Applied Mathematics and Computation

ABSTRACTFunctionalities of materials tightly relate to the atomic and electronic structures, the coupling between which through lattice and charge gives birth to thermoelectricity, enabling a direct heat‐electricity conversion. Booming wearable electronics nowadays urgently demand thermoelectric film generators as self‐powered units using body and environment heats, of which highly recoverable deformability and power are the core challenges. This indicates the great importance of elasticity since a plastic deformation otherwise actuates lattice slips to unsecure both thermoelectricity and recoverability. It is illustrated in this work texturization and dislocations for enhancing elasticity in cold‐rolled constantan foils, a metal thermoelectric enabling one of the highest power outputs near room temperature for deformable wearables. The device can work in a purely elastic region, to secure orders of magnitude improvement in recoverable bendability with an extraordinary specific power density, at a bending radius down to 5 mm fitting the curvature of an adult's little finger. This work delivers a strategy for bringing robust deformability to thermoelectricity for powering wearable electronics.

ABSTRACTAdvanced nanofibrous materials with excellent performance and functional integration is highly desired for developing emerging wearable electronics. In this work, carbon quantum dots/poly(vinylidene fluoride) (CDs/PVDF) based composite nanofibrous material is proposed and acts as a highly negative material to boost output performance for triboelectric nanogenerators (TENGs). The nanometer‐sized and surface‐functionalized CDs acting as nucleating inducers facilitate the polarized β‐phase transition of PVDF polymer. The more negative surface charge density of CDs/PVDF nanofibrous membrane is generated through the polarized β‐phase PVDF, thereby leading to a larger electrostatic potential difference to enhance charge transfer. Besides the decreased beaded defects, more uniform morphology fibers are yielded to improve the effective contact surface area. Moreover, the CDs/PVDF composite nanofibers demonstrate the unique multicolor fluorescence effect enabling promising applications in visualized displays and sensing. Finally, the fabricated TENG features a short‐circuit current density of ~61.8 mA/m2 and a maximum peak power density of ~11.7 W/m2, exceeding that of most state‐of‐the‐art nanofiber‐based TENG reported to date. As a demonstration of application potential, this TENG shows the energy‐harvesting ability to charge capacitors and light up 125 green LEDs and self‐powered sensing capability for human motion monitoring. This work provides insights for exploiting novel tribomaterials for high‐output TENGs with promising potential in biomechanical energy harvesting, self‐powered sensing, and so forth.

ABSTRACTRegulated cell death (RCD) is considered a vital process in cancer therapy, determining treatment outcomes and facilitating the eradication of cancer cells. As an emerging type of RCD, PANoptosis features excellent antineoplastic effects due to its combination of death modes, including pyroptosis, apoptosis, and necroptosis. In this work, anion‐cation vacancies (oxygen/titanium‐vacancy‐rich) ultrathin HTiO nanosheets with outstanding sonocatalytic performance and peroxidase‐mimicking activity are rationally engineered for the disruption of mitochondrial function in tumor cells and the destabilization of redox homeostasis, ultimately inducing tumor PANoptosis. The utilization of external ultrasound energy amplifies the production of toxic reactive oxygen species (ROS). Density functional theory calculations indicate that the oxygen and titanium vacancies generated in HTiO nanosheets enhance the ROS generation efficiency by promoting carrier separation and increasing the adsorption capacity of H2O2. The advantages of triggering PANoptosis are substantially evidenced by exceptional antineoplastic efficacy both at the cellular level and on two in vivo separate tumor xenografts (4T1 and MDA‐MB‐231 breast tumors). This work highlights a distinct type of titanium‐based nanostructure with a multimodal synergistic integration of sonocatalytic and enzymatic therapies, offering an alternative but highly efficient strategy for fabricating vacancy‐engineered sonocatalytic biomaterials with optimized therapeutic performance in tumor treatment.

ABSTRACTTwo‐dimensional (2D) transition metal carbides, carbonitrides, and nitrides, known as MXenes, have been widely studied at the frontier of 2D materials. The excellent mechanical properties, electrical conductivity, excellent photoelectrical performance, and good thermal stability of MXenes enable wide applications in many fields, including but not limited to energy storage, supercapacitors, EMI shielding, catalysis, optoelectronics, and sensors. In particular, MXene‐based materials exhibit exceptional sensing performance due to their unique tunable surface chemistry, 2D architecture, and exotic electrical/mechanical/electromechanical properties, which are rarely found in other materials. This paper discusses the MXene sensing properties and their mechanisms in different types of sensors, including piezoresistive sensors, flexible sensors, gas sensors, and biosensors. The unique roles of these MXene‐based sensors toward the future of smart living are also outlined. This article may shed light on the rational design of MXene‐based sensors and provide valuable references for corresponding scenario applications.

