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Ge alloying enables independent control of forward and reverse metal–insulator transitions in VO2, enabling decoupling of transformation-temperature and hysteresis.

As a result of the depletion of conventional oil reserves and the unprecedented growth in world energy demand, increasing attention has focused on the extraction and utilization of unconventional o...

It is urgently desired yet challenging to synthesize porous graphitic carbon (PGC) in a bottom-up manner while circumventing the need for high-temperature pyrolysis. Here we present an effective and scalable strategy to synthesize PGC through acid-mediated aldol triple condensation followed by low-temperature graphitization. The deliberate structural design enables its graphitization in situ in solution and at low pyrolysis temperature. The resulting material features ultramicroporosity characterized by a sharp pore size distribution. In addition, the pristine homogeneous composition of the reaction mixture allows for solution-processability of the material for further characterization and applications. Thin films of this PGC exhibit several orders of magnitude higher electrical conductivity compared to analogous control materials that are carbonized at the same temperatures. The integration of low-temperature graphitization and solution-processability not only allows for an energy-efficient method for the production and fabrication of PGC, but also paves the way for its wider employment in applications such as electrocatalysis, sensing, and energy storage., Porous graphitic carbon was synthesized through acid-mediated aldol triple condensation followed by low-temperature graphitization. The inherent thin film processability and the low temperature requirement of the synthesis enable various potential applications.

An energy storage paradigm orthogonal to Li-ion battery chemistries can be conceptualized by employing anions as the primary charge carriers. F-ion conversion chemistries show promise but have limi...

Summary Fluoride-ion batteries are an attractive energy storage concept analogous to lithium-ion batteries but feature an inverted paradigm where anions are the principal charge carriers. Insertion hosts that can reversibly insert fluoride ions at room temperature are exceedingly sparse. Here, we report that topochemical insertion of fluoride ions in FeSb2O4 involves Fe2+/Fe3+ redox but is mediated by multi-center synergies between iron and antimony centers. Separation of the redox center from the p-block coordination site alleviates structural strain by enabling compensatory contraction and expansion of FeO6 and SbO3 polyhedra, respectively. p-block electron lone pairs play a critical role in weakening anion-lattice interactions, enabling reversible fluoride-ion diffusion across microns. The results illuminate the key principle that interactions traceable to stereoactive lone pairs can be used to mediate anion-lattice interactions and suggest that anion insertion hosts can be designed by pairing redox-active transition metals with p-block cations bearing stereochemically active electron lone pairs.

A continuous increase in the global demand for liquid fuels has led to increased reliance on unconventional sources of fossil fuels such as bitumen. The extraction, midstream transportation, and ultimate processing of heavy oils presents a distinctive set of challenges. For example, the high viscosity of bitumen poses a challenge to its transportation through conventional transportation systems such as pipelines. Conventional approaches to address the challenging rheological properties of bitumen involve dilution of bitumen with natural gas condensates, addition of surfactants, ultrasonic heating, thermal jacketing of pipelines, and high pump pressures. These solutions require considerable investments in infrastructure, frequent inspection and maintenance, and pose a risk of spillage to vulnerable environments. As such, much interest has focused on the design of solid-state transportation methodologies. In this article, we propose a viable and safe transportation alternative wherein bitumen is reconfigured such that the droplets of lighter fractions of bitumen (saturates, aromatics, resins) are encapsulated within conformal shells of asphaltenes. The tendency of asphaltenes to aggregate has been exploited to obtain cross-linked shells without requiring the use of extraneous chemical additives. Thermally mediated crosslinking of the asphaltenes shells allow the microcapsules to hold their form and result in the emergence of mechanical strength. The stress-withstanding abilities and velocity impact resistance of these microcapsules have been studied to establish their viability for industrial use, and demonstrate that microcapsules with diameters of ca. 1.25 mm can withstand stresses as high as 576 kN/m2. Since the bitumen microcapsules have been formulated by simply reconfiguring the intrinsic components of bitumen, they can be readily fluidized by mechanical means to recover the encapsulated lighter fractions. The solid microcapsules demonstrate the viability of solid-state transportation of bitumen via roadways or marine tankers, thereby mitigating a primary impediment to the utilization of viscous oils.

Water, the driver of nature, has always been polluted by the blind hurling of highly toxic contaminants, but human-friendly science has continuously been presenting better avenues to help solve these challenging issues. In this connection, the present study introduces novel nanocomposites composed of emulsion-templated hierarchically porous poly(1-vinylimidazole) beads loaded with the silver nanoparticles generated via an in situ approach. These nanocomposites have been thoroughly characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, Brunauer-Emmett-Teller, and field emission scanning electron microscopy. The appropriate surface chemistry, good thermal stability, swelling behavior, porosity, and nanodimensions contributed to achieve very good performance in water treatment. Owing to their easier handling and separation, these novel nanocomposites are highly efficient to remove arsenic and eriochrome black T with decent adsorption capacities in addition to the inactivation and killing of Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) bacteria.

The design of earth-abundant electrocatalysts that can facilitate water splitting at low overpotentials, provide high current densities, and enable prolonged operational lifetimes is central to the production of sustainable fuels. The distinctive atomistic and electronic structure characteristics of the edges of MoS2 imbue high reactivity toward the hydrogen evolution reaction. MoS2 is nevertheless characterized by significantly high overpotentials as compared to platinum. Here, we demonstrate that modulation of the electronic structure of MoS2 through interfacial hybridization with MoO3 and alloying of selenium on the anion sublattice allows for systematic lowering of the conduction band edge and raising of the valence band edge, respectively. The former promotes enhanced electrocatalytic activity toward hydrogen evolution, whereas the latter promotes enhanced activity toward the oxygen evolution reaction. Such alloyed heterostructures prepared by sol-gel reactions and hydrothermal selenization expose a high density of edge sites. The alloyed heterostructures exhibit low overpotential, high current density, high turnover frequency, and prolonged operational lifetime. The mechanistic origins of catalytic activity have been established based on electronic structure calculations and x-ray absorption and emission spectroscopy probes of electronic structure, which suggest that interfacial hybridization at the MoO3 interface yields low-lying conduction band states that facilitate hydrogen adsorption. In contrast, shallow Se 4p-derived states give rise to a raised effective valence band maximum, which facilitates adsorption of oxygen intermediates and engenders a low overpotential for the oxygen evolution reaction. The findings illustrate the use of electronic structure modulation through interfacial hybridization and alloying to systematically improve electrocatalytic activity.