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► Hydrophobic hollow silica nanoparticles (HSNs) were designed and synthesized. ► Hydrophobic HSNs were used to construct coatings by spray-coating. ► The coatings reached excellent ...superhydrophobicity after post-treatment at 150°C for 5h. ► The coatings were robust to both impact of water and acidic/basic droplets.
The present paper reports a novel, simple, and efficient approach to fabricate transparent superhydrophobic coatings on glass substrates by spray-coating stearic acid (STA) and 1H,1H,2H,2H-perflurooctyltriethoxysilane (POTS) co-modified hollow silica nanoparticles (SPHSNs), the surfaces of which were hydrophobic. The surface wettability of coatings was dependent on the conditions of post-treatment: the water contact angle of coating increased and then leveled off with increase in either the drying temperature or the drying time. When the coating was treated at 150°C for 5h, the water contact angle was as high as 160° and the sliding angle was lower than 1°, reaching excellent superhydrophobicity. They remained 159° and⩽1°, respectively, even after 3months storage under indoor conditions (20°C, 20%RH), demonstrating the long time stability of coating superhydrophobicity. The coating was robust both to the impact of water droplets (297cm/s) and to acidic (pH=1) and basic (pH=14) droplets. It showed good transparency in the visible-near infrared spectral range, and the maximum transmittance reached as high as 89%. Fourier transform infrared spectroscopy, transmission electron microscopy, differential scanning calorimetry, and thermogravimetric analysis were used to investigate the interactions among STA, POTS, and hollow silica nanoparticles (HSNs). Scanning electron microscopy and atomic force microscopy were used to observe and estimate the morphology and surface roughness of coatings. Optical properties were characterized by a UV–visible-near infrared spectrophotometer. Surface wettability was studied by a contact angle/interface system. The enhancement of hydrophobicity to superhydrophobicity by post-treatment was discussed based on the transition from the Wenzel state to the Cassie state.
This study reported a multi-functional Co
Fe
Ni
-MOF/NF catalyst for oxygen evolution reaction (OER), hydrogen evolution reaction (HER), and overall water splitting, which was synthesized via a novel ...shape-preserving two-step hydrothermal method. The resulting bowknot flake structure on NF enhanced the exposure of active sites, fostering a superior electrocatalytic surface, and the synergistic effect between Co, Fe, and Ni enhanced the catalytic activity of the active site. In an alkaline environment, the catalyst exhibited impressive overpotentials of 244 mV and 287 mV at current densities of 50 mA cm
and 100 mA cm
, respectively. Transitioning to a neutral environment, an overpotential of 505 mV at a current density of 10 mA cm
was achieved with the same catalyst, showing a superior property compared to similar catalysts. Furthermore, it was demonstrated that Co
Fe
Ni
-MOF/NF shows versatility as a bifunctional catalyst, excelling in both OER and HER, as well as overall water splitting. The innovative shape-preserving synthesis method presented in this study offers a facile method to develop an efficient electrocatalyst for OER under both alkaline and neutral conditions, which makes it a promising catalyst for hydrogen production by water splitting.
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•A facile dip-coating method was used to fabricate coatings.•The coatings showed excellent antireflection in the wavelength range of 400–2000nm.•The coatings were superhydrophobic ...after hydrophobic modification.
This paper reports a new design to fabricate broadband antireflective superhydrophobic coatings by versatile dip-coating of three silica-based sols: silica sol (below 10nm) prepared under acidic conditions (sol A), silica nanoparticle (ca. 25nm) suspension prepared by the Stöber method (sol B) and mesoporous silica nanoparticle (MSN) suspension, followed by chemical vapor deposition of 1H,1H,2H,2H-perfluorooctyltriethoxysilane. The maximum transmittance of coatings reached as high as 95.3% at the wavelength of 630nm, whereas the water contact angle was 153° with sliding angle ⩽5° by applying of the A2/B/MSN2 coating. The superhydrophobic A/B/MSN2 coating (water contact angle: 153°, sliding angle: ⩽5°) showed excellent antireflection in the wavelength range of 400–2000nm, especially in the wavelength range of 742–1573nm where the transmittance of glass substrate is significantly lower. Transmission electron microscopy was used to characterize the morphology of synthesized nanoparticles. Scanning electron microscopy and atomic force microscopy were used to observe the morphology and estimate the surface roughness of coatings. Optical properties were characterized by a UV–visible–near infrared spectrophotometer. Surface wettability was studied by a contact angle/interface system. The broadband antireflection of superhydrophobic A/B/MSN2 coating was discussed in detail.
