Abstract
Transition metal oxides (TMOs) are promising electrochromic (EC) materials for applications such as smart windows and displays, yet the challenge still exists to achieve good flexibility, ...high coloration efficiency and fast response simultaneously. MXenes (e.g. Ti
3
C
2
T
x
) and their derived TMOs (e.g. 2D TiO
2
) are good candidates for high-performance and flexible EC devices because of their 2D nature and the possibility of assembling them into loosely networked structures. Here we demonstrate flexible, fast, and high-coloration-efficiency EC devices based on self-assembled 2D TiO
2
/Ti
3
C
2
T
x
heterostructures, with the Ti
3
C
2
T
x
layer as the transparent electrode, and the 2D TiO
2
layer as the EC layer. Benefiting from the well-balanced porosity and connectivity of these assembled nanometer-thick heterostructures, they present fast and efficient ion and electron transport, as well as superior mechanical and electrochemical stability. We further demonstrate large-area flexible devices which could potentially be integrated onto curved and flexible surfaces for future ubiquitous electronics.
Biomechanical energy harvesting textiles based on nanogenerators that convert mechanical energy into electricity have broad application prospects in next-generation wearable electronic devices. ...However, the difficult-to-weave structure, limited flexibility and stretchability, small device size and poor weatherability of conventional nanogenerator-based devices have largely hindered their real-world application. Here, we report a highly stretchable triboelectric yarn that involves unique structure design based on intrinsically elastic silicone rubber tubes and extrinsically elastic built-in stainless steel yarns. By using a modified melt-spinning method, we realize scalable-manufacture of the self-powered yarn. A hundred-meter-length triboelectric yarn is demonstrated, but not limited to this size. The triboelectric yarn shows a large working strain (200%) and promising output. Moreover, it has superior performance in liquid, therefore showing all-weather durability. We also show that the development of this energy yarn facilitates the manufacturing of large-area self-powered textiles and provide an attractive direction for the study of amphibious wearable technologies.
The fabrication of a flexible thermoelectric (TE) device that contains flexible, all‐inorganic hybrid thin films (p‐type single‐wall carbon nanotubes (SWCNTs)/Sb2Te3 and n‐type reduced graphene oxide ...(RGO)/Bi2Te3) is reported. The optimized power factors of the p‐type and n‐type hybrid thin films at ambient temperature are about 55 and 108 µW m−1 K−2, respectively. The high performance of these films that are fabricated through the combination of vacuum filtration and annealing can be attributed to their planar orientation and network structure. In addition, a TE device, with 10 couples of legs, shows an output power of 23.6 µW at a temperature gradient of 70 K. A prototype of an integrated photovoltaic‐TE (PV‐TE) device demonstrates the ability to harvest low‐grade “waste” thermal energy from the human body and solar irradiation. The flexible TE and PV‐TE device have great potential in wearable energy harvesting and management.
A flexible thermoelectric generator based on all‐inorganic hybrid films of n‐type RGO/Bi2Te3 and p‐type SWCNTs/Sb2Te3 is fabricated. The prototypes of a wearable wrist band and a photovoltaic–thermoelectric integrated device are proven, which can be used for harvesting waste heat and stabilizing the photovoltaic performance.
Developing fabric-based electronics with good wearability is undoubtedly an urgent demand for wearable technologies. Although the state-of-the-art fabric-based wearable devices have shown unique ...advantages in the field of e-textiles, further efforts should be made before achieving "electronic clothing" due to the hard challenge of optimally unifying both promising electrical performance and comfortability in single device. Here, we report an all-fiber tribo-ferroelectric synergistic e-textile with outstanding thermal-moisture comfortability. Owing to a tribo-ferroelectric synergistic effect introduced by ferroelectric polymer nanofibers, the maximum peak power density of the e-textile reaches 5.2 W m
under low frequency motion, which is 7 times that of the state-of-the-art breathable triboelectric textiles. Electronic nanofiber materials form hierarchical networks in the e-textile hence lead to moisture wicking, which contributes to outstanding thermal-moisture comfortability of the e-textile. The all-fiber electronics is reliable in complicated real-life situation. Therefore, it is an idea prototypical example for electronic clothing.
3D cellular graphene films with open porosity, high electrical conductivity, and good tensile strength, can be synthesized by a method combining freeze‐casting and filtration. The resulting ...supercapacitors based on 3D porous reduced graphene oxide (RGO) film exhibit extremely high specific power densities and high energy densities. The fabrication process provides an effective means for controlling the pore size, electronic conductivity, and loading mass of the electrode materials, toward devices with high energy‐storage performance.
