Three-Dimensional Nanoporous Graphene-Carbon Nanotube Hybrid Frameworks for Confinement of SnS₂ Nanosheets: Flexible and Binder-Free Papers with Highly Reversible Lithium Storage

The practical applications of transition-metal dichalcogenides for lithium-ion batteries are severely inhibited by their inferior structural stability and electrical conductivity, which can be solved by optimizing these materials to nanostructures and confining them within conductive frameworks. Thus, we report a facile approach to prepare flexible papers with SnS₂ nanosheets (SnS₂ NSs) homogeneously dispersed and confined within the conductive graphene-carbon nanotube (CNT) hybrid frameworks. The confinement of SnS₂ NSs in graphene-CNT matrixes not only can effectively prevent their aggregation during the discharge–charge procedure, but also can assist facilitating ion transfer across the interfaces. As a result, the optimized SGC papers give an improved capacity of 1118.2 mA h g^–1 at 0.1 A g^–1 along with outstanding stability. This report demonstrates the significance of employing graphene-CNT matrixes for confinement of various active materials to fabricate flexible electrode materials

Nitrogen-Doped Carbon Nanofiber/Molybdenum Disulfide Nanocomposites Derived from Bacterial Cellulose for High-Efficiency Electrocatalytic Hydrogen Evolution Reaction

To remit energy crisis and environmental deterioration, non-noble metal nanocomposites have attracted extensive attention, acting as a fresh kind of cost-effective electrocatalysts for hydrogen evolution reaction (HER). In this work, hierarchically organized nitrogen-doped carbon nanofiber/molybdenum disulfide (pBC-N/MoS₂) nanocomposites were successfully prepared via the combination of in situ polymerization, high-temperature carbonization process, and hydrothermal reaction. Attributing to the uniform coating of polyaniline on the surface of bacterial cellulose, the nitrogen-doped carbon nanofiber network acts as an excellent three-dimensional template for hydrothermal growth of MoS₂ nanosheets. The obtained hierarchical pBC-N/MoS₂ nanocomposites exhibit excellent electrocatalytic activity for HER with small overpotential of 108 mV, high current density of 8.7 mA cm^–2 at η = 200 mV, low Tafel slope of 61 mV dec^–1, and even excellent stability. The greatly improved performance is benefiting from the highly exposed active edge sites of MoS₂ nanosheets, the intimate connection between MoS₂ nanosheets and the highly conductive nitrogen-doped carbon nanofibers and the three-dimensional networks thus formed. Therefore, this work provides a novel strategy for design and application of bacterial cellulose and MoS₂-based nanocomposites as cost-effective HER eletrocatalysts

Flexible Hybrid Membranes with Ni(OH)₂ Nanoplatelets Vertically Grown on Electrospun Carbon Nanofibers for High-Performance Supercapacitors

The practical applications of transition metal oxides and hydroxides for supercapacitors are restricted by their intrinsic poor conductivity, large volumetric expansion, and rapid capacitance fading upon cycling, which can be solved by optimizing these materials to nanostructures and confining them within conductive carbonaceous frameworks. In this work, flexible hybrid membranes with ultrathin Ni­(OH)₂ nanoplatelets vertically and uniformly anchored on the electrospun carbon nanofibers (CNF) have been facilely prepared as electrode materials for supercapacitors. The Ni­(OH)₂/CNF hybrid membranes with three-dimensional macroporous architectures as well as hierarchical nanostructures can provide open and continuous channels for rapid diffusion of electrolyte to access the electrochemically active Ni­(OH)₂ nanoplatelets. Moreover, the carbon nanofiber can act both as a conductive core to provide efficient transport of electrons for fast Faradaic redox reactions of the Ni­(OH)₂ sheath, and as a buffering matrix to mitigate the local volumetric expansion/contraction upon long-term cycling. As a consequence, the optimized Ni­(OH)₂/CNF hybrid membrane exhibits a high specific capacitance of 2523 F g^–1 (based on the mass of Ni­(OH)₂, that is 701 F g^–1 based on the total mass) at a scan rate of 5 mV s^–1. The Ni­(OH)₂/CNF hybrid membranes with high mechanical flexibility, superior electrical conductivity, and remarkably improved electrochemical capacitance are condsidered as promising flexible electrode materials for high-performance supercapacitors

