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Wearable hybrid energy harvesters show enormous potential for supplying power to wearable electronics since they circumvent the issue of discontinuous source energy of single energy harvesters and thereby supply more available energy. The hybridization of triboelectric nanogenerators (TENGs) and biofuel cells (BFCs) is promising; however, there are two major challenges. First, the two energy harvesters' outputs are severely mismatched, but optimized power management and design principles have not yet been demonstrated. Second, previously reported devices are based on planar structures and lack breathability. Here, we develop a breathable and woven hybrid energy harvester (BWHEH) that is knitted with a textile TENG and fiber BFCs. A power management circuit is specially designed to match and optimize the output direct current power supply, which can enlarge the output power by ∼46.1 times, significantly lowering the effective internal impedance of the power source and improving the power delivery for common wearable loading conditions. The design principles of the power management for the TENG–BFC hybrid are thoroughly revealed. The wearable BWHEH self-charging power system can sustainably power various portable electronics by harvesting biomechanical and biochemical energy. This work provides a new route for energy harvesting and offers fundamental guidance for high-power hybrid energy harvesters. [Display omitted] • A breathable and woven hybrid energy harvester (BWHEH) is developed by the knitting of a T-TENG and F-BFCs. • A power management circuit is specifically designed to optimize the BWHEH's output power. • The BWHEH with power management can sustainably drive various common electronics by harvesting human energy. [ABSTRACT FROM AUTHOR]

• Analysing spatial effects of trees is critical for improving forest management. • This study explored spatial effects of trees using biomass data in Yunnan, China. • The significant spatial autocorrelations vary with stands, components, and distances. • The stands' spatial heterogeneity increased with distance and stabilised at 10 m. The trees in a given stand compete with each other for light, water and nutrients, producing spatial effects. To understand spatial effects, it is critical to characterise the spatial distributions and patterns of the aboveground biomass (AGB) of individual trees and the biomass of their components (stem, bark, branches and foliage). This study investigated the spatial effects by examining the AGB of individual trees and the biomass of their components in the context of typical sub-tropical tree species in Yunnan, China, including a Pinus kesiya var. langbianensis natural forest (PN), a Pinus kesiya var. langbianensis plantation (PP), and a Eucalyptus spp. plantation (EP), using datasets for three clear-cutting plots. Ripley's L function was employed to identify the spatial distributions and patterns of the AGB of individual trees and the biomass of their components. Then, Global and Local Moran's I indices were utilised to analyse spatial autocorrelation, with Intra-group variance being calculated to quantify spatial heterogeneity. This led to following findings. Firstly, with increasing distance, the spatial heterogeneity of the three stands increased before stabilising at a distance of 10 m. Secondly, excluding bark, all components of the tree biomass in the PN stand exhibited significant dispersion. In contrast, all the components in the PP stand showed significant dispersion. The spatial distributions and patterns of trees and their biomass in the EP stand indicated the coexistence of clustering and dispersion. Moreover, the significant spatial autocorrelations of tree AGB and components biomass could be noticed but depending on the stands, components and distances. These findings provide theoretical support for sustainable forest management based on biomass and carbon stocks. [ABSTRACT FROM AUTHOR]

[Display omitted] • A facile strategy is proposed to prepare high performance organohydrogel with multifunctional properties, • Gelatin/PAM/DMSO/Na 2 SO 4 (GPDN) organohydrogels displayed splendid mechanical properties. • GPDN showed the high anti-fatigue property over 1000 tensile cycles at a fixed strain of 300% without obvious plastic deformation. • GPDN based sensor could detect multiple external stimuli with high sensitivity (gauge factor of 7.13) and favorable cyclic stability. High mechanical stability during cyclic tensile loading–unloading courses is critical for the actual applications of hydrogels in the wearable electronic equipment and human–machine interfaces. However, the conventional hydrogels prominently confront poor mechanical performances and are subjected to fatigue fracture under continuous loading–unloading cycles. Herein, a facile strategy is proposed to prepare a hybrid physically and chemically crosslinked double network organohydrogel. The gelatin forms the physically cross-linked network through sol–gel transition and salting-out effect. The poly(acrylamide) (PAM) chains construct the chemically cross-linked network. The prepared gelatin/PAM/DMSO/Na 2 SO 4 (GPDN) organohydrogels displayed splendid mechanical properties. Furthermore, GPDN organohydrogels showed the high anti-fatigue property over 1000 tensile cycles at the fixed strain of 300% without obvious plastic deformation. In particular, the GPDN organohydrogel displayed high ionic conductivity and could be used as the strain sensor to detect multiple external stimuli (tension, compression, and bending) with high sensitivity (gauge factor of 7.13) and favorable cyclic stability. [ABSTRACT FROM AUTHOR]

Carbon materials with hierarchical porous structure and heteroatom-doping have gained extensive attention as promising electrode for supercapacitors. In this study, we report a facile approach which involves only one step of calcination and washing treatment to prepare nitrogen-doped carbon material with tunable pore structure. This carbon material was derived from chitosan employing the blend of potassium nitrate and hexahydrate magnesium nitrate as the active agent. By adjusting the calcination temperature and active agents, the morphology and pore structure of the material can be effectively controlled. By means of this approach, the three-dimensional hierarchical porous carbon possesses a large specific surface area of 922 m2 g−1, and abundant nitrogen and oxygen functional groups. Benefiting from these advantages, the final product shows high specific capacitance of 225.3 F g−1 in a three-electrode system at 1 A g−1, good cycle stability with 88% capacity retention after 10000 cycles at 5 A g−1. Additionally, the constructed symmetric two-electrode supercapacitor shows remarkable specific energy of 10.46 Wh kg−1 with the specific power of 500.08 W kg−1. It also showed excellent electrochemical performance in PVA/KOH hydrogel electrolyte with 70.8 F g−1 at the current density of 1 A g−1. [Display omitted] • This hierarchical porous carbon material was prepared from chitosan through one-step high-temperature carbonization. • The blend of potassium nitrate and magnesium nitrate was employed as the active agent. • The pore size of HPCMgK-600 mainly distributed in micro and mesopores at around 0.5 and 3.5 nm. • HPCMgK-600 displayed high performance as the electrode for supercapacitor. [ABSTRACT FROM AUTHOR]

In this work, the high-performance and flexible solid-state supercapacitors were fabricated based on poly(vinyl alcohol)(PVA)/NaCl/glycerol hydrogel electrolyte and activated carbon electrodes. A novel assembling method was proposed according to the formation properties of PVA/NaCl/glycerol hydrogel electrolyte. PVA/NaCl/glycerol hydrogel electrolyte could be quickly formed in a short time at room temperature. Thus the PVA/NaCl/glycerol solution was coated onto the activated carbon electrodes and the hydrogel electrolyte was in situ formed on the surface of the activated electrodes. Meanwhile, the PVA/NaCl/glycerol hydrogel electrolyte could retain outstanding flexibility and ionic conductivity at a low temperature, which makes the solid-state supercapacitor have excellent low-temperature tolerance. Thus, the electrochemical measurements of the assembled supercapacitor were performed at room temperature and a low temperature of −23 °C, respectively. The flexible supercapacitor can show an outstanding flexibility and electrochemical performance at −23 °C. Its specific capacitance can remain approximately 81.0% of its initial specific capacitance at room temperature and the capacitance retention could keep 90.5% of the initial capacitance retention at −23 °C. It also could be anticipated that this multifunctional flexible supercapacitor with the PVA/NaCl/glycerol hydrogel electrolyte would have broad applications in modern flexible energy storage device. [ABSTRACT FROM AUTHOR]