Flexible MXene/Nanocellulose Composite Aerogel Film with Cellular Structure for Electromagnetic Interference Shielding and Photothermal Conversion

Cellulose-Based Electromagnetic Functional Aerogels: Mechanism, Fabrication, Structural Design, and Application

Electromagnetic functional materials offer a promising solution to reduce impacts from electromagnetic pollution and interference, such as digital communications, national defenses, and military fields. Cellulose-based aerogels, featured with their hierarchical porous structure, high specific surface area, and surface activity, can be engineered to possess electromagnetic wave shielding and absorption capabilities through structural regulation, composition optimization, and material functionalization. Moreover, these cellulose-based aerogels exhibit remarkable renewability and biocompatibility, highlighting their significant potential in the field of electromagnetic functional materials. In this review, we stigmatically overview the state-of-the-art of cellulosic electromagnetic functional aerogels, which begins with elucidating the mechanisms behind electromagnetic interference shielding and microwave absorption. The material design based on the physical and chemical characteristics of cellulose aerogels is discussed. Furthermore, the hierarchical design strategies of the cellulosic electromagnetic functional aerogels are reviewed including macro-structures, micro/nanostructures, and supramolecular structures. Multifunctional applications of cellulose electromagnetic functional aerogels are presented, such as infrared and radar stealth materials, intelligent responsive electromagnetic devices, and radiation protection equipment. Finally, an up-to-date summary and an outlook on developing the cellulose-based electromagnetic functional aerogels are provided in the fields of electromagnetic interference shielding and microwave absorption, as well as outlining future research perspectives.

Supramolecular room-temperature flowable lignin (RTFL)/MXene for sustainable coatings

Thermoelectric coatings with high biomass content, excellent storage stability, and solvent-free curing capabilities are highly desirable yet challenging. In this study, we demonstrate that supramolecular room-temperature flowable lignin (RTFL) was introduced as an effective carrier for the two-dimensional conductive material MXene, facilitating the development of supramolecular sustainable coatings. Lignosulfonic acid (LA) and polymerizable quaternary ammonium salt monomers were successfully utilized to synthesize the RTFL with ultra-low glass transition temperatures (-67--38 °C) using a deep eutectic strategy, with lignin content reaching up to 50 wt% without relying on traditional solvents. The RTFL demonstrated, serving as a macromolecular solvent, effectively dispersing and stabilizing MXene while preventing long-term oxidation. When directly coated onto various substrates and subsequently subjected to rapid photopolymerization, the RTFL/MXene coating exhibited remarkable photo-thermal-electric conversion properties. These features meet the requirements of various electrical applications, including Stirling engines and battery charging lamps. This supramolecular approach offers a pathway for developing high biomass content coatings suitable for environmental and energy-related applications.

A Review on MXene/Nanocellulose Composites: Toward Wearable Multifunctional Electromagnetic Interference Shielding Application

With the rapid development of mobile communication technology and wearable electronic devices, the electromagnetic radiation generated by high-frequency information exchange inevitably threatens human health, so high-performance wearable electromagnetic interference (EMI) shielding materials are urgently needed. The 2D nanomaterial MXene exhibits superior EMI shielding performance owing to its high conductivity, however, its mechanical properties are limited due to the high porosity between MXene nanosheets. In recent years, it has been reported that by introducing natural nanocellulose as an organic framework, the EMI shielding and mechanical properties of MXene/nanocellulose composites can be synergically improved, which are expected to be widely used in wearable multifunctional shielding devices. In this review, the electromagnetic wave (EMW) attenuation mechanism of EMI shielding materials is briefly introduced, and the latest progress of MXene/nanocellulose composites in wearable multifunctional EMI shielding applications is comprehensively reviewed, wherein the advantages and disadvantages of different preparation methods and various types of composites are summarized. Finally, the challenges and perspectives are discussed, regarding the performance improvement, the performance control mechanism, and the large-scale production of MXene/nanocellulose composites. This review can provide guidance on the design of flexible MXene/nanocellulose composites for multifunctional electromagnetic protection applications in the future intelligent wearable field.

