Many applications proposed for graphene require multiple sheets be assembled into a monolithic structure. The ability to maintain structural integrity upon large deformation is essential to ensure a ...macroscopic material which functions reliably. However, it has remained a great challenge to achieve high elasticity in three-dimensional graphene networks. Here we report that the marriage of graphene chemistry with ice physics can lead to the formation of ultralight and superelastic graphene-based cellular monoliths. Mimicking the hierarchical structure of natural cork, the resulting materials can sustain their structural integrity under a load of >50,000 times their own weight and can rapidly recover from >80% compression. The unique biomimetic hierarchical structure also provides this new class of elastomers with exceptionally high energy absorption capability and good electrical conductivity. The successful synthesis of such fascinating materials paves the way to explore the application of graphene in a self-supporting, structurally adaptive and 3D macroscopic form.
A new member of the layered pseudo‐1D material family—monoclinic gallium telluride (GaTe)—is synthesized by physical vapor transport on a variety of substrates. The 010 atomic chains and the ...resulting anisotropic behavior are clearly revealed. The GaTe flakes display multiple sharp photoluminescence emissions in the forbidden gap, which are related to defects localized around selected edges and grain boundaries.
Achieving stability with highly active Ru nanoparticles for electrocatalysis is a major challenge for the oxygen evolution reaction. As improved stability of Ru catalysts has been shown for bulk ...surfaces with low‐index facets, there is an opportunity to incorporate these stable facets into Ru nanoparticles. Now, a new solution synthesis is presented in which hexagonal close‐packed structured Ru is grown on Au to form nanoparticles with 3D branches. Exposing low‐index facets on these 3D branches creates stable reaction kinetics to achieve high activity and the highest stability observed for Ru nanoparticle oxygen evolution reaction catalysts. These design principles provide a synthetic strategy to achieve stable and active electrocatalysts.
Au‐Ru nanoparticles with 3D and faceted branches are synthesized using a new approach for bimetallic systems. The well‐defined structure enables record high stability for Ru electrocatalysts to be achieved while retaining high activity in the oxygen evolution reaction.
Abstract
The soil carbon (C) saturation concept suggests an upper limit to the storage of soil organic carbon (SOC). It is set by the mechanisms that protect soil organic matter from mineralization. ...Biochar has the capacity to protect new C, including rhizodeposits and microbial necromass. However, the decadal-scale mechanisms by which biochar influences the molecular diversity, spatial heterogeneity, and temporal changes in SOC persistence, remain unresolved. Here we show that the soil C storage ceiling of a Ferralsol under subtropical pasture was raised by a second application of
Eucalyptus saligna
biochar 8.2 years after the first application—the first application raised the soil C storage ceiling by 9.3 Mg new C ha
−1
and the second application raised this by another 2.3 Mg new C ha
−1
. Linking direct visual evidence from one-, two-, and three-dimensional analyses with SOC quantification, we found high spatial heterogeneity of C functional groups that resulted in the retention of rhizodeposits and microbial necromass in microaggregates (53–250 µm) and the mineral fraction (<53 µm). Microbial C-use efficiency was concomitantly increased by lowering specific enzyme activities, contributing to the decreased mineralization of native SOC by 18%. We suggest that the SOC ceiling can be lifted using biochar in (sub)tropical grasslands globally.
Detonation nanodiamonds have found numerous potential applications in a diverse array of fields such as biomedical imaging and drug delivery. Here, we systematically characterized non-functionalized ...and polyglycerol-functionalized detonation nanodiamond particles (DNPs) dispersed in aqueous suspensions at different ionic strengths (∼1.0 × 10
to 1.0 × 10
M) via dynamic light scattering and cryogenic transmission electron microscopy. For these colloidal suspensions, the total potential energies of interactions between a pair of DNPs were theoretically calculated using the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory plus the fitting of the Boltzmann distribution to the interparticle spacing distribution of the colloidal DNPs. These investigations revealed that the non-functionalized DNPs are dispersed in aqueous media through the long-range (>10 nm) and weak (<7
) electrical double-layer repulsive interaction, while the driving force on dispersion of polyglycerol-functionalized DNPs is mostly derived from the short-range (<2 nm) and strong (∼55
) steric repulsive potential barrier generated by the polyglycerol. Moreover, our results show that the truly monodispersed and individually dispersed DNP colloids, forming no aggregates in aqueous suspensions, are available by both functionalizing DNPs by polyglycerol and increasing ionic strength of suspending media to ≳1.0 × 10
M.
