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[Display omitted] Self-supporting tree skeleton and densely stackable phenolic resin are cleverly coupled together by a "rebar-concrete" structure. The thick electrode as a master of space utilization has extremely high areal and volumetric energy density. This work confirms the effective coupling of the self-supporting skeleton and powder materials, providing novel ideas for the preparation of thick electrodes with high mass loading. • A "rebar-concrete" structure is proposed to facilitate the high space utilization of thick electrodes. • The areal capacitance of the thick electrode reaches an astonishing 11F cm−2. • The assembled SSC device delivers competitive areal energy density of 0.63 mWh cm−2. The thick electrode design with high packing density of active materials can increase the capacity in a limited space. However, the key challenge is still to develop a system with high space utilization and ensure electron/ion transport in thick electrode. This work proposes an interesting "rebar-concrete" structure, which successfully prepared wood/phenolic resin-derived thick electrode with high space utilization by in-situ polymerization of phenolic resin (concrete) in the wood (rebar) channel. The electrode exhibits an excellent three-dimensional interconnected hierarchical pore structure due to the uniform activation of in-situ anchored KOH particles. The mass loading (35 mg cm−2) and areal capacitance (11F cm−2) of the obtained composite electrode are increased to 446 % and 1257 % of the original balsa wood, respectively. The assembled symmetric supercapacitor (SSC) exhibits a high energy density of 0.63 mWh cm−2 (3.91 mWh cm−3) and an excellent cycle stability (95 % retention after 50 000 cycles), showing good practicability in lighting LEDs or driving a fan. This strategy achieves effective coupling of self-supporting skeleton and powder materials, providing more insights and possibilities for the preparation of high energy density thick electrodes. [ABSTRACT FROM AUTHOR]

[Display omitted] • This review focuses on recent development of carbon dots/porous materials composites. • Preparation, structures, and properties of carbon dots/porous materials composites are discussed. • Challenges and future development of carbon dots/porous materials composites are described. Carbon dots (CDs), an emerging fluorescent carbon nanomaterial, have attracted great attention in recent year due to their features such as unique optical property, good biocompatibility and low cost and easy synthesis. When CDs are integrated with porous materials, it not only compensates for the shortcomings of monocomponent CDs in applications, but also produces new functionalities through synergistic interactions to extend new applications. At present, CDs have been assembled with various porous materials such as zeolites, carbonaceous porous materials, porous graphitic carbon nitride (g-C 3 N 4), mesoporous SiO 2 , porous metallic compounds and metal-organic frameworks (MOFs), which exhibit excellent performance and a wide range of applications. Therefore, recent research advances in CDs/porous materials composites should be presented to facilitate further development of the field. In this article, the preparation methods, porous structures, and properties of CDs/porous materials composites are classified and presented. Then, the applications of CDs/porous materials composites in optics, biomedicine, sensing, electrochemistry, and photocatalysis are also discussed. Finally, current challenges and future directions are briefly discussed to facilitate the next development of CDs/porous materials composites. [ABSTRACT FROM AUTHOR]

[Display omitted] • This review focuses on recent development of carbon dots/porous materials composites. • Preparation, structures, and properties of carbon dots/porous materials composites are discussed. • Challenges and future development of carbon dots/porous materials composites are described. Carbon dots (CDs), an emerging fluorescent carbon nanomaterial, have attracted great attention in recent year due to their features such as unique optical property, good biocompatibility and low cost and easy synthesis. When CDs are integrated with porous materials, it not only compensates for the shortcomings of monocomponent CDs in applications, but also produces new functionalities through synergistic interactions to extend new applications. At present, CDs have been assembled with various porous materials such as zeolites, carbonaceous porous materials, porous graphitic carbon nitride (g-C 3 N 4), mesoporous SiO 2 , porous metallic compounds and metal-organic frameworks (MOFs), which exhibit excellent performance and a wide range of applications. Therefore, recent research advances in CDs/porous materials composites should be presented to facilitate further development of the field. In this article, the preparation methods, porous structures, and properties of CDs/porous materials composites are classified and presented. Then, the applications of CDs/porous materials composites in optics, biomedicine, sensing, electrochemistry, and photocatalysis are also discussed. Finally, current challenges and future directions are briefly discussed to facilitate the next development of CDs/porous materials composites. [ABSTRACT FROM AUTHOR]

