Solar energy-facilitated materials are promising to solve energy problems by converting clean solar energy to thermal energy. However, heat loss of photothermal materials still limits the photothermal conversion phenomenon. Herein, we designed bio-inspired hollow carbon microtubes (HCMTs) by one-step carbonization of renewable cotton fibers, which can avoid the complex preparation procedures of the template method. Similar to polar bears, the hollow construction can efficiently reduce heat loss, which improves the utilization of light and photothermal property. The HCMTs can be applied on a variety of substrates to obtain multifunctional photothermal protective coatings. The temperature of the coating can rapidly warm up to 97.7 °C under 1 kW/m 2 sun irradiation. In addition, the coatings show excellent superhydrophobic property (CA of 161.5 ± 0.9°), which can prevent the adhesion of the contaminant and maintain the long-time photothermal property of the surface. Also, the coating is able to withstand sandpaper abrasion, repeat tape-peeling, and tribological friction without losing superhydrophobic properties, indicating remarkable mechanical stability. Furthermore, the coating can withstand high-temperature calcination (400 °C), long-time UV radiation, and corrosive liquid erosion, which exhibits prominent chemical stability. More importantly, the combination of active deicing and passive antiicing of the coating can effectively prevent the formation and accumulation of ice on the surface. The outstanding environmental adaptability can greatly extend its lifespan and meet the long-term service conditions.
In this work, magnetic CuFe2O4/Ag nanoparticles activated by porous covalent organic frameworks (COF) was fabricated to evaluate the heterogenous reduction of 4-nitrophenol (4-NP). The core-shell CuFe2O4/Ag@COF was successfully prepared by polydopamine reduction of silver ions on CuFe2O4 nanoparticles, followed by COF layer condensation. By integrating the intrinsic characteristics of the magnetic CuFe2O4/Ag core and COF layer, the obtained nanocomposite exhibited features of high specific surface area (464.21 m2 g−1), ordered mesoporous structure, strong environment stability, as well as fast magnetic response. Accordingly, the CuFe2O4/Ag@COF catalyst showed good affinity towards 4-NP via π-π stacking interactions and possessed enhanced catalytic activity compared with CuFe2O4/Ag and CuFe2O4@COF. The pseudo-first-order rate constant of CuFe2O4/Ag@COF (0.77 min−1) is 3 and 5 times higher than CuFe2O4/Ag and CuFe2O4@COF, respectively. The characteristics of bi-catalytic CuFe2O4/Ag and the porous COF shell of CuFe2O4/Ag@COF made a contribution to improve the activity of 4-NP reduction. The present work demonstrated a facile strategy to fabricate COF-activated nano-catalysts with enhanced performance in the fields of nitrophenolic wastewater treatment.
A facile approach was successfully developed for synthesis of cellulose nanocrystals (CNC)-supported magnetic CuFe 2 O 4 @Ag@ZIF-8 nanospheres which consist of a paramagnetic CuFe 2 O 4 @Ag core and porous ZIF-8 shell. The CuFe 2 O 4 nanoparticles (NPs) were first prepared in the presence of CNC and dispersant. Ag NPs were then deposited on the CuFe 2 O 4 /CNC composites via an in situ reduction directed by dopamine polymerization (PDA). The CuFe 2 O 4 /CNC@Ag@ZIF-8 nanocomposite was characterized by TEM, FTIR, XRD, N 2 adsorption-desorption isotherms, VSM, and XPS. Catalytic studies showed that the CuFe 2 O 4 /CNC@Ag@ZIF-8 catalyst had much higher catalytic activity than CuFe 2 O 4 @Ag catalyst with the rate constant of 0.64 min −1 . Because of the integration of ZIF-8 with CuFe 2 O 4 /CNC@Ag that combines the advantaged of each component, the nanocomposites were demonstrated to have an enhanced catalytic activity in heterogeneous catalysis. Therefore, these results demonstrate a new method for the fabrication of CNC-supported magnetic core-shell catalysts, which display great potential for application in biocatalysis and environmental chemistry.Molecules 2020, 25, 124 2 of 15 More often, hybrid composites are fabricated through an in-situ method, where the templates have a high affinity towards metal ions that allows for the synthesis of metallic nanoparticles [8]. Cellulose nanocrystals (CNC) are derived from abundant cellulosic resources such as plants and microbial cellulose via sulfuric acid hydrolysis [9,10]. CNC have well-defined size and morphology, high specific surface area, high aspect ratio, high crystalline order, chirality, high mechanical strength, and controllable surface chemistry [11], which are appealing in a plethora of materials to catalytic applications. As reported in our previous research [12], the CuFe 2 O 4 /CNC nanocomposites show good dispersity and it has been suggested that the nanocomposites do catalyze 4-NP reduction.To further improve the catalytic activity, various core/shell-structured magnetic nanocatalysts have been applied in nanocatalysis [13][14][15][16]. The as-obtained CuFe 2 O 4 based core-shell nanocomposites showed excellent catalytic activity, magnetic separation, and magnetic carrying in nanocatalysis. Recently, the Ag modified magnetic composites have gained increasing attention because of the high catalytic activity of the Ag component, the good magnetic responsiveness of the magnetic core, and the relatively facile fabrication process [17][18][19]. Various noble metals, including Au, Pd, and Pt have been widely employed as catalysts for the reduction of 4-NP to 4-AP by NaBH 4 in aqueous media [20][21][22][23]. Moreover, Ag is more suitable for large-scale application than other noble metals (Au, Pd, and Pt) because of its low price [24]. Dopamine can self-polymerize under specific conditions to form a polydopamine (PDA) complex which has the ability of adhering onto the surface of various materials due to the strong stickiness [25][26][27] and the abundant catech...
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