Single‐atom catalysts (SACs) exhibit unparalleled atomic utilization and catalytic efficiency, yet it is challenging to modulate SACs with highly dispersed single‐atoms, mesopores, and well‐regulated ...coordination environment simultaneously and ultimately maximize their catalytic efficiency. Here, a generalized strategy to construct highly active ferric‐centered SACs (Fe‐SACs) is developed successfully via a biomineralization strategy that enables the homogeneous encapsulation of metalloproteins within metal–organic frameworks (MOFs) followed by pyrolysis. The results demonstrate that the constructed metalloprotein‐MOF‐templated Fe‐SACs achieve up to 23‐fold and 47‐fold higher activity compared to those using metal ions as the single‐atom source and those with large mesopores induced by Zn evaporation, respectively, as well as up to a 25‐fold and 1900‐fold higher catalytic efficiency compared to natural enzymes and natural‐enzyme‐immobilized MOFs. Furthermore, this strategy can be generalized to a variety of metal‐containing metalloproteins and enzymes. The enhanced catalytic activity of Fe‐SACs benefits from the highly dispersed atoms, mesopores, as well as the regulated coordination environment of single‐atom active sites induced by metalloproteins. Furthermore, the developed Fe‐SACs act as an excellent and effective therapeutic platform for suppressing tumor cell growth. This work advances the development of highly efficient SACs using metalloproteins‐MOFs as a template with diverse biotechnological applications.
A generalized strategy to construct highly active ferric‐centered SACs (Fe‐SACs) via a biomineralization strategy that enables the homogeneous encapsulation of metalloproteins within metal–organic frameworks (MOFs) followed by pyrolysis is developed. The enhanced catalytic activity of the Fe‐SACs benefits from the highly dispersed atoms, mesopores, as well as the regulated coordination environment of single‐atom active sites induced by metalloproteins.
Insects of the order Embioptera, known as embiopterans, embiids, or webspinners, weave silk fibers together into sheets to make shelters called galleries. In this study, we show that silk galleries ...produced by the embiopteran Antipaluria urichi exhibit a highly hydrophobic wetting state with high water adhesion macroscopically equivalent to the rose petal effect. Specifically, the silk sheets have advancing contact angles above 150°, but receding contact angle approaching 0°. The silk sheets consist of layered fiber bundles with single strands spaced by microscale gaps. Scanning and transmission electron microscopy (SEM, TEM) images of silk treated with organic solvent and gas chromatography mass spectrometry (GC-MS) of the organic extract support the presence of a lipid outer layer on the silk fibers. We use cryogenic SEM to demonstrate that water drops reside on only the first layer of the silk fibers. The area fraction of this sparse outer silk layers is 0.1 to 0.3, which according to the Cassie-Baxter equation yields an effective static contact angle of ∼130° even for a mildly hydrophobic lipid coating. Using high magnification optical imaging of the three phase contact line of a water droplet receding from the silk sheet, we show that the high adhesion of the drop stems from water pinning along bundles of multiple silk fibers. The bundles likely form when the drop contact line is pinned on individual fibers and pulls them together as it recedes. The dynamic reorganization of the silk sheets during the droplet movement leads to formation of "super-pinning sites" that give embiopteran silk one of the strongest adhesions to water of any natural hydrophobic surface.
Carbon-supported cobalt–iron(II,III) oxide (Co–Fe3O4) hybrid nanoparticles (Co–Fe3O4/C) are prepared as efficient catalysis of the oxygen reduction reaction (ORR) in alkaline media and in the cathode ...of the anion exchange membrane fuel cell (AEMFC). The ORR activity of Co–Fe3O4/C gives an electron transfer number of 3.99, revealing almost perfect four-electron transfer, over a very wide range of potentials of 0.1–0.8 V. Co–Fe3O4/C is more durable than Pt/C in alkaline media, undergoing almost no degradation in 10,000 s at 0.76 V (vs. RHE). The potential-cycling method shows that the rate of decline of Co–Fe3O4/C is only 5% decay after 10,000 cycles. The AEMFC using Co–Fe3O4/C also shows good performance and excellent durability in this study.
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•The ORR activity of Co–Fe3O4 catalysis is 3.99 of electron-transfer number.•The enhanced ORR activity of catalysis is due to its high redox potential.•The AEMFC using Co–Fe3O4 catalysis shows a high performance with an OCP of 0.85 V.
Hybrid halide perovskites have emerged as highly promising photovoltaic materials because of their exceptional optoelectronic properties, which are often optimized via compositional engineering like ...mixing halides. It is well established that hybrid perovskites undergo a series of structural phase transitions as temperature varies. In this work, the authors find that phase transitions are substantially suppressed in mixed‐halide hybrid perovskite single crystals of MAPbI3‐xBrx (MA = CH3NH3+ and x = 1 or 2) using a complementary suite of diffraction and spectroscopic techniques. Furthermore, as a general behavior, multiple crystallographic phases coexist in mixed‐halide perovskites over a wide temperature range, and a slightly distorted monoclinic phase, hitherto unreported for hybrid perovskites, is dominant at temperatures above 100 K. The anomalous structural evolution is correlated with the glassy behavior of organic cations and optical phonons in mixed‐halide perovskites. This work demonstrates the complex interplay between composition engineering and lattice dynamics in hybrid perovskites, shedding new light on their unique properties.
Structural phase transitions are found to be substantially suppressed in mixed‐halide hybrid perovskites of MAPbI2Br and MAPbIBr2 (MA = CH3NH3+), because of the glassy behavior of organic cations and optical phonons. A slightly distorted monoclinic phase is dominant and coexists with multiple crystallographic phases over a wide temperature range.
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