Cotton Wool Derived Carbon Fiber Aerogel Supported Few-Layered MoSe₂ Nanosheets As Efficient Electrocatalysts for Hydrogen Evolution

Recent studies have proven that newly emerging two-dimensional molybdenum diselenide (MoSe₂) is a promising noble-metal-free electrocatalyst for hydrogen evolution reaction (HER). Increasing the exposures of the active edges of MoSe₂ nanostructures is a key issue to fully realize the excellent electrochemical properties of MoSe₂. In this work, a few-layered MoSe₂/carbon fiber aerogel (CFA) hybrids have been facilely obtained through the combination of high-temperature carbonization and one-pot solvothermal reaction. CFA derived from cotton wool is used as a three-dimensional conductive network for construction of hierarchical MoSe₂/CFA hybrids, where few-layered MoSe₂ nanosheets are uniformly and perpendicularly decorated on the surfaces of CFA. In the designed and prepared hybrids, CFA effectively increases the exposures of the active edges of MoSe₂ nanosheets as well as provides reduced lengths for both electron transportation and ion diffusion. Therefore, the obtained optimal MoSe₂/CFA hybrid exhibits excellent electrochemical activity as HER electrocatalyst with a small onset potential of −0.104 V vs reversible hydrogen electrode and a small Tafel slope of 62 mV per decade, showing its great potential as a next-generation Pt-free electrocatalyst for HER

Carbon-Nanotube-Incorporated Graphene Scroll-Sheet Conjoined Aerogels for Efficient Hydrogen Evolution Reaction

Developing low-cost Pt-free hydrogen evolution reaction (HER) electrocatalyst is highly desired in exploiting hydrogen as a sustainable new energy carrier. Herein, hierarchically structured graphene-carbon nanotube aerogel-MoSe₂ hybrid (GCA-MoSe₂) was constructed as efficient HER electrocatalysts. GCA was facilely fabricated by direct freeze-drying of graphene oxide (GO)-carbon nanotube (CNT) hybrid dispersion, with subsequent carbonization. Through a shock cooling method, a unique scroll-sheet conjoined architecture could be formed in GCA, which can function as highly conductive skeleton, thus facilitating the transport of electrons through the whole hybrids. Furthermore, CNTs acting as “spacers” between graphene layers can efficiently impede their restacking, thus giving full play to the superior electrical conductivity of graphene. The hierarchical porous aerogel skeleton could allow full impregnation of electrolyte, accelerating the ion diffusion kinetics. Benefiting from the three-dimensional (3D) network of GCA, MoSe₂ nanosheets can grow densely and perpendicularly on the aerogel, preventing them from aggregation to maximize the number of catalytic active sites on the edges. The ensemble of these benefits makes the hybrid an efficient electrocatalyst for HER, which exhibits an onset potential of 113 mV, small Tafel slope of 68 mV decade^–1 and good stability. Such a simple method of immobilizing guest nanosheets/particles in the host of GCA opens a new avenue for manufacturing macroscopic electrode materials in large scale

Laponite Nanodisks as an Efficient Platform for Doxorubicin Delivery to Cancer Cells

We report a facile approach to using laponite (LAP) nanodisks as a platform for efficient delivery of doxorubicin (DOX) to cancer cells. In this study, DOX was encapsulated into the interlayer space of LAP through an ionic exchange process with an exceptionally high loading efficiency of 98.3 ± 0.77%. The successful DOX loading was extensively characterized via different methods. <i>In vitro</i> drug release study shows that the release of DOX from LAP/DOX nanodisks is pH-dependent, and DOX is released at a quicker rate at acidic pH condition (pH = 5.4) than at physiological pH condition. Importantly, cell viability assay results reveal that LAP/DOX nanodisks display a much higher therapeutic efficacy in inhibiting the growth of a model cancer cell line (human epithelial carcinoma cells, KB cells) than free DOX drug at the same DOX concentration. The enhanced antitumor efficacy is primarily due to the much more cellular uptake of the LAP/DOX nanodisks than that of free DOX, which has been confirmed by confocal laser scanning microscope and flow cytometry analysis. The high DOX payload and enhanced antitumor efficacy render LAP nanodisks as a robust carrier system for different biomedical applications