• A green and common method was proposed to prepare biomimetic actuators. • The PNPB actuator showed excellent multi-stimulus response and synergistic effect. • Anisotropic natural bamboo endowed the PNPB actuator programmable performance. • The PNPB actuator had application potential in complex environment. Hydrogel actuators with controllable deformation and excellent biocompatibility are widely used in soft robot, valve, drug delivery and lenses. However, the stimulation response performance of existing hydrogel actuators mostly focuses on a single active layer, which greatly affects its driving performance and service life. In this work, we integrate temperature-responsive hydrogel (Poly (N-isopropyl acrylamide), PNIPAM) and pH-responsive hydrogel (polyacrylic acid, PAAc) into one system to fabricate a dual active layer composite hydrogel actuator with high performance. Based on the PAAc hydrogels achieving contract or expand at different pH values, the obtained actuator exhibits admirable bidirectional bending characteristics. In addition, the anisotropic bamboo sheet endows the hydrogel actuator with programmable 3 D complex deformation. Benefitting from the synergy and different responsiveness between the two active layers, the hydrogel actuator not only has multiple response performance, but also greatly improves its deformation degree and response speed. More importantly, these promising properties of the actuator have broad application prospects in the development of pattern design and intelligent switch. This work proposes a promising strategy for the structural design of hydrogel actuators with excellent performance, and encourages more exploration of the application range of the actuator. [ABSTRACT FROM AUTHOR]

• The morph-genetic method was innovatively used to fabricate the ABH actuator. • The ABH actuator exhibits promising comprehensive performance. • The assembled biomimetic actuators show excellent synergistic performance. • The biomimetic actuator shows potential for a variety of applications. Stimuli-responsive hydrogels are most promising for the fabrication of autonomous bio-mimetic soft actuators. However, their weak actuation forces and isotropic volume change hinder their practical utilization as versatile actuators, owing to their fragility. Herein, we used the morph-genetic method to fabricate anisotropic bamboo/poly(N-isopropylacrylamide) hydrogel (ABH) complex for use as soft actuator. First of all, the bamboo fiber structure provides an anisotropic framework for the ABH actuator to achieve precise deformational programmability. Secondly, benefiting from the ultra-high directional strength (110 MPa) of bamboo, ABH actuator exhibits sufficiently robust mechanical property, which generates a powerful actuating force. Lastly, owing to the regulation of bamboo sheet and PNIPAM hydrogel, the ABH actuator not only achieves ultra-fast response speed (825°/s of the bending speed), but also has excellent synergetic performance. We demonstrate several bio-mimetic actuating devices based on ABH actuator, inspired by the intricate motions of natural organisms, to highlight how the specific materials properties and their synergy can be systematically exploited for the rational design of soft actuators. Henceforth, it is anticipated that the development of hydrogel actuators could continue to benefit from the use of various naturally-anisotropic materials, such as shape-memory polymers or liquid crystals, for the preparation of further advanced hydrogel actuators by the morph-genetic method. [ABSTRACT FROM AUTHOR]

