Synergistic Ni-W Dimer Sites Induced Stable Compressive Strain for Boosting the Performance of Pt as Electrocatalyst for the Oxygen Reduction Reaction.

Alloying Pt catalysts with transition metal elements is an effective pathway to enhance the performance of oxygen reduction reaction (ORR), but often accompanied with severe metal dissolution issue, resulting in poor stability of alloy catalysts. Here, instead of forming traditional alloy structure, we modify Pt surface with a novel Ni-W dimer structure by the atomic layer deposition (ALD) technique. The obtained NiW@PtC catalyst exhibits superior ORR performance both in liquid half-cell and practical fuel cell compared with initial Pt/C. It is discovered that strong synergistic Ni-W dimer structure arising from short atomic distance induced a stable compressive strain on the Pt surface, thus boosting Pt catalytic performance. This surface modification by synergistic dimer sites offers an effective strategy in tailoring Pt with excellent activity and stability, which provides a significant perspective in boosting the performance of commercial Pt catalyst modified with polymetallic atom sites.

Robust fully controlled nanometer liquid layers for high resolution liquid-cell electron microscopy.

Liquid cell electron microscopy (LCEM) has long suffered from irreproducibility and its inability to confer high-quality images over a wide field of view. LCEM demands the encapsulation of the in-liquid sample between two ultrathin membranes (windows). In the vacuum environment of the electron microscope, the windows bulge, drastically reducing the achievable resolution and the usable viewing region. Herein, we introduce a shape-engineered nanofluidic cell architecture and an air-free drop-casting sample loading technique, which combined, provide robust bulgeless imaging conditions. We demonstrate the capabilities of our stationary approach through the study of in-liquid model samples and quantitative measurements of the liquid layer thickness. The presented LCEM method confers high throughput, lattice resolution across the complete viewing window, and sufficient contrast for the observation of unstained liposomes, paving the way to high-resolution movies of biospecimens in their near native environment.

Availability of Environmental Iron Influences the Performance of Biological Adhesives Produced by Blue Mussels.

Animals incorporate metals within the materials they manufacture, such as protective armor and teeth. Iron is an element used for adding strength and self-healing properties to load-bearing materials. Incorporation of iron is found beyond hard, brittle materials, even within the soft adhesive produced by marine mussels. Such findings suggest that the bioavailability of iron may have an influence on the properties of a biological material. Experiments were conducted using live mussels in which seawater iron levels were deficient, normal, or in excess of typical concentrations. The weakest adhesive strengths were produced in iron-deficient waters. Increasing seawater iron brought about more robust bonding. Changes in strengths correlated with varied adhesive morphology, color, and microstructural features, likely a result of variations in the degree of iron-induced protein cross-linking. This study provides the first whole animal scale data on how the manipulation of bioavailable iron influences the performance of a biological material. Changing ocean chemistries will alter the iron bioavailability when a decrease in pH shifts elemental speciation from particulate to dissolved, hindering the ability of filtering organisms to capture nutrients. These results show future implications of changing ocean chemistry as well as of the resulting abilities of marine organisms to construct essential materials.

Examining Potential Active Tempering of Adhesive Curing by Marine Mussels.

Mussels generate adhesives for staying in place when faced with waves and turbulence of the intertidal zone. Their byssal attachment assembly consists of adhesive plaques connected to the animal by threads. We have noticed that, every now and then, the animals tug on their plaque and threads. This observation had us wondering if the mussels temper or otherwise control catechol chemistry within the byssus in order to manage mechanical properties of the materials. Here, we carried out a study in which the adhesion properties of mussel plaques were compared when left attached to the animals versus detached and exposed only to an aquarium environment. For the most part, detachment from the animal had almost no influence on the mechanical properties on low-energy surfaces. There was a slight, yet significant difference observed with attached versus detached adhesive properties on high energy surfaces. There were significant differences in the area of adhesive deposited by the mussels on a low- versus a high-energy surface. Mussel adhesive plaques appear to be unlike, for example, spider silk, for which pulling on the material is needed for assembly of proteinaceous fibers to manage properties.