Molybdenum Carbide Anchored on Graphene Nanoribbons as Highly Efficient All-pH Hydrogen Evolution Reaction Electrocatalyst

The demand for exploiting hydrogen as a new energy source has driven the development of feasible, efficient, and low-cost electrocatalysts for hydrogen evolution reaction (HER) in different reaction media. Herein, we report the synthesis of molybdenum carbide (Mo₂C) nanoparticles anchored on graphene nanoribbons (GNRs) as HER electrocatalyst that can function well under acidic, basic, and neutral conditions. GNRs obtained by unzipping carbon nanotubes (CNTs) display strip-like structure, offering abundant active sites for growing Mo₂C nanoparticles. Furthermore, GNRs could provide a fast electron transport pathway as well as large exposed surface area to allow full impregnation of electrolytes. Coupling with the anticorrosion feature of Mo₂C nanoparticles, the Mo₂C–GNR hybrid exhibits outstanding electrocatalytic performance in all of the acidic, basic, and neutral media, making it promising as a highly efficient electrocatalyst under conditions at all pH values

4D-Printed Bionic Soft Robot with Superior Mechanical Properties and Fast Near-Infrared Light Response

Inspired by natural organisms, a four-dimensional (4D)-printed starfish-like bionic soft robot (SBSR) was effectively prepared by integrating three-dimensional (3D) printing with smart hydrogels. The body of the SBSR is composed of a reduced graphene oxide-poly(N-isopropylacrylamide) hydrogel (rGO-PNH) with superior mechanical properties. In addition, the enhanced photothermal conversion effect was obtained by the reduction of graphene oxide nanosheets after the 3D printing process. Cylindrical actuators prepared using rGO-PNH exhibited bending and orientation toward the light source within 20 s of exposure to near-infrared light, thus demonstrating the rapid photoresponsivity of rGO-PNH. Furthermore, the 4D-printed SBSR showcased effective grasping, lifting, and releasing of objects by mimicking the predatory behavior of starfish. This study would provide insights into the development of responsive materials in 4D printable bionic soft robots and their applications in areas such as biomimetic devices and artificial muscles

4D-Printed Bionic Soft Robot with Superior Mechanical Properties and Fast Near-Infrared Light Response

Inspired by natural organisms, a four-dimensional (4D)-printed starfish-like bionic soft robot (SBSR) was effectively prepared by integrating three-dimensional (3D) printing with smart hydrogels. The body of the SBSR is composed of a reduced graphene oxide-poly(N-isopropylacrylamide) hydrogel (rGO-PNH) with superior mechanical properties. In addition, the enhanced photothermal conversion effect was obtained by the reduction of graphene oxide nanosheets after the 3D printing process. Cylindrical actuators prepared using rGO-PNH exhibited bending and orientation toward the light source within 20 s of exposure to near-infrared light, thus demonstrating the rapid photoresponsivity of rGO-PNH. Furthermore, the 4D-printed SBSR showcased effective grasping, lifting, and releasing of objects by mimicking the predatory behavior of starfish. This study would provide insights into the development of responsive materials in 4D printable bionic soft robots and their applications in areas such as biomimetic devices and artificial muscles

4D-Printed Bionic Soft Robot with Superior Mechanical Properties and Fast Near-Infrared Light Response

Inspired by natural organisms, a four-dimensional (4D)-printed starfish-like bionic soft robot (SBSR) was effectively prepared by integrating three-dimensional (3D) printing with smart hydrogels. The body of the SBSR is composed of a reduced graphene oxide-poly(N-isopropylacrylamide) hydrogel (rGO-PNH) with superior mechanical properties. In addition, the enhanced photothermal conversion effect was obtained by the reduction of graphene oxide nanosheets after the 3D printing process. Cylindrical actuators prepared using rGO-PNH exhibited bending and orientation toward the light source within 20 s of exposure to near-infrared light, thus demonstrating the rapid photoresponsivity of rGO-PNH. Furthermore, the 4D-printed SBSR showcased effective grasping, lifting, and releasing of objects by mimicking the predatory behavior of starfish. This study would provide insights into the development of responsive materials in 4D printable bionic soft robots and their applications in areas such as biomimetic devices and artificial muscles