• PPy-coated P(NIPAM-ABP) electrospun nanofiber can provide high strength. • PPy-coating by in situ polymerization can provide high light-responsive. • The actuator owns ultrafast deformation and rapid recovery. • The actuator can realize various 3D programmable complex deformations. • We have explored new biomimetic devices based on the advantages of the actuator. Intelligent hydrogels are promising for biomimetic actuators, but acquiring actuations with both high speed and powerful force is still extremely difficult. Herein, a new robust polypyrrole (PPy)-coated copoly(isopropylacrylamide-4-benzoylphenyl acrylate) [P(NIPAM-ABP)] electrospun light-responsive hydrogel is explored. The (PPy)-coated P(NIPAM-ABP) hydrogel can be obtained via in-situ polymerization of pyrroles on the nanofiber-oriented electrospun P(NIPAM-ABP) hydrogel. Compared with original P(NIPAM-ABP) hydrogel, this PPy-coated P(NIPAM-ABP) hydrogel can integrate highly-enhanced mechanical strength (from 1.21 to 5.12 MPa of tensile strength) and ultrahigh-efficiency of photothermal conversion together. In addition, the orientation of P(NIPAM-ABP) nanofibers can still maintain well for programmable complex deformations. Consequently, the as-prepared robust bi-hydrogel actuator with ultrafast and complex deformations has been achieved, through bonding the PPy-P(NIPAM-ABP) hydrogel membrane with a polyethylene glycol diacrylate-cellulose nanofiber (PEGDA-CNF) composite hydrogel membrane via interfacial ultraviolet (UV) polymerization of PEGDA monomers. Several light-responsive biomimetic actuating devices have been achieved, which owning powerful force (can grab up 100 times of self-weight), rapid speed (1285.71°/s of folding) or precisely programmable complex deformations. Furthermore, two biomimetic devices with synergistic functions of the three advantages above have been explored, which can mimic the child's sit-up and the starfish's continuous crawling movement respectively. This work provides a robust remotely-controlled light-responsive hydrogel actuator with powerful force, ultrafast speed and programmable complex actuations, which will inspire the design and fabrication of novel soft biomimetic actuating materials and systems. [ABSTRACT FROM AUTHOR]

Near-infrared light-responsive hydrogel actuator with complex deformations and remote precise control is fabricated from the natural bamboo. The resulting biomimetic bamboo/PNIPAM hydrogel actuator can be precisely designed to perform a variety of simulations. [Display omitted] • Biomimetic actuators based on anisotropic natural bamboo were prepared. • Nigrosine was first used to fabricate light-responsive hydrogel actuator. • The actuator exhibits outstanding programmability and remote-control performance. • The actuator can move freely on the water surface based on Marangoni effect. Near-infrared light-responsive hydrogels are one of the most important soft biomimetic actuators owing to their accuracy, remote control performance, and permeability. However, the complex deformations and materials of hydrogel actuators are still a serious challenge. Herein, we have developed a novel composite hydrogel actuator by combining natural bamboo sheet and nigrosine/poly(N-isopropylacrylamide) (PNIPAM) composite hydrogel. The high-efficient photothermal conversion of the nigrosine/PNIPAM composite hydrogel sheet generates light-responsive actuation that is remotely controllable. Furthermore, the bamboo sheet with fiber-oriented structure can be cut at different angles, which facilitates programmable 3D complex deformations in the actuator. Accordingly, we have designed a series of biomimetic actuating devices, including simulations of butterfly antenna, Dendrobium , smart switch, and even a multi-step deformational biomimetic claw. In addition, we also explored a biomimetic insect with precisely-controlled fast movements on the water surface based on Marangoni effect. This work provides a simple but general strategy for fabricating biomimetic actuators and will inspire new designs for intelligent soft actuators. [ABSTRACT FROM AUTHOR]

A reusable magnetic WC-Co composite (Co/C-1000) filter with efficient water treatment was prepared by in-situ growth of ZIF-67 on the inside and outside surface of wood following by carbonization. [Display omitted] • Magnetic WC-Co composite is designed for wastewater treatment. • WC-Co composite has ultra-high dyes adsorption capacity. • The Co/C-1000 filter has good removal efficiency for high dye concentration solution at a higher flux. • The Co/C-1000 filter with excellent thermal stability can be recycled by simple burning method. Organic dye in water is a crucial global environmental problem. Notably, dyes, especially anionic dye Congo red (CR) and cationic dye Methylene blue (MB), have carcinogenic and mutagenic effects on human health. However, the commercial activated carbon with bad reusability is difficult to collect, which results in poor actual adsorption. In this paper, ZIF-67@wood obtained by in situ growth of ZIF-67 on wood is carbonized to prepare magnetic WC-Co composites. The hierarchical porous structure of wood can facilitate the rapid passage of dye solution, and promote full contact between magnetic core–shell Co/C nanoparticles and dyes. The adsorption capacities of CR and MB by Co/C-1000 are 1117.03 and 805.08 mg g−1, respectively. The pH pzc (7.9) of Co/C-1000 is then determined. When the dye concentration reaches 1200 mg L−1, the removal efficiency of Co/C-1000 reaches 99.98% under gravity. With the flux of 1.0 × 104 L m−2h−1 for CR solution (100 mg L−1), the removal efficiency of Co/C-1000 filter connected with peristaltic pump is almost 99.28%. In addition, the Co/C-1000 filter with high reusability and the adsorbed dyes can be removed by simple burning. This economical, recyclable and self-supporting filter with ultra-high adsorption capacity feature has the potential to replace commercial activated carbon and it will be widely used in practical wastewater treatment. [ABSTRACT FROM AUTHOR]