Doping CeO2 with Y cations was achieved in this study using three strategies: doping only during the hydrothermal process (H-Y-doped CeO2), doping only during the impregnation process (I-Y-doped ...CeO2), and doping during both the hydrothermal and impregnation processes (H/I-Y-doped CeO2). During the three synthesis strategies of Y-doped CeO2, these Y ions could be incorporated into the CeO2 lattice in the +3 state while holding the cubic fluorite structure, and no impurity phases were detected. Pure CeO2 crystal itself contained a certain number of intrinsic VO defects, and Y-doping was beneficial for the creation of extrinsic VO defects. The relative concentrations of VO defects were quantified by the values of A592/A464 obtained from Raman spectra, which were 1.47, 0.93, and 1.16 for the H-Y-, I-Y-, and H/I-Y-doped CeO2, respectively, and were higher than that of the undoped one (0.67). Moreover, the OSCs of the three Y-doped CeO2 were enhanced, and the sequence of OSCs was: H-Y-doped CeO2 (0.372 mmol/g) > H/I-Y-doped CeO2 (0.353 mmol/g) > I-Y-doped CeO2 (0.248 mmol/g) > Undoped CeO2 (0.153 mmol/g); this result was in good agreement with the Raman spectroscopy results.
A cubic fluorite-type CeO2 with mesoporous multilayered morphology was synthesized by the solvothermal method followed by calcination in air, and its oxygen storage capacity (OSC) was quantified by ...the amount of O2 consumption per gram of CeO2 based on hydrogen temperature programmed reduction (H2–TPR) measurements. Doping CeO2 with ytterbium (Yb) and nitrogen (N) ions proved to be an effective route to improving its OSC in this work. The OSC of undoped CeO2 was 0.115 mmol O2/g and reached as high as 0.222 mmol O2/g upon the addition of 5 mol.% Yb(NO3)3∙5H2O, further enhanced to 0.274 mmol O2/g with the introduction of 20 mol.% triethanolamine. Both the introductions of Yb cations and N anions into the CeO2 lattice were conducive to the formation of more non-stoichiometric oxygen vacancy (VO) defects and reducible–reoxidizable Cen+ ions. To determine the structure performance relationships, the partial least squares method was employed to construct two linear functions for the doping level vs. lattice parameter and VO vs. OSC/SBET.
CeO2 is an important rare earth (RE) oxide and has served as a typical oxygen storage material in practical applications. In the present study, the oxygen storage capacity (OSC) of CeO2 was enhanced ...by doping with other rare earth ions (RE, RE = Yb, Y, Sm and La). A series of Undoped and RE–doped CeO2 with different doping levels were synthesized using a solvothermal method following a subsequent calcination process, in which just Ce(NO3)3∙6H2O, RE(NO3)3∙nH2O, ethylene glycol and water were used as raw materials. Surprisingly, the Undoped CeO2 was proved to be a porous material with a multilayered special morphology without any additional templates in this work. The lattice parameters of CeO2 were refined by the least–squares method with highly pure NaCl as the internal standard for peak position calibrations, and the solubility limits of RE ions into CeO2 were determined; the amounts of reducible–reoxidizable Cen+ ions were estimated by fitting the Ce 3d core–levels XPS spectra; the non–stoichiometric oxygen vacancy (VO) defects of CeO2 were analyzed qualitatively and quantitatively by O 1s XPS fitting and Raman scattering; and the OSC was quantified by the amount of H2 consumption per gram of CeO2 based on hydrogen temperature programmed reduction (H2–TPR) measurements. The maximum OSC of CeO2 appeared at 5 mol.% Yb–, 4 mol.% Y–, 4 mol.% Sm– and 7 mol.% La–doping with the values of 0.444, 0.387, 0.352 and 0.380 mmol H2/g by an increase of 93.04, 68.26, 53.04 and 65.22%. Moreover, the dominant factor for promoting the OSC of RE–doped CeO2 was analyzed.
