In organic solar cells (OSCs), cathode interfacial materials are generally designed with highly polar groups to increase the capability of lowering the work function of cathode. However, the strong ...polar group could result in a high surface energy and poor physical contact at the active layer surface, posing a challenge for interlayer engineering to address the trade-off between device stability and efficiency. Herein, we report a hydrogen-bonding interfacial material, aliphatic amine-functionalized perylene-diimide (PDINN), which simultaneously down-shifts the work function of the air stable cathodes (silver and copper), and maintains good interfacial contact with the active layer. The OSCs based on PDINN engineered silver-cathode demonstrate a high power conversion efficiency of 17.23% (certified value 16.77% by NREL) and high stability. Our results indicate that PDINN is an effective cathode interfacial material and interlayer engineering via suitable intermolecular interactions is a feasible approach to improve device performance of OSCs.
Core–Shell Nanostructured Catalysts Zhang, Qiao; Lee, Ilkeun; Joo, Ji Bong ...
Accounts of chemical research,
08/2013, Volume:
46, Issue:
8
Journal Article
Peer reviewed
Novel nanotechnologies have allowed great improvements in the syn-thesis of catalysts with well-controlled size, shape, and surface properties. Transition metal nanostructures with specific sizes and ...shapes, for instance, have shown great promise as catalysts with high selectivities and relative ease of recycling. Researchers have already demonstrated new selective catalysis with solution-dispersed or supported-metal nanocatalysts, in some cases applied to new types of reactions. Several challenges remain, however, particularly in improving the structural stability of the catalytic active phase. Core–shell nanostructures are nanoparticles encapsulated and protected by an outer shell that isolates the nanoparticles and prevents their migration and coalescence during the catalytic reactions. The synthesis and characterization of effective core–shell catalysts has been at the center of our research efforts and is the focus of this Account. Efficient core–shell catalysts require porous shells that allow free access of chemical species from the outside to the surface of nanocatalysts. For this purpose, we have developed a surface-protected etching process to prepare mesoporous silica and titania shells with controllable porosity. In certain cases, we can tune catalytic reaction rates by adjusting the porosity of the outer shell. We also designed and successfully applied a silica-protected calcination method to prepare crystalline shells with high surface area, using anatase titania as a model system. We achieved a high degree of control over the crystallinity and porosity of the anatase shells, allowing for the systematic optimization of their photocatalytic activity. Core–shell nanostructures also provide a great opportunity for controlling the interaction among the different components in ways that might boost structural stability or catalytic activity. For example, we fabricated a SiO2/Au/N-doped TiO2 core-shell photocatalyst with a sandwich structure that showed excellent catalytic activity for the oxidation of organic compounds under UV, visible, and direct sunlight. The enhanced photocatalytic efficiency of this nanostructure resulted from an added interfacial nonmetal doping, which improved visible light absorption, and from plasmonic metal decoration that enhanced light harvesting and charge separation. In addition to our synthetic efforts, we have developed ways to evaluate the accessibility of reactants to the metal cores and to characterize the catalytic properties of the core–shell samples we have synthesized. We have adapted infrared absorption spectroscopy and titration experiments using carbon monoxide and other molecules as probes to study adsorption on the surface of metal cores in metal oxide–shell structures in situ in both gas and liquid phases. In particular, the experiments in solution have provided insights into the ease of diffusion of molecules of different sizes in and out of the shells in these catalysts.
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Promising catalytic activity from molybdenum disulfide (MoS2) in the hydrogen evolution reaction (HER) is attributed to active sites located along the edges of its two-dimensional layered crystal ...structure, but its performance is currently limited by the density and reactivity of active sites, poor electrical transport, and inefficient electrical contact to the catalyst. Here we report dramatically enhanced HER catalysis (an electrocatalytic current density of 10 mA/cm2 at a low overpotential of −187 mV vs RHE and a Tafel slope of 43 mV/decade) from metallic nanosheets of 1T-MoS2 chemically exfoliated via lithium intercalation from semiconducting 2H-MoS2 nanostructures grown directly on graphite. Structural characterization and electrochemical studies confirmed that the nanosheets of the metallic MoS2 polymorph exhibit facile electrode kinetics and low-loss electrical transport and possess a proliferated density of catalytic active sites. These distinct and previously unexploited features of 1T-MoS2 make these metallic nanosheets a highly competitive earth-abundant HER catalyst.