A reusable magnetic WC-Co composite (Co/C-1000) filter with efficient water treatment was prepared by in-situ growth of ZIF-67 on the inside and outside surface of wood following by carbonization. [Display omitted] • Magnetic WC-Co composite is designed for wastewater treatment. • WC-Co composite has ultra-high dyes adsorption capacity. • The Co/C-1000 filter has good removal efficiency for high dye concentration solution at a higher flux. • The Co/C-1000 filter with excellent thermal stability can be recycled by simple burning method. Organic dye in water is a crucial global environmental problem. Notably, dyes, especially anionic dye Congo red (CR) and cationic dye Methylene blue (MB), have carcinogenic and mutagenic effects on human health. However, the commercial activated carbon with bad reusability is difficult to collect, which results in poor actual adsorption. In this paper, ZIF-67@wood obtained by in situ growth of ZIF-67 on wood is carbonized to prepare magnetic WC-Co composites. The hierarchical porous structure of wood can facilitate the rapid passage of dye solution, and promote full contact between magnetic core–shell Co/C nanoparticles and dyes. The adsorption capacities of CR and MB by Co/C-1000 are 1117.03 and 805.08 mg g−1, respectively. The pH pzc (7.9) of Co/C-1000 is then determined. When the dye concentration reaches 1200 mg L−1, the removal efficiency of Co/C-1000 reaches 99.98% under gravity. With the flux of 1.0 × 104 L m−2h−1 for CR solution (100 mg L−1), the removal efficiency of Co/C-1000 filter connected with peristaltic pump is almost 99.28%. In addition, the Co/C-1000 filter with high reusability and the adsorbed dyes can be removed by simple burning. This economical, recyclable and self-supporting filter with ultra-high adsorption capacity feature has the potential to replace commercial activated carbon and it will be widely used in practical wastewater treatment. [ABSTRACT FROM AUTHOR]

[Display omitted] • The actuator can achieve synergistic movement of deformation and transportation. • Added Fe 3 O 4 NPs provide both magnetism and high-efficient photothermal conversion. • The hydrogel actuator owns high tensile-strength of 4.59 MPa via electrospinning. • The actuator can provide ultrafast deformational speed of 178°/s. • We have explored new bio-inspired systems with two/multi-step synergic actuation. As a soft/wet intelligent material, hydrogel actuators with multiple stimuli-responsiveness have been widely developed. However, it is still greatly difficult for them to integrate bi/multiple responsiveness together for bio-mimetic synergistic actuation. Here, we have explored a high-strength anisotropic bi-layer hydrogel actuator with P(NIPAM-ABP) layer and Fe 3 O 4 /PAN layer via electrospinning technique, which can provide programmable bi-functional synergistic movement. The Fe 3 O 4 /PAN layer can provide magnetic responsive navigation for long-range transportation on account of the magnetism of the Fe 3 O 4 nanoparticles. Furthermore, the ultrahigh photothermal conversion efficiency of the Fe 3 O 4 nanoparticles in the Fe 3 O 4 /PAN layer, can endow the P(NIPAM-ABP) layer with fast remotely-controlled photothermal-responsive deformation. Most importantly, this hydrogel actuator can achieve complex higher-level programmable movements than before based on the synergy of remotely-controlled deformation and the long-range transportation, which can be utilized to design various novel bio-mimetic soft-robots. Last but not least, the introduction of the electrospinning, not only can achieve high strength (4.59 MPa of tensile strength) of this bi-layer hydrogel, but also can provide both ultrafast (178°/s) and programmable complex photothermal-responsiveness, owing to the ultrahigh specific surface area (ultra-thin and porous structure) and excellent orientation of the thermal-responsive P(NIPAM-ABP) nanofibers respectively. This work will provide a general method via electrospinning for anisotropic hydrogel actuator with bi/multiple-functional synergy and will provide a new strategy for smart actuators and other bio-mimetic intelligent materials/systems. [ABSTRACT FROM AUTHOR]

