Latent heat storage systems based on organic phase change materials (PCMs) are considered to be an efficient solar energy utilization strategy, but leakage vulnerability and insensitivity to sunlight of PCMs limit their further application in energy storage. In this work, a new hierarchical porous aerogel was constructed with the carbon intercalated halloysite nanotubes (CHNTs) as the assembly units for PCMs encapsulation to improve the load weight, stability and sunlight absorption. The CHNTs were first successfully synthesized through intercalation and carbonization, with the aim of increasing their specific surface area and sunlight absorption. Subsequently, the CHNTs/polyvinyl alcohol (PVA) aerogels with 3D honeycomb structure were prepared by self-assembly using a freeze-drying method, which can significantly promote the encapsulation ratio of lauric acid (LA) in the pores of both aerogels and CHNTs. The CHNTs can not only improve compressive strength of the aerogels and shape stability of the composite PCMs, but also enhance light absorption ability of the composites compared to pristine HNTs. As a support material, CHNTs aerogel (CHNP) loaded more than 92 wt% PCM (LA@CHNP) and exhibited an extremely high latent heat capacity (170.9 J/g). The LA@CHNP had good structural and thermal stability in 300 cycles without visible leakage. Besides, solar energy absorption increased from 43 % to 98 %, and the solar-to-thermal energy conversion efficiency increased to 95.88 %, which could be attributed to 3D porousness and carbon nanolayers of the CHNTs. We have successfully synthesized an eco-friendly and facile composite LA@CHNP, which will contribute to the design of advanced composites with excellent solar energy storage properties, and provide a new direction for the application of carbonized materials.
The traditional separator plays a significant role in rechargeable lithium-ion batteries due to the customized features that allow ions to transfer freely with low energy barriers. However, in the lithium–sulfur battery, the commercial separator shows feeble ability for promoting the conversion of accumulated long-chain polysulfides to the short-chain polysulfides on the surface of the cathode. In this work, a carbon-intercalated montmorillonite is designed to release the imprisoned capacity of the sulfur cathode by activating the accumulated long-chain polysulfides on the surface of the cathode. Benefiting from the advantages of carbon-intercalated montmorillonite, the lithium–sulfur battery achieves a high discharge capacity of 818 mAh g–1 over 300 cycles at a current density of 1 mA cm–2 with a sulfur loading of 2.6 mg cm–2. The systematic analyses by cyclic voltammetry and AC impedance reveal that the regulation of redox environment on the cathode surface by reducing the accumulated long-chain polysulfides to short-chain sulfides is a scalable solution for constructing the actual lithium–sulfur batteries.
Molybdenum disulfide serves as an ideal support for single atom catalysts (SACs), offering not only coordination elements but also abundant active sites, such as surface defects and vacancies. Herein, a novel Co-SAC (MoSO-Co-C) containing a four-coordinated configuration (Mo-Co-C 3 ) is designed and synthesized, in which the carbon intercalation is utilized to regulate sulfur vacancies for anchoring the Co atom. The introduction of Co atoms and C intercalation significantly enhances the E ads between catalyst and peroxymonosulfate (PMS), favoring the formation of metastable intermediates. The k obs of sulfamethoxazole (SMX) removal for MoSO-Co-C is 9.2 times and 1.8 times higher than those of catalysts without Co or C intercalation. SMX is removed mainly by electron transfer pathway, wherein SMX and PMS act on the same Co site of MoSO-Co-C, and electrons are transferred from SMX to MoSO-Co-C and eventually to PMS. The MoSO-Co-C demonstrated excellent SMX degradation in the diverse water matrices, and the removal efficiency of SMX maintained above 95 % after 72 h of continuous degradation. This study provides new insights into the design of transition metal-based SAC and in-depth understanding of PMS activation mechanism.
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