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Bioactive materials are a kind of materials with unique bioactivities, which can change the cellular behaviors and elicit biological responses from living tissues. Bioactive materials came into the ...spotlight in the late 1960s when the researchers found that the materials such as bioglass could react with surrounding bone tissue for bone regeneration. In the following decades, advances in nanotechnology brought the new development opportunities to bioactive nanomaterials. Bioactive nanomaterials are not a simple miniaturization of macroscopic materials. They exhibit unique bioactivities due to their nanoscale size effect, high specific surface area, and precise nanostructure, which can significantly influence the interactions with biological systems. Nowadays, bioactive nanomaterials have represented an important and exciting area of research. Current and future applications ensure that bioactive nanomaterials have a high academic and clinical importance. This review summaries the recent advances in the field of bioactive nanomaterials, and evaluate the influence factors of bioactivities. Then, a range of bioactive nanomaterials and their potential biomedical applications are discussed. Furthermore, the limitations, challenges, and future opportunities of bioactive nanomaterials are also discussed.
In this review, we summary the recent advances of bioactive nanomaterials, and discuss the influence factors of bioactivities including the physical structure of bioactive nanomaterials, surface properties, and nanotopography. Then, a range of bioactive nanomaterials, including inorganic nanomaterials, carbon‐based nanomaterials, polymeric nanomaterials, and supramolecular‐based nanomaterials are discussed. In addition, we also introduce several typical applications of bioactive nanomaterials, including wound healing, cancer therapy, neurodegenerative disease therapy, and biocatalyst.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Many different iron oxide nanoparticles have been evaluated over the years, for a wide variety of biomedical applications. We here summarize the synthesis, surface functionalization and ...characterization of iron oxide nanoparticles, as well as their (pre-) clinical use in diagnostic, therapeutic and theranostic settings. Diagnostic applications include liver, lymph node, inflammation and vascular imaging, employing mostly magnetic resonance imaging but recently also magnetic particle imaging. Therapeutic applications encompass iron supplementation in anemia and advanced cancer treatments, such as modulation of macrophage polarization, magnetic fluid hyperthermia and magnetic drug targeting. Because of their properties, iron oxide nanoparticles are particularly useful for theranostic purposes. Examples of such setups, in which diagnosis and therapy are intimately combined and in which iron oxide nanoparticles are used, are image-guided drug delivery, image-guided and microbubble-mediated opening of the blood-brain barrier, and theranostic tissue engineering. Together, these directions highlight the versatility and the broad applicability of iron oxide nanoparticles, and indicate the integration in future medical practice of multiple iron oxide nanoparticle-based materials.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Nanoparticles of nickel phosphide (Ni2P) have been investigated for electrocatalytic activity and stability for the hydrogen evolution reaction (HER) in acidic solutions, under which proton exchange ...membrane-based electrolysis is operational. The catalytically active Ni2P nanoparticles were hollow and faceted to expose a high density of the Ni2P(001) surface, which has previously been predicted based on theory to be an active HER catalyst. The Ni2P nanoparticles had among the highest HER activity of any non-noble metal electrocatalyst reported to date, producing H2(g) with nearly quantitative faradaic yield, while also affording stability in aqueous acidic media.
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A range of amphiphilic polymers with diverse macromolecular architectures has been developed and incorporated into films and coatings with potential for marine antibiofouling applications, without ...resorting to addition of currently used biocidal, toxic agents. Novel “green” chemical technologies employ different building blocks to endow the polymer film with surface activity, functionality, structure, and reconstruction according to the outer environment as a result of a tailored amphiphilic character of the polymer platform. We emphasise how these features can interplay and add synergistically to affect antifouling and fouling‐release against common, widespread marine micro‐ and macro‐fouling organisms.
Amphiphilic polymers with diverse macromolecular architectures have been developed as low environmental impact coatings to combat marine biofouling. These novel “green” technologies employ different building blocks to endow the polymer film with surface activity, functionality, structure, and reconstruction as a result of a tailored amphiphilic character of the polymer platform.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
By combining metal nodes with organic linkers we can potentially synthesize millions of possible metal–organic frameworks (MOFs). The fact that we have so many materials opens many exciting avenues ...but also create new challenges. We simply have too many materials to be processed using conventional, brute force, methods. In this review, we show that having so many materials allows us to use big-data methods as a powerful technique to study these materials and to discover complex correlations. The first part of the review gives an introduction to the principles of big-data science. We show how to select appropriate training sets, survey approaches that are used to represent these materials in feature space, and review different learning architectures, as well as evaluation and interpretation strategies. In the second part, we review how the different approaches of machine learning have been applied to porous materials. In particular, we discuss applications in the field of gas storage and separation, the stability of these materials, their electronic properties, and their synthesis. Given the increasing interest of the scientific community in machine learning, we expect this list to rapidly expand in the coming years.
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