ABSTRACTHigh‐strength fibers have attracted intensive attention owing to their promising applications in various fields. However, the continuous fabrication of polyelectrolyte fibers with ultra‐strong mechanical properties remains a great challenge. Herein, we present a scalable microgroove‐based continuous‐spinning strategy of polyelectrolyte nanocomposite fibers. The shear flow induced the unraveling and aligning of the irregularly coiled polymer chains, which allowed the polyelectrolyte chains to fully contact each other after coalescing and enhanced the interaction between them. Nanocomposite fibers were prepared by adding two‐dimensional nanofillers into the negatively charged reaction solution. The nanocomposite fibers with aligned polymers and nanosheets exhibit excellent mechanical properties, with a tensile strength of up to 1783.8 ± 47.1 MPa and a modulus as high as 183.5 ± 4.6 GPa. Quantitative analysis indicates that the shear flow induced orientation of polymer chains and the well aligned nanosheets, as well as the strong interactions of polymer matrix form a dense and ordered structure, all these results in the observed mechanical properties. Moreover, we believe that our strategy could be extended to a variety of other polyelectrolytes and lead to the development of high‐performance fibers.

ABSTRACTFor a clean and sustainable society, there is an urgent demand for renewable energy with net‐zero emissions due to fossil fuels limited resources and irreversible environmental impact. Hydrogen has the unrivaled potential to replace fossil fuels due to its high gravimetric energy density, abundant sources (H2O), and environmental friendliness. However, its low volumetric energy density causes significant challenges, inspiring major efforts to develop chemical‐based storage alternatives. Solid‐state hydrogen storage in materials has substantial potential for fulfilling the practical requirements and is recognized as a potential candidate due to their properties tuning more independently. However, hydrogen's stable thermodynamics and sluggish kinetics are the bottleneck to its widespread applications. To explore the kinetic and thermodynamic barriers in the fundamentals of hydrogen storage materials, this review will provide promising information for researchers to gain detailed knowledge about hydrogen storage energy applications and find new routes for materials engineering with tuned properties. This will further attract a wider scientific community and intend to understand the innovative concepts and strategies developed and to employ them in tailoring hydrogen storage materials' kinetic and thermodynamic properties. Recent advances in nanostructuring, nanoconfinement with in situ catalysts, and host/guest stress/strain engineering have the potential to propel the prospects of tailoring the hydrogen storage materials properties at the nanoscale with several promising directions and strategies that could lead to the next generation of solid‐state hydrogen storage practical applications.

ABSTRACTHumanoid robots have garnered substantial attention recently in both academia and industry. These robots are becoming increasingly sophisticated and intelligent, as seen in health care, education, customer service, logistics, security, space exploration, and so forth. Central to these technological advancements is tactile perception, a crucial modality through which humanoid robots exchange information with their external environment, thereby facilitating human‐like behaviors such as object recognition and dexterous manipulation. Texture perception is particularly vital for these tasks, as the surface morphology of objects significantly influences recognition and manipulation abilities. This review addresses the recent progress in tactile sensing and machine learning for texture perception in humanoid robots. We first examine the design and working principles of tactile sensors employed in texture perception, differentiating between touch‐based and sliding‐based approaches. Subsequently, we delve into the machine learning algorithms implemented for texture perception using these tactile sensors. Finally, we discuss the challenges and future opportunities in this evolving field. This review aims to provide insights into the state‐of‐the‐art developments and foster advancements in tactile sensing and machine learning for texture perception in humanoid robotics.

AbstractAnode‐free lithium metal batteries (AFLMBs), also known as lithium metal batteries (LMBs) with zero excess lithium, have garnered significant attention due to their substantially higher energy density compared to conventional lithium metal anodes, improved safety characteristics, and lower production costs. However, the current cycling stability of AFLMBs faces formidable challenges primarily caused by significant lithium loss associated with the deposition of lithium metal. Therefore, this review focuses on the crucial aspects of lithium metal nucleation and growth on the anode side. Respectively, aiming to provide an in‐depth understanding of the deposition mechanisms, comprehensively summarize the corresponding scientific influencing factors, and analyze specific strategies for addressing these issues through the integration of relevant exemplary cases. Importantly, this review endeavors to offer a profound explication of the scientific essence and intricate mechanisms that underlie the diverse modification strategies. This review possesses the inherent capacity to greatly facilitate the progress and enlightenment of research in this field, offering a valuable resource for the researchers.

