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Flexible hygroelectric generators (HEGs) that derive affordable and sustainable electricity power from omnipresent moisture are promising candidates for smart textile electronics. However, the desired compatibility of high output current and continuous operating voltage is still challenging for wearable HEGs to meet the ever-increasing nanotechnological requirements. Herein, we rationally design and finely synthesize conductive carbonized silk fabrics with in situ growth of SnO/SnO 2 nanosheet arrays, which are successfully employed to fabricate high-efficiency wearable HEGs with a maximal power density of 26.66 μW·cm−2 by sandwiching with MXene/cotton fabrics and Al electrodes. Impressively, the vertically interlaced SnO/SnO 2 nanosheet arrays supply abundant nanofluidic channels for rapid water diffusive flow with a high flow potential. Combined with the excellent moisture absorption and retention of MXene/cotton textiles, these prepared HEGs process sustained voltage and current outputs of 0.932 V and 0.434 mA over 20,000 s. These flexible HEGs are capable of application in self-powered sensors and micro power supplies, delivering a fresh strategy for the rational design of high-performance and sustainable textile-based electronics. [Display omitted] • A hygroelectric generator based on nanofluidic channels toward was developed. • The vertically interlaced SnO/SnO 2 nanosheet arrays supply abundant nanofluidic channels for a high flow potential. • The asymmetric fabrics structure incudes a proton concentration gradient for the enables charge separation. • These textile-based HEGs demonstrate an excellent performance with a maximal power density of 26.66 μW·cm−2. [ABSTRACT FROM AUTHOR]

Abstract Sufficient swelling pressure of compacted bentonite upon wetting is necessary to provide long-term stability to an engineered barrier system under conditions of thermal gradient and variable water chemistry in a high-level radioactive waste repository. To investigate the combined thermal and saline effects on the swelling pressure of Gaomiaozi (GMZ) bentonite, constant-volume swelling pressure tests were performed on densely compacted specimens inundated with deionized water, NaCl, and CaCl 2 solutions at 20 °C and 60 °C. The results indicate that high temperature and saline solutions decrease the swelling pressure. Crystalline swelling dominates the constant-volume swelling of densely compacted bentonite. For a given cation type, a higher temperature or higher solution concentration resulted in a lower swelling pressure. The decreasing surface potential and increasing osmotic suction with solution concentration both weaken the clay swelling. The effects of temperature on the swelling pressure are explained by the role of the lattice contraction. The degeneration of the interlamellar adsorbed water at high temperature weakens the crystalline swelling. The effects of cation types are interpreted by their difference in chemical activity. Ca2+ ions possess higher exchange capacity and larger hydrated radius than those of the Na+ ions. When densely compacted Na-bentonite is wetted with CaCl 2 solution, the possible change of the interlamellar cations from Na+ to Ca2+ ions would promote the crystalline swelling. The osmotic suction imposed by CaCl 2 solution may offset the role of the cation exchange to a small extent. The effect of temperature on the swelling pressure exceeds that of the cation types. For a given solution concentration, the specimen wetted with NaCl solution developed lower swelling pressure than that with CaCl 2 solution at 20 °C, whereas the opposite tendency appeared at 60 °C. In addition, specimens saturated with deionized water and NaCl solution at 20 °C obtained insignificant difference in pore size distribution, whereas identifiable differences in pore size distribution occured at 60 °C. The combined thermal and saline effects on the swelling pressure may be explained by the role of the lattice contraction at varied clay structure. When CaCl 2 solution is used, the quasicrystals contain more montmorillonite layers than the case of the NaCl solution. The role of the lattice contraction at high temperature is expected to decrease the swelling pressure to a greater degree in the case of the CaCl 2 solution. The remarkable increase in the osmotic suction at high temperature and high solution concentration could also enlarge the decrease in the swelling pressure. These conjectures, however, still require quantitative interpretations via microscopic tests such as X-ray powder diffraction tests on bulk samples. Highlights • High temperature preferentially dominates crystalline swelling. • High temperature has greater effects on PSD. [ABSTRACT FROM AUTHOR]

Knowledge of the mechanical properties of compacted bentonite is essential to assessing the performance of an engineered barrier system in a high-level radioactive waste repository. In this study, direct shear tests and uniaxial compression tests were conducted on compacted Gaomiaozi bentonite with a dry density of 1.7 g/cm3 to investigate its stiffness and strength characteristics at various initial suction levels. Specimens were found to exhibit brittle failure within an initial suction range of 11–223 MPa. The peak shear strength and shear modulus were found to increase with increasing initial suction and to begin to decrease at an initial suction of 126 MPa. The residual shear strength was found to increase with increasing initial suction within 11–223 MPa. The uniaxial compressive strength and elastic modulus were found to increase with increasing initial suction and to begin to decrease at an initial suction of 62 MPa. Models were developed to predict the stiffness and strength of the specimens as a function of the initial suction and effective stress parameter (χ). For the peak shear strength, shear modulus, uniaxial compressive strength, and elastic modulus, using the degree of saturation (S r) and effective degree of saturation (S e) in place of χ produced the same trends which diverged from the test results at initial suction levels lower than 12 MPa and higher than 126 MPa. However, using S r and S e in place of χ reasonably reproduced the residual shear strength within an initial suction range of 11–223 MPa. In contrast, using (S r)α (S r raised to an exponent α) in place of χ reproduced the test results well. For the peak shear strength, shear modulus, uniaxial compressive strength, and elastic modulus, the simulations required a value of 2.4 for the α. For the residual shear strength, the best value of α was 1.0. Based on the testing method and model approach developed in this study, the evolution of the stiffness and strength of compacted bentonite along wetting and drying paths can be further explored. • Stiffness and strength were determined via direct shear and uniaxial compression tests. • Stiffness and strength were modeled using the effective stress parameter χ. • Peak strength and stiffness modeling requires α = 2.4 when using (S r)α as the χ. • Residual shear strength modeling requires α = 1.0 when using (S r)α as the χ. [ABSTRACT FROM AUTHOR]