2020 New's Items

Architectural Stabilization of a Gold(III) Catalyst in Metal-Organic Frameworks

Lee JS
Kapustin EA
Pei X
Llopis S
Yaghi OM
Toste FD
2020

Unimolecular decomposition pathways are challenging to address in transition-metal catalysis and have previously not been suppressed via incorporation into a solid support. Two robust metal-organic frameworks (IRMOF-10 and bio-MOF-100) are used for the architectural stabilization of a structurally well-defined gold(III) catalyst. The inherent rigidity of these materials is utilized to preclude a unimolecular decomposition pathway—reductive elimination. Through this architectural stabilization strategy, decomposition of the incorporated gold(III) catalyst in the metal-organic...

Shape-controlled single-crystal growth of InP at low temperatures down to 220 °C

Hettick M
Li H
Lien DH
Yeh M
Yang TY
Amani M
Gupta N
Chrzan DC
Chueh YL
Javey A
2020

III–V compound semiconductors are widely used for electronic and optoelectronic applications. However, interfacing III–Vs with other materials has been fundamentally limited by the high growth temperatures and lattice-match requirements of traditional deposition processes. Recently, we developed the templated liquid-phase (TLP) crystal growth method for enabling direct growth of shape-controlled single-crystal III-Vs on amorphous substrates. Although in theory, the lowest temperature for TLP growth is that of the melting point of the group III metal (e.g., 156.6 °C for indium),...

A Porous Covalent Organic Framework with Voided Square Grid Topology for Atmospheric Water Harvesting

Nguyen HL
Hanikel N
Lyle SJ
Zhu C
Proserpio DM
Yaghi OM
2020

Atmospheric moisture is a ubiquitous water resource available at any time and any place, making it attractive to develop materials for harvesting water from air to address the imminent water shortage crisis. In this context, we have been exploring the applicability of covalent organic frameworks (COFs) for water harvesting and report here a new porous, two-dimensional imine-linked COF with a voided square grid topology, termed COF-432. Unlike other reported COFs, COF-432 meets the requirements desired for water harvesting from air in that it exhibits an S-shaped water sorption...

Uncharted Waters: Super-Concentrated Electrolytes

Borodin O
Self J
Persson KA
Wang C
Xu K
2020

The traditional efforts in electrolytes have been mostly evolving around the “1 M” region, where maximum ion conductivities occur in the majority of non-aqueous electrolyte systems. However, recent deviation from this “optimum” concentration has revealed to us that there is a new world. In the super-concentrated regions, the reversed salt/solvent ratio brought dramatic changes in bulk liquid structures, ion transport, and interfacial and interphasial properties. Some of these unusual properties have been found to introduce benefits to electrochemical, thermal, transport, interfacial...

Difference frequency generation in topological semimetals

De Juan F
Zhang Y
Morimoto T
Sun Y
Moore JE
Grushin AG
2020

When two lasers are applied to a noncentrosymmetric material, it can generate light at the difference of the incoming frequencies Δω, a phenomenon known as difference frequency generation (DFG), well characterized in semiconductors. In this work, we derive a general expression for DFG in metals, which we use to show that the DFG in chiral topological semimetals under circular polarized light is quantized in units of ...

The lithiation process and Li diffusion in amorphous SiO2 and Si from first-principles

Sivonxay E
Aykol M
Persson KA
2020

Silicon is considered the next-generation, high-capacity anode for Li-ion energy storage applications, however, despite significant effort, there are still uncertainties regarding the bulk Si and surface SiO2 structural and chemical evolution as it undergoes lithiation and ...

Reversible writing of high-mobility and high-carrier-density doping patterns in two-dimensional van der Waals heterostructures

Shi W
Kahn S
Jiang L
Wang SY
Tsai HZ
Wong D
Taniguchi T
Watanabe K
Wang F
Crommie MF
Zettl A
2020

A key feature of two-dimensional materials is that the sign and concentration of their carriers can be externally controlled with techniques such as electrostatic gating. However, conventional electrostatic gating has limitations, including a maximum carrier density set by the dielectric breakdown, and ionic liquid gating and direct chemical doping also suffer from drawbacks. Here, we show that an electron-beam-induced doping technique can be used to reversibly write high-resolution doping patterns in hexagonal boron nitride-encapsulated graphene and molybdenum disulfide (MoS...

Scalable Electrically Conductive Spray Coating Based on Block Copolymer Nanocomposites

Kwon J
Evans K
Ma L
Arnold D
Yildizdag ME
Zohdi T
Ritchie RO
Xu T
2020

Currently available conductive inks present a challenge to achieving electrical performance without compromising mechanical properties, scalability, and processability. Here, we have developed blends of carbon black and the commercially available triblock copolymer (BCP), poly(styrene-ethylene-butylene-styrene)-g-maleic anhydride (SEBS-g-MAH) (FG1924G, Kraton), that can be readily applied as a conductive coating via a spray-coating process, for a wide range of insulating materials (fabric, wood, glass, and plastic). Simple but effective mechanical and...

Charge fluctuations from molecular simulations in the constant-potential ensemble

Scalfi L
Limmer DT
Coretti A
Monella S
Madden PA
Salanne M
Rotenberg B
2020

We revisit the statistical mechanics of charge fluctuations in capacitors. In constant-potential classical molecular simulations, the atomic charges of electrode atoms are treated as additional degrees of freedom which evolve in time so as to satisfy the constraint of fixed electrostatic potential for each configuration of the electrolyte. The present work clarifies the role of the overall electroneutrality constraint, as well as the link between the averages computed within the Born–Oppenheimer approximation and that of the full constant-potential ensemble. This allows us in...

Surface and Interface Control in Nanoparticle Catalysis

Xie C
Niu Z
Kim D
Li M
Yang P
2020

The surface and interfaces of heterogeneous catalysts are essential to their performance as they are often considered to be active sites for catalytic reactions. With the development of nanoscience, the ability to tune surface and interface of nanostructures has provided a versatile tool for the development and optimization of a heterogeneous catalyst. In this Review, we present the surface and interface control of nanoparticle catalysts in the context of oxygen reduction reaction (ORR), electrochemical CO2 reduction reaction (CO2...