One-dimensional nanofibers can be transformed into hollow structures with larger specific surface area, which contributes to the enhancement of gas adsorption. We firstly fabricated Cu-doped In2O3 (Cu-In2O3) hollow nanofibers by electrospinning and calcination for detecting H2S. The experimental results show that the Cu doping concentration besides the operating temperature, gas concentration, and relative humidity can greatly affect the H2S sensing performance of the In2O3-based sensors. In particular, the responses of 6%Cu-In2O3 hollow nanofibers are 350.7 and 4201.5 to 50 and 100 ppm H2S at 250 °C, which are over 20 and 140 times higher than those of pristine In2O3 hollow nanofibers, respectively. Moreover, the corresponding sensor exhibits excellent selectivity and good reproducibility towards H2S, and the response of 6%Cu-In2O3 is still 1.5 to 1 ppm H2S. Finally, the gas sensing mechanism of Cu-In2O3 hollow nanofibers is thoroughly discussed, along with the assistance of first-principles calculations. Both the formation of hollow structure and Cu doping contribute to provide more active sites, and meanwhile a little CuO can form p—n heterojunctions with In2O3 and react with H2S, resulting in significant improvement of gas sensing performance. The Cu-In2O3 hollow nanofibers can be tailored for practical application to selectively detect H2S at lower concentrations.
A novel TiO 2 hydrogel cage model was built for the removal of methylene blue (MB), an organic pollutant. This TiO 2 hydrogel cage was prepared with the biomass materials of hydroxyethyl cellulose (HEC) and carboxymethyl cellulose (CMC), and this hydrogel cage structure was characterized by scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. The contents of the encased TiO 2 and its swelling properties with different CMC proportions of this hydrogel cage were studied to obtain a suitable crosslinking network structure and optimal synthesis conditions. Compared to an equivalent amount of pure TiO 2 , the much higher removal efficiency of MB with our prepared TiO 2 hydrogel cage was attributed to the synergistic effect of the photocatalytic degradation for TiO 2 and the adsorption enrichment for cellulose hydrogels. Furthermore, the adsorption kinetics of the intraparticle diffusion model were used to study the adsorption enrichment process of the TiO 2 hydrogel cage. In addition, on the basis of the results of photocatalytic degradation and recycling experiments, excellent performances with respect to self-cleaning, regenerative ability, and easy recovery, were shown for this HEC-TiO 2 -CMC cage material, which demonstrated ideal application potential for MB removal.
Due to their unique structure properties, most of the electrides that possess extra electrons locating in interstitial regions as anions are insulators. Metallic and superconducting electrides are very rare under ambient conditions. We systematically search possible compounds in Ca–S systems stabilized under various pressures up to 200 GPa, and investigate their crystal structures and properties using first-principles calculations. We predict a series of novel stoichiometries in Ca–S systems as potential superconductors, including P21/m Ca3S, P4mbm Ca3S, Pnma Ca2S, Cmcm Ca2S, Fddd CaS2, Immm CaS3 and C2/c CaS4. The P4mbm Ca3S phase exhibits a maximum T
c value of ∼20 K. It is interesting to notice that the P21/m Ca3S and Pnma Ca2S stabilized at 60 and 50 GPa behave as superconducting electrides with critical temperatures T
c of 7.04 K and 0.26 K, respectively. More importantly, our results demonstrate that P21/m Ca3S and Pnma Ca2S are dynamically stable at 5 GPa and 0 GPa, respectively, indicating a high possibility to be quenched to ambient condition or synthesized using the large volume press.
The conversion of solar power to hydrogen (H 2 ) energy efficiently encounters some obstacles due to the lack of superior catalysts and efficient catalytic approaches. Herein, three-dimensional/ two-dimensional (3D/2D) CuS/g-C 3 N 4 photothermal catalysts were obtained via an easy, one-step hydrothermal method after pyrolysis. The favorable heterojunction interface for H 2 production was constructed by snowflake-like CuS embedded in the graphite carbon nitride (g-C 3 N 4 ) nanosheets, leading to the acceleration of charge transfer and separation, decrease of charge transfer distance, and perfect realization of photothermal effects (PTEs) induced by nearinfrared (NIR) light. The 3D/2D CuS/g-C 3 N 4 catalyst presents a topmost H 2 -production rate (1422 μmol h −1 g −1 ) under dual wavelength (420 + 850 nm) and a moderate H 2 -production rate under 420 nm, which are 12-fold and 9-fold higher than pure g-C 3 N 4 , respectively, owing to a strong action from PTEs induced by NIR. The feasible NIR-enhanced photothermal catalysis is expected to apply in multifarious heat-assisted photocatalysis processes by designing multifunctional composites with super PTE and photocatalytic capacity.
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