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Evaluation of laser-induced carbons with concentric graphitic layers for highly durable and adaptable at low humidity
摘要： Laser-induced carbons, so-called onion-like carbon (OLC), were investigated for enhanced oxygen reduction reaction activity, excellent durability of catalysts on carbon supports, and adaptability at a low relative humidity (44% RH). OLC nanoparticles were obtained by laser irradiation of ethylene with different reaction positions. The residence time and energy distribution at a reaction zone lead to the formation of nano-carbons with graphitic shells. As a robust support compared to commercial carbon black (XC), the OLC nanoparticle consisting of concentric graphitic layers is fabricated and its structure with sp hybridizations helps strong interactions between Pt atoms and π-bond of OLC nanoparticles, preventing the surface migration of Pt atoms, resulting in enhanced durability in long-term operations. It leads that the downshift of Pt d-band center at Pt nanocatalysts on OLC shells structures reduces the adsorption strength of surface oxygen species, enhancing ORR activity. Compared to the Pt/XC, the performance of Pt/OLC nanocatalyst shows 1.27 times more active in low humidity conditions, and 1.36 times more active and durable after long-term operating in extreme conditions occurring carbon corrosion levels. These results exhibit that the Pt/OLC catalyst is expected to generate an incredible level of synergy for enhanced activity and durability.
关键词： Durability,Graphitic layers,Laser irradiation,Onion-like carbons
更新于2025-09-12 10:27:22
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Factors contributing to degradation of organic photovoltaic cells
摘要： The performance of organic photovoltaic (OPV) cells has considerably improved over the past decade, and now exceeds an energy conversion efficiency of 10%, the benchmark for practical use. One factor contributing to this increase is the development of π-conjugated linear acceptor molecules as alternatives to fullerene derivatives. Although conversion efficiency is an important issue for practical applications, device stability is also necessary for commercialization of OPV technologies. To date, long-term stability has been examined in OPV devices based on fullerenes. However, the factors involved in performance degradation remain poorly understood. It is difficult to address this problem because of the multilayer nature of the devices and many factors involved in degradation. In recent OPV devices based on π-conjugated molecules as acceptors, there have been few reports on stability under continuous light irradiation. Ensuring the stability of the π-conjugated molecules under illumination and electrical operation is critical for achieving practical use of OPV devices. In this paper, we comprehensively analyzed OPV devices based on EH-IDTBR as an acceptor material. We identified a decrease in OPV performance of approximately 50% under 100-hour light irradiation, which we attribute to increased resistance of the organic semiconductor layer. The increase in resistance was caused by a decrease in the number of carriers, suggesting that structural changes in the EH-IDTBR molecule are an important factor affecting degradation.
关键词： Durability,impedance measurement,organic photovoltaic,stability,MALDI-TOF-MS
更新于2025-09-11 14:15:04
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Durable, Optically Transparent, Superhydrophobic Polymer Films
摘要： Transparent and superhydrophobic free-standing films would be useful for extending non-wetting properties to optical applications especially those exposed to flowing water. However two challenges, transparency and durability, have proven difficult to overcome. Although a high degree of surface roughness is essential to sustain droplets of water in the Cassie state, this same roughness can lead to significant scattering and loss of optical clarity. Reducing roughness to a length scale below ? the wavelength of light reduces scattering, but can result in loss of durability. In this paper we describe a novel and simple lamination approach for treating free-standing films to become superhydrophobic, with high transparency and durability, by partially embedding hydrophobic silica nanoparticles into the surface of a cyclic olefin polymer (COP) film. Partial embedding insures that the particles are firmly adhered while their nano-scale roughness is exposed, resulting in excellent superhydrophobicity (contact angles >160° and roll off angle <10°), high transparency (over 87% transmission at 500 nm) and durability under flowing water (>6 hours at volumetric flow rate of 70 liters·min-1). The effect of processing parameters including the particle coating thickness and lamination conditions on the optical properties, hydrophobicity as well as mechanical durability of films are systematically studied.