ABSTRACTEfficient and cost‐effective catalysts for oxygen reduction reaction (ORR) are crucial for the commercialization of metal‐air batteries. In this study, we utilized theoretical calculations to guide the material synthesis strategy for preparing catalysts. Using density functional theory (DFT) calculations, we systematically explored the ORR performance of metal metaphosphates (A‐M(PO3)2, B‐M(PO3)2, M = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn) with both amorphous and crystalline structures. Amorphous A‐Mn(PO3)2 showed optimal adsorption energy and the lowest ORR overpotential of 0.32 eV. Phytic acid was employed as a phosphorus source, and the chelating structure of phytic acid molecules and metal ions was broken through the “metal ion pre‐adsorption and spatial confinement strategy” of carbon materials with electron‐rich centers. Following high‐temperature calcination, we successfully prepared a series of amorphous metal metaphosphate composite catalysts for the first time. In 0.1 M KOH electrolyte, both amorphous Mn(PO3)2‐C/C3N4/CQDs (carbon quantum dots) and Mn(PO3)2‐C/C3N4/CNTs (carbon nanotubes) exhibited excellent ORR catalytic activity, with half‐wave potentials of 0.85 V and 0.80 V, respectively. A linear correlation between theoretical overpotentials and experimental half‐wave potentials was discovered through comparison. This work could open a new avenue to the discovery of highly efficient non‐precious metal‐based catalysts with amorphous structures.

ABSTRACTBioinspired energy‐autonomous interactive electronics are prevalent. However, self‐powered artificial skins are often challenging to be combined with excellent mechanical properties, optical transparency, autonomous attachability, and biocompatibility. Herein, a robust ecological polyionic skin (polyionic eco‐skin) based on triboelectric mechanism consisting of ethyl cellulose/waterborne polyurethane/Cu nanoparticles (EWC) green electroactive sensitive material and polyethylene oxide/waterborne polyurethane/phytic acid (PWP) polyionic current collector is proposed. The polyionic eco‐skin features sufficient stretchability (90%) and low Young's modulus (0.8 MPa) close to that of human soft tissue, high transparency (> 84% of transmission) in the visible light range, and broad static/dynamic adhesiveness, which endows it with strong adaptive implementation capacity in flexible curved electronics. More importantly, the self‐powered polyionic eco‐skin exhibits enhanced force‐electric conversion performance by coordinating the effect of nanoparticle‐polymer interfacial polarization and porous structure of sensitive material. Integrating multiple characteristics enables the polyionic eco‐skin to effectively convert biomechanical energy into electrical energy, supporting self‐powered functionality for itself and related circuits. Moreover, the eco‐skin can be utilized to construct an interactive system and realize the remote noncontact manipulation of targets. The polyionic eco‐skin holds tremendous application potential in self‐powered security systems, human–machine interaction interfaces, and bionic robots, which is expected to inject new vitality into a human–cyber–physical intelligence integration.

ABSTRACTDirect hydrazine‐hydrogen peroxide fuel cells (DHzHPFCs) offer unique advantages for air‐independent applications, but their commercialization is impeded by the lack of high‐performance and low‐cost catalysts. This study reports a novel dual‐site Co‐Zn catalyst designed to enhance the hydrazine oxidation reaction (HzOR) activity. Density functional theory calculations suggested that incorporating Zn into Co catalysts can weaken the binding strength of the crucial N2H3* intermediate, which limits the rate‐determining N2H3* desorption step. The synthesized p‐Co9Zn1 catalyst exhibited a remarkably low reaction potential of −0.15 V versus RHE at 10 mA cm−2, outperforming monometallic Co catalysts. Experimental and computational analyses revealed dual active sites at the Co/ZnO interface, which facilitate N2H3* desorption and subsequent N2H2* formation. A liquid N2H4‐H2O2 fuel cell with p‐Co9Zn1 catalyst achieved a high open circuit voltage of 1.916 V and a maximum power density of 195 mW cm−2, demonstrating the potential application of the dual‐site Co‐Zn catalyst. This rational design strategy of tuning the N2H3* binding energy through bimetallic interactions provides a pathway for developing efficient and economical non‐precious metal electrocatalysts for DHzHPFCs.