Freestanding, flexible/foldable, and wearable bifuctional ultrathin graphene paper for heating and cooling is fabricated as an active material in personal thermal management (PTM). The promising ...electrical conductivity grants the superior Joule heating for extra warmth of 42 °C using a low supply voltage around 3.2 V. Besides, based on its high out‐of‐plane thermal conductivity, the graphene paper provides passive cooling via thermal transmission from the human body to the environment within 7 s. The cooling effect of graphene paper is superior compared with that of the normal cotton fiber, and this advantage will become more prominent with the increased thickness difference. The present bifunctional graphene paper possesses high durability against bending cycles over 500 times and wash time over 1500 min, suggesting its great potential in wearable PTM.
A wearable personal thermal management device based on graphene paper is demonstrated with multiple construction designs. For heating, the temperature can be raised from 18 to 38 °C with a typical supply voltage of 3.2 V within 8 s. For cooling, the response time is greatly shortened from 150 to 7 s compared with normal cotton fabric.
Flexible thermoelectric generators (TEGs) provide a sustainable solution for directly harvesting low-grade heat from various curved surfaces, presenting a promising potential for feeding energy to ...personal-electronics or internet-of-things systems. Nevertheless, the room-temperature millivolt output of the cutting-edge all-solid-state flexible material-based TEGs (AF-TEGs) is still unappeasable for flexible electronics in practical applications. Here, we report on an AF-TEG consisting of a 3-level structure based on thin-film carbon nanotube (CNT) assemblies that can generate a high voltage (1.05 V) and sufficient outpower (0.95 mW) at moderate ΔT (~44 and 39 K, respectively) for powering an electrochromic device. The advanced nature of the AF-TEG is that conformation is highly adaptive and programmable, showing the surface suitability which can capture waste heat in both in-plane and out-of-plane direction. Moreover, an AF-TEG power management scheme is proposed for powering a commercial LED and an electronic thermometer, which indicate promising potential for practical applications.
The AF-TEG based on a 3-level structure principle using industrial CNT films is designed to harvest low-grade waste heat for powering the microelectronics, meanwhile the power management scheme was proposed to regulate the thermoelectric voltage for practical application. Display omitted
•Introducing a 3-level structure principle for fabricating the high-performance AF-TEG.•Large-area modification strategy for numerous p- and n-type CNT thermoelectric legs.•A high thermoelectric voltage of 1.05 V can be generated by the AF-TEG at ΔT ≈ 44 K.•Power management scheme regulates the thermoelectric voltage for use in practice.
S, N co-doped graphene quantum dots (S,N-GQDs) coupled with P25 (TiO
2
) (S,N-GQD/P25) have been prepared via simply hydrothermal method. The as-prepared S,N-GQD/P25 composites exhibited excellent ...photocatalytic hydrogen generation activities, with a significantly extended light absorption range and superior durability without loading any noble metal cocatalyst. The photocatalytic activity of this composite under visible light (
λ
= 400–800 nm) was greatly improved compared with that of pure P25. This remarkable improvement in photocatalytic activity of the S,N-GQD/P25 composites can be attributed to that S,N-GQDs play a key role to enhance visible light absorption and facilitate the separation and transfer of photogenerated electrons and holes. Generally, this work could provide new insights into the facile fabrication of photocatalytic composites as high performance photocatalysts.
The ability to achieve simultaneous intrinsic deformation with fast response in commercially available materials that can safely contact skin continues to be an unresolved challenge for artificial ...actuating materials. Rather than using a microporous structure, here we show an ambient-driven actuator that takes advantage of inherent nanoscale molecular channels within a commercial perfluorosulfonic acid ionomer (PFSA) film, fabricated by simple solution processing to realize a rapid response, self-adaptive, and exceptionally stable actuation. Selective patterning of PFSA films on an inert soft substrate (polyethylene terephthalate film) facilitates the formation of a range of different geometries, including a 2D (two-dimensional) roll or 3D (three-dimensional) helical structure in response to vapor stimuli. Chemical modification of the surface allowed the development of a kirigami-inspired single-layer actuator for personal humidity and heat management through macroscale geometric design features, to afford a bilayer stimuli-responsive actuator with multicolor switching capability.
Origami-inspired active graphene-based paper with programmed gradients in vertical and lateral directions is developed to address many of the limitations of polymer active materials including slow ...response and violent operation methods. Specifically, we used function-designed graphene oxide as nanoscale building blocks to fabricate an all-graphene self-folding paper that has a single-component gradient structure. A functional device composed of this graphene paper can (i) adopt predesigned shapes, (ii) walk, and (iii) turn a corner. These processes can be remote-controlled by gentle light or heating. We believe that this self-folding material holds potential for a wide range of applications such as sensing, artificial muscles, and robotics.
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