关键词： wetting,optical transmittance,surface morphology,Superhydrophobicity,durability,lamination
更新于2025-09-10 09:29:36
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Stone/Coating Interaction and Durability of Si-Based Photocatalytic Nanocomposites Applied to Porous Lithotypes
摘要： The use of hybrid nanocoatings for the protection of natural stones has received increasing attention over the last years. However, the interaction of these materials with stones and, in particular, its modification resulting from the blending of nanoparticles and matrices, are yet little explored. In this work, the interaction of two nanocomposite coatings (based on alkylalkoxysilane matrices and TiO2 nanoparticles in water and 2-propanol) with two different porous stones is examined in detail by comparing their absorption behaviour and protection performance with those of the respective TiO2-free matrices. It is shown that the protective effectiveness of both matrices is not negatively affected by the presence of TiO2, as the desired water barrier effect is retained, while a significant photocatalytic activity is achieved. The addition of titania leads to a partial aggregation of the water-based matrix and accordingly reduces the product penetration into stones. On the positive side, a chemical interaction between titania and this matrix is observed, probably resulting in a greater stability of nanoparticles inside the protective coating. Moreover, although an effect of TiO2 on the chemical stability of matrices is observed upon UV light exposure, the protective performance of coatings is substantially maintained after ageing, while the interaction between matrices and nanoparticles results in a good retention of the latter upon in-lab simulated rain wash-out.
关键词： UV ageing,stone protection,water-repellency,photo-oxidative degradation,durability,artificial rain,photocatalysis,TiO2 nanoparticles,alkylalkoxysilane
更新于2025-09-09 09:28:46
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Nickel foam–caged Ag-Au bimetallic nanostructure as a highly rugged and durable SERS substrate
摘要： A three-dimensional nickel foam (NF) caging Ag-Au bimetallic nanostructure (Ag-Au@NF) has been demonstrated as a highly rugged and sensitive surface-enhanced Raman scattering (SERS) substrate. The main concept employed in designing this substrate was the protection of SERS-active nanostructures by holding them within a sturdy frame. For this purpose, NF was readily chosen as a strong porous frame to secure the internal nanostructures owing to its excellent structural strength and ability to easily incorporate analytes due to its porous structure. The next issue was the construction of stable and SERS-e?cient nanostructures within the NF frame. To meet this need, an Ag-Au bimetallic nanostructure was chosen, combining the high SERS e?ciency of Ag and the good surface stability of Au. To fabricate the Ag-Au nanostructure, ?rst a Sn-Ag alloy was constructed on the NF frame by means of electrodeposition (producing Sn-Ag@NF) and then Sn was selectively leached from the alloy by means of free corrosion in NaOH solution (producing Ag@NF). This selective leaching was adopted to make the surface rough to enhance the SERS e?ciency in the ?nal substrate. Finally, Au was incorporated into the Ag@NF by means of a galvanic replacement reaction (producing Ag-Au@NF). The use of Ag-Au@NF enabled identi?cation of rhodamine 6G at concentrations as low as 0.1 nM. The Ag-Au@NF substrates were rugged, showing small Raman signal drops after 100 cycles of sandpaper abrasion or 30 min of sonication. Also, the signal decrease was only 4.26% upon 3 days of exposure to ambient air without special care. Overall, the Ag-Au@NF developed herein shows practical merits for adoption in routine and ?eld SERS analyses.
关键词： Surface enhanced Raman scattering,High durability,Ag-Au nanostructure,Porous structure,Nickel foam
更新于2025-09-09 09:28:46
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AIP Conference Proceedings [Author(s) SolarPACES 2017: International Conference on Concentrating Solar Power and Chemical Energy Systems - Santiago, Chile (26–29 September 2017)] - Hydrophilic anti-soiling coating for improved efficiency of solar reflectors
摘要： The reflector is the first key component in the energy conversion process of concentrating solar technologies as any solar radiation that is not reflected by the mirror in the direction of the receiver is lost to the system. Due to the outdoor exposure, solar reflectors are subjected to constant soiling deposition (including dust, sand and/or dirtiness), which severely decreases the output power of the solar concentrating collectors, as it reduces the amount of radiation that can be reflected towards the receiver (associated to the absorption and scattering effects of light). Most of the Concentrating Solar Power (CSP) plants are installed in regions of high Direct Normal Irradiance (DNI) with arid and semi-arid climate, involving the existence of an important amount of dust and sand in the ambient. Collector cleanliness represents one of the most costly expenses of the solar-plant operation and maintenance (O&M). Consequently, minimizing this cost is an important issue for the solar-plant economic feasibility. Anti-soiling coatings deposited on the surface of silvered-glass reflectors are a powerful tool that can help in repelling all sort of dust, sand and particles. This technological solution presents the following benefits: (i) the maintenance cost is driven down by reducing washing times, (ii) the water consumption is drastically diminished and (iii) the efficiency is increased since the average reflectance of the solar field remains higher. This work presents the behavior of a new anti-soiling coating with improved durability and high efficiency.
关键词： durability,anti-soiling coating,solar reflectors,efficiency,hydrophilic
更新于2025-09-04 15:30:14