Advanced functional materials based on nanocellulose/Mxene: A review

The escalating need for a sustainable future has driven the advancement of renewable functional materials. Nanocellulose, derived from the abundant natural biopolymer cellulose, demonstrates noteworthy characteristics, including high surface area, crystallinity, mechanical strength, and modifiable chemistry. When combined with two-dimensional (2D) graphitic materials, nanocellulose can generate sophisticated hybrid materials with diverse applications as building blocks, carriers, scaffolds, and reinforcing constituents. This review highlights the progress of research on advanced functional materials based on the integration of nanocellulose, a versatile biopolymer with tailorable properties, and MXenes, a new class of 2D transition metal carbides/nitrides known for their excellent conductivity, mechanical strength, and large surface area. By addressing the challenges and envisioning future prospects, this review underscores the burgeoning opportunities inherent in MXene/nanocellulose composites, heralding a sustainable frontier in the field of materials science.

Petal-Shaped Graphene Porous Films with Enhanced Absorption-Dominated Electromagnetic Shielding Performance and Mechanical Properties

The absorption-dominated graphene porous materials, considered ideal for mitigating electromagnetic pollution, encounter challenges related to intricate structural design. Herein, petal-like graphene porous films with dendritic-like and honeycomb-like pores are prepared by controlling the phase inversion process. The theoretical simulation and experimental results show that PVP K30 modified on the graphene surface via van der Waals interactions promotes graphene to be uniformly enriched on the pore walls. Benefiting from the regulation of graphene distribution and the construction of honeycomb pore structure, when 15 wt % graphene is added, the porous film exhibits absorption-dominated electromagnetic shielding performance, compared with the absence of PVP K30 modification. The total electromagnetic shielding effectiveness is 24.1 dB, an increase of 170%; the electromagnetic reflection coefficient reduces to 2.82 dB; The thermal conductivity reaches 1.1 W/(m K), representing a 104% increase. In addition, the porous film exhibits improved mechanical properties, the tensile strength increases to 6.9 MPa, and the elongation at break increases by 131%. The method adopted in this paper to control the enrichment of graphene in the pore walls during the preparation of honeycomb porous films by the phase inversion method can avoid the agglomeration of graphene and improve the overall performance of the porous graphene porous films.

Hollow Metal-Organic Framework/MXene/Nanocellulose Composite Films for Giga/Terahertz Electromagnetic Shielding and Photothermal Conversion

With the continuous advancement of communication technology, the escalating demand for electromagnetic shielding interference (EMI) materials with multifunctional and wideband EMI performance has become urgent. Controlling the electrical and magnetic components and designing the EMI material structure have attracted extensive interest, but remain a huge challenge. Herein, we reported the alternating electromagnetic structure composite films composed of hollow metal-organic frameworks/layered MXene/nanocellulose (HMN) by alternating vacuum-assisted filtration process. The HMN composite films exhibit excellent EMI shielding effectiveness performance in the GHz frequency (66.8 dB at Ka-band) and THz frequency (114.6 dB at 0.1-4.0 THz). Besides, the HMN composite films also exhibit a high reflection loss of 39.7 dB at 0.7 THz with an effective absorption bandwidth up to 2.1 THz. Moreover, HMN composite films show remarkable photothermal conversion performance, which can reach 104.6 °C under 2.0 Sun and 235.4 °C under 0.8 W cm-2, respectively. The unique micro- and macro-structural design structures will absorb more incident electromagnetic waves via interfacial polarization/multiple scattering and produce more heat energy via the local surface plasmon resonance effect. These features make the HMN composite film a promising candidate for advanced EMI devices for future 6G communication and the protection of electronic equipment in cold environments.

Flexible Sandwich-Shaped Cellulose Nanocrystals/Silver Nanowires/MXene Films Exhibit Efficient Electromagnetic-Shielding Interference Performance

The electromagnetic pollution problem is becoming increasingly serious due to the speedy advance of electronic communication devices. There are broad application prospects for the development of flexible, wearable composite films with high electromagnetic interference (EMI)-shielding performance. The MX@AC composite films were prepared from MXene, silver nanowires (AgNWs) and cellulose nanocrystals (CNCs) with a sandwich structure. Benefiting from the upper and lower frame structure formed by winding 1D AgNWs and CNC, the tensile strength of the MX@AC was improved to 35 MPa (12.5 wt% CNC content) from 4 MPa (0 wt% CNC content). The high conductivity of MXene and AgNWs resulted in the MX@AC composite film conductivity up to 90,670 S/m, EMI SE for 90 dB, as well as SSE/t up to 7797 dB cm2 g-1. And the MX@AC composite film was tested for practical application, showing that it can effectively isolate electromagnetic waves in practical application.