materials due to their distinct combination of metallic conductivity, hydrophilicity, mechanical flexibility, and tunable surface chemistry. These properties have enabled their application across various fields such as energy storage, catalysis, and biomedical devices, with thermoelectric energy conversion acquiring attention. MXene distinguishes for its exceptional hardness, high melting point, and electrical conductivity, making it a strong candidate for thermoelectric applications, particularly under high temperature factors. This review provides an overview of the latest advances in the thermoelectric performance of MXenes. We discuss strategies such as doping, hetero structure formation, and defect engineering that have been used to improve parameters, including the Seebeck coefficient and to suppress lattice thermal conductivity, thereby improving the figure of merit (ZT). Challenges related to synthesis scalability, material stability, and the undermine between electrical and thermal transport are crucially evaluated. This study emphasizes directions for the future, including the evaluation of hybrid thermoelectric device systems and environmentally sustainable synthesis methods, to facilitate the practical deployment of MXene-based thermoelectric devices. • A dedicated focus on thermoelectric performance metrics (Seebeck coefficient, electrical/thermal conductivity, power factor, and ZT). • Integration of experimental and computational insights, including band structure engineering and carrier transport mechanisms. • Comparative evaluation of prominent MXene systems such as V₂C, Ti₃C₂, Nb₂C, and Mo₂C, highlighting composition–property relationships. • Extensive use of schematics, comparative tables, and performance maps to enhance accessibility for a broad energy research audience.

The simultaneous need for high specific mechanical properties and thermal energy storage (TES) function, present in several applications (e.g., electric vehicles), can be effectively addressed by multifunctional polymer-matrix composites containing a reinforcing agent and a phase change material (PCM). The PCMs generally decrease the mechanical properties of the host structural composites, but a multifunctional composite can still be beneficial in terms of mass saving, compared to two monofunctional units performing the structural and heat management functions individually. To quantify any possible advantages, this paper proposes an approach that determines the conditions for an effective mass saving at the system level and ranks the investigated structural TES composites with a parameter called multifunctional efficiency. It is found that the potential mass saving is higher when the volume fraction of the reinforcement is kept constant also when the PCM fraction increases or when the single phases (reinforcement, PCM) are themselves multifunctional.

The global energy transition and the implementation of carbon capture, utilization, and storage (CCUS) strategies require energy-efficient and scalable CO2 separation technologies. Mixed-matrix membranes (MMMs), combining polymer matrices with functional inorganic or hybrid nanofillers, have emerged as advanced separation platforms capable of surpassing the conventional permeability–selectivity trade-off observed in neat polymer membranes. This review critically evaluates recent developments in modern hybrid membranes for CO2 separation from synthetic and industrial gas mixtures, including CO2/N2 (flue gas), CO2/CH4 (natural gas and biogas upgrading), and syngas systems. Particular emphasis is placed on MMMs incorporating covalent organic frameworks (COFs), metal–organic frameworks (MOFs), graphene oxide (GO), MXenes, transition metal dichalcogenides (TMDs), carbon nanotubes (CNTs), g-C3N4, layered double hydroxides (LDH), zeolites, metal oxides, and magnetic nanoparticles. Reported performance ranges include CO2 permeability (PCO2) typically between 100 and 800 Barrer, CO2/N2 selectivity up to 319, and CO2/CH4 selectivity up to 249, depending on filler chemistry, loading, and interfacial compatibility. The mechanisms governing gas transport—molecular sieving, selective adsorption, facilitated transport, and diffusion-pathway engineering—are systematically discussed. Key challenges addressed include filler dispersion, polymer–filler interfacial defects, physical aging, moisture sensitivity, oxidation (particularly in MXenes), and scalability toward industrial membrane modules. Future perspectives focus on sub-nanometer pore engineering, surface functionalization to enhance CO2 affinity, controlled alignment of 2D nanosheets to promote directional transport, multifunctional core–shell and hollow structures, and the integration of computational modeling and machine learning for accelerated material design. Modern hybrid MMMs are identified as strategically important materials enabling high-efficiency CO2 separation processes aligned with decarbonization and energy transition objectives.

Multifunctional sandwich composites containing embedded lithium-ion polymer batteries under bending loads

The dramatic environmental pollution and energy shortages have spurred internationally unprecedented interest in developing new energy technologies. Supercapacitors have emerged as a new class of green electrochemical devices for energy conversion and storage and are promising candidates for extensive applications. As a key component of supercapacitors, electrode materials are a crucial factor to the electrochemical performance based on its properties including surface area, pore structure, conductivity and surface functionalization. The well-designed synthesis strategies and conditions are usually fatal to tailor four mentioned properties. Due to the advantages of low cost, high specific surface area and conductivity, controllable microstructure, easy surface functionalization, remarkable chemical stability and outstanding electrolyte ion accessibility, porous carbon materials tailored through well-designed synthesis strategies and conditions, exhibit high energy density and power density as well as superb electrochemical cycling stability. In this review, we firstly provide a brief description of energy storage mechanisms for different types of electrode materials, followed by a comprehensive overview of recent advances in development of different carbon-based materials with activated carbon, carbon aerogels, carbon fiber, mesoporous carbon, carbon nanotube and graphene. Then we state the key parameters to evaluate the electrochemical properties, such as specific capacitance, energy density and power density, and also discuss the relationship between the influence parameters (e.g. surface area, pore structure, conductivity, and surface properties) and enhanced performances. Further, according to the research work of our group, we present a summary on the design, synthesis and applications in energy conversion and storage based on porous carbon materials, including carbons with different pore distributions (hierarchical porous carbon, porous carbon sphere, ultramicroporous carbon), functionalized porous carbon and porous carbon composite materials. In terms of carbons with different pore distributions, we list some characteristic synthetic methods (e.g. the self-template strategy for banana-peel-derived hierarchical porous carbon foams, the seeded synthetic strategy for phenolic-resin-derived porous carbon nanospheres and the solvothermal method for phloroglucinol-terephthaldehyde-derived ultramicroporous carbon nanoparticles), which can be concluded that micropores (especially ultramicropores) are electrochemically available for electrolyte ions because the solvation shell is squeezed through the pores less than the solvated ion size and such distortion reduces distance between the electrode surface and the ion center, while mesopores offer highly efficient pore channels for ion penetration and transport. In terms of functionalized porous carbon, we adopt the in situ synthesis approach to prepare nitrogen-doped carbons ( e.g. poly(1, 5-diaminonapthalene)-derived nitrogen-containing carbon microspheres and phenylenediamine-terephthalaldehyde-derived nitrogen-functionalized microporous carbon nanoparticles), which demonstrate that heteroatom doping, on the one hand, increases the surface wettability in the aqueous electrolyte to improve the mass transfer efficiency, and on the other hand, endows additional psedocapacitance for the electrode. In terms of porous carbon composite materials, we combine carbon-based materials with pseudocapacitive metal oxides (e.g. NiO and MnO2) for achieving high-performance supercapacitors, which is a wise choice to increase the energy density without sacrificing the high power capability. These strategies and methods provide new ideas to simple and highly efficient design of porous carbon materials and may be extendable to other systems such as metal or metal oxide materials. Additionally, the future trend of carbon based electrode materials for energy conversion and storage device is discussed. There are extensive applications outside the area of high-rate electrochemical energy storage, such as drug delivery, photonic crystals, adsorption and separation, and catalysis.