• A new double-network hydrogel is explored for uranium recovery from seawater. • U-adsorption capacity of the hydrogel is greatly enhanced by added nanoclay. • Mechanical property of the hydrogel is largely improved by th double-network. • Used materials are lowcost and the hydrogel owns good U-adsorption reusability. Massive uranium recovery from seawater is a key project to provide the long-time consumption of global nuclear power, while it is still greatly difficult to achieve high-efficient adsorbents with high mechanical property. In this work, a new nanoclay-poly(amidoxime) (NC-PAO) high-strength double-network (DN) composite hydrogel adsorbent with high-efficient and fast uranium extraction capacity has been explored. The uranium adsorbing performance can be significantly enhanced by the small content of added super-hydrophilic NC (Laponite RDS sheets), because of the largely improved hydrophilicity of the hydrogel. Compared with the blank PAO DN hydrogel without nanoclay, the uranium adsorbing capacity of this NC-PAO DN hydrogel can largely increase 73.4% from 4.97 mg/g to 8.62 mg/g, after in seawater only 25 days. The uranium adsorption rate of this hydrogel from natural seawater, can reached 0.345 mg/(g∙day), which is excellent among existing uranium adsorbents. Furthermore, this hydrogel has high mechanical performance with 2.42 MPa of tensile strength and 16.13 MPa of compressive strength, which can be used in seawater for relatively longer time than traditional low-strength single-network hydrogel, owing to its double network (DN) structure (the weakly crosslinked gelatin soft network and the strongly crosslinked cellulose nanofiber (CNF) hard network). This NC-PAO DN hydrogel adsorbent will be an excellent candidate for fast uranium recovery from seawater in largescale. Most importantly, this work will inspire the development of new hydrogel-based adsorbents and even other type of adsorbents for high-efficient uranium extraction, through compositing various low-cost and super-hydrophilic nanomaterials to significantly improve the hydrophilicity of the adsorbent and designing double-network structure to largely enhance the mechanical property. [ABSTRACT FROM AUTHOR]

[Display omitted] • High P-doped (9.24 at%) thick carbon electrodes (CW-P) by phytic acid treatment. • SSC exhibits high capacitance of 4.7F cm−2/206.5F g−1 at 1.0 mA cm−2. • Excellent capacitance retention of 90.5% after 20 000 cycles (@20 mA cm−2). • High energy density up to 0.94 mW h cm−2 (41.2 Wh kg−1). • High power density up to 0.6 mW cm−2 (26.3 W kg−1). Keeping outstanding electrochemical performance under high mass loading is critical to develop functional thick electrodes. Here, we report a high phosphorus-doped wood-derived carbon thick electrode for supercapacitor via phytic acid treatment, which can form hydrogen bonds with cellulose molecules in the wood. The content of phosphorus reaches up to 9.24 at% in carbonized wood with P-doping (CW-P-9.24), higher than most previously reported P-doped carbonaceous materials. CW-P-9.24 electrode (800 μm, 17.17 mg cm−2) exhibits greatly improved electrochemical performance, especially in energy density and cyclic stability. Significantly, the symmetrical supercapacitor device exhibits high areal and specific capacitance of 4.7 F cm−2 and 206.5 F g−1 at 1.0 mA cm−2 with prominent retention of 90.5% through the long-term cycling at 20 mA cm−2 for 20,000 cycles, and 0.94 mW h cm−2 (41.2 Wh kg−1) at power density of 0.6 mW cm−2 (26.3 W kg−1), and possesses excellent volumetric capacitance and energy density of 29.3 F cm−3 and 5.8 Wh cm−3, respectively. The outstanding performance can be attributed to the excellent hierarchical structure, low tortuosity, and high phosphorus doping with fast accessible channels at high current density. The extraordinary performance of CW-P has been elucidated by density functional theory calculations, which confirm the enhanced activity by P-doping. These results demonstrate that the CW-P electrode is promising for practical application in energy storage devices and encourage more investigations for thick electrode. [ABSTRACT FROM AUTHOR]