A porous CeO2 was synthesized following the addition of guanidine carbonate to a Ce3+ aqueous solution, the subsequent addition of hydrogen peroxide and a final hydrothermal treatment. The optimal ...experimental parameters for the synthesis of porous CeO2, including the amounts of guanidine carbonate and hydrogen peroxide and the hydrothermal conditions, were determined by taking the adsorption efficiency of acid orange 7 (AO7) dye as the evaluation. A template−free hydrothermal strategy could avoid the use of soft or hard templates and the subsequent tedious procedures of eliminating templates, which aligned with the goals of energy conservation and emission reduction. Moreover, both the guanidine carbonate and hydrogen peroxide used in this work were accessible and eco−friendly raw materials. The porous CeO2 possessed rapid adsorption capacities for AO7 dye. When the initial concentration of AO7 was less than 130 mg/L, removal efficiencies greater than 90.0% were obtained, achieving a maximum value of 97.5% at AO7 = 100 mg/L and CeO2 = 2.0 g/L in the first 10 min of contact. Moreover, the adsorption–desorption equilibrium between the porous CeO2 adsorbent and the AO7 molecule was basically established within the first 30 min. The saturated adsorption amount of AO7 dye was 90.3 mg/g based on a Langmuir linear fitting of the experimental data. Moreover, the porous CeO2 could be recycled using a NaOH aqueous solution, and the adsorption efficiency of AO7 dye still remained above 92.5% after five cycles. This study provided an alternative porous adsorbent for the purification of dye wastewater, and a template−free hydrothermal strategy was developed to enable the design of CeO2−based catalysts or catalyst carriers.
A facile dip-coating approach was developed to fabricate visible/near-IR antireflective and superhydrophobic coatings on glass substrates from hydrophobic hexamethyldisilazane (HMDS)-modified hollow ...silica nanoparticles (HMDS-HSNs) and poly(methyl methacrylate) (PMMA). While the coated glass substrates showed greatly enhanced transmittance in the visible/near-IR range as compared with uncoated glass substrates, water droplets could roll easily and quickly off the coated surfaces. For the coating prepared using a suspension of 1.00 wt% PMMA and 0.50 wt% HMDS-HSNs, the water contact angle (WCA) of the coating was as high as 163 degree with a sliding angle (SA) of less than or equal to 1 degree , and the coated glass substrate showed excellent antireflection in the visible/near-IR spectral range with a maximum transmittance of 92.6%. The average transmittance of the coated glass substrate increased to 91.5% as compared to that of the uncoated glass substrate (88.2%) in the spectral range of 573-2500 nm. In particular, in the spectral range of 850-1200 nm, the coated glass substrate (ca.91%) exhibited an increase of nearly 5% in transmittance as compared with the uncoated glass substrate (ca.86%). Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and atomic force microscopy (AFM) were used to observe the morphology and structure of the nanoparticles and the coated surfaces. The effects of PMMA and HMDS-HSN concentrations were also discussed on the basis of experimental observations.
Hydrogen energy, known for its high energy density, environmental friendliness, and renewability, stands out as a promising alternative to fossil fuels. However, its broader application is limited by ...the challenge of efficient and safe storage. In this context, solid-state hydrogen storage using nanomaterials has emerged as a viable solution to the drawbacks of traditional storage methods. This comprehensive review delves into the recent advancements in nanomaterials for solid-state hydrogen storage, elucidating the fundamental principles and mechanisms, highlighting significant material systems, and exploring the strategies of surface and interface engineering alongside catalytic enhancement. We also address the primary challenges and provide future perspectives on the development of nanomaterial-based hydrogen storage technologies. Key discussions include the role of nanomaterial size effects, surface modifications, nanocomposites, and nanocatalysts in optimizing storage performance.
Superhydrophobic self-cleaning antireflective coatings were fabricated on Fresnel lenses by integrating solid silica nanoparticles (SSNs) and stearic acid (STA) and ...1H,1H,2H,2H-perflurooctyltriethoxysilane (POTS) co-modified hollow silica nanoparticles (SPHSNs) viaspin- and spray-assembly without any high temperature pre- or post-treatment. Transmission electron microscopy (TEM) was used to observe the morphology and structure of nanoparticles. Transmission spectra were recorded using a UV-Vis-NIR spectrophotometer. Surface wettability was studied by an automatic contact angle/interface system. Condensation performance of the Fresnel lenses was studied by measuring the focal length and the powers before and after being focused. The (SSNs) sub(1)/(SPHSNs) sub(2) coating turned out to simultaneously demonstrate excellent superhydrophobic self-cleaning and antireflective properties, which has a maximum transmittance of 99.0% and average transmittance of 98.5% in the wavelength range of 400-800 nm, and the condensing efficiency of the coated Fresnel lens has also been significantly improved. The surface morphology and structure of coatings were examined by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The effects of surface morphology and structure on the optical and wetting properties of coatings were also discussed. The density of SPHSNs on the coating surface was considered to significantly influence both the light transmission and hydrophobicity of coated Fresnel lenses.
