2021 New's Items

Photoinduced Charge Transfer and Trapping on Single Gold Metal Nanoparticles on TiO2

Luna M
Barawi M
Gómez-Moñivas S
Colchero J
Rodríguez-Peña M
Yang S
Zhao X
Lu Y-H
Chintala R
Reñones P
Altoe V
Martínez L
Huttel Y
Kawasaki S
Weber-Bargioni A
de la Peña ÓShea VA
Yang P
Ashby PD
Salmeron M
2021

We present a study of the effect of gold nanoparticles (Au NPs) on TiO2 on charge generation and trapping during illumination with photons of energy larger than the substrate band gap. We used a novel characterization technique, photoassisted Kelvin probe force microscopy, to study the process at the single Au NP level. We found that the photoinduced electron transfer from TiO2 to the Au NP increases logarithmically with light intensity due to the combined contribution of electron–hole pair generation in the space charge region in...

Interface Sensitivity in Electron/Ion Yield X-ray Absorption Spectroscopy: The TiO2–H2O Interface

Van Spronsen MA
Zhao X
Jaugstetter M
Escudero C
Duchoň T
Hunt A
Waluyo I
Yang P
Tschulik K
Salmeron MB
2021

To understand corrosion, energy storage, (electro)catalysis, etc., obtaining chemical information on the solid–liquid interface is crucial but remains extremely challenging. Here, X-ray absorption spectroscopy (XAS) is used to study the solid–liquid interface between TiO2 and H2O. A thin film (6.7 nm) of TiO2 is deposited on an X-ray-transparent SiNx window, acting as the working electrode in a three-electrode flow cell. The spectra are collected based on the electron emission...

Ligand-Free Processable Perovskite Semiconductor Ink

Folgueras MC
Louisia S
Jin J
Gao M
Du A
Fakra SC
Zhang R
Seeler F
Schierle-Arndt K
Yang P
2021

Traditional covalent semiconductors require complex processing methods for device fabrication due to their high cohesive energies. Here, we develop a stable, ligand-free perovskite semiconductor ink that can be used to make patterned semiconductor-based optoelectronics in one step. The perovskite ink is formed via the dissolution of crystals of vacancy-ordered double perovskite Cs2TeX6 (X = Cl–, Br–, I–) in polar aprotic solvents, leading to the...

Bottom-Up Synthesized Nanoporous Graphene Transistors

Mutlu Z
Jacobse PH
McCurdy RD
Llinas JP
Lin Y
Veber GC
Fischer FR
Crommie MF
2021

Nanoporous graphene (NPG) can exhibit a uniform electronic band gap and rationally-engineered emergent electronic properties, promising for electronic devices such as field-effect transistors (FETs), when synthesized with atomic precision. Bottom-up, on-surface synthetic approaches developed for graphene nanoribbons (GNRs) now provide the necessary atomic precision in NPG formation to access these desirable properties. However, the potential of bottom-up synthesized NPG for electronic devices has remained largely unexplored to date. Here, FETs based on bottom-up synthesized chevron-...

Evidence for quantum spin liquid behaviour in single-layer 1T-TaSe2 from scanning tunnelling microscopy

Ruan W
Chen Y
Tang S
Hwang J
Tsai HZ
Lee RL
Wu M
Ryu H
Kahn S
Liou F
Jia C
Aikawa AS
Hwang C
Wang F
Choi Y
Louie SG
Lee PA
Shen ZX
Mo SK
Crommie MF
2021

Two-dimensional triangular-lattice antiferromagnets are predicted under some conditions to exhibit a quantum spin liquid ground state with no energy barrier to create emergent, fractionalized spinon excitations that carry spin but no charge. Materials that realize this kind of spin liquid are expected to have a low-energy behaviour described by a spinon Fermi surface. Directly imaging the resulting spinons, however, is difficult due to their chargeless nature. Here we use scanning tunnelling spectroscopy to image density waves consistent with the predictions of spinon density...

Local Electronic Properties of Coherent Single-Layer WS2/WSe2 Lateral Heterostructures

Herbig C
Zhang C
Mujid F
Xie S
Pedramrazi Z
Park J
Crommie MF
2021

Lateral single-layer transition metal dichalcogenide (TMD) heterostructures are promising building blocks for future ultrathin devices. Recent advances in the growth of coherent heterostructures have improved the structural precision of lateral heterojunctions, but an understanding of the electronic effects of the chemical transition at the interface and associated strain is lacking. Here we present a scanning tunneling microscopy study of single-layer coherent TMD heterostructures with nearly uniform strain on each side of the heterojunction interface. We have characterized the...

Synergetic Bottom-Up Synthesis of Graphene Nanoribbons by Matrix-Assisted Direct Transfer

McCurdy RD
Jacobse PH
Piskun I
Veber GC
Rizzo DJ
Zuzak R
Mutlu Z
Bokor J
Crommie MF
Fischer FR
2021

The scope of graphene nanoribbon (GNR) structures accessible through bottom-up approaches is defined by the intrinsic limitations of either all-on-surface or all-solution-based synthesis. Here, we report a hybrid bottom-up synthesis of GNRs based on a Matrix-Assisted Direct (MAD) transfer technique that successfully leverages technical advantages inherent to both solution-based and on-surface synthesis while sidestepping their drawbacks. Critical structural parameters tightly controlled in solution-based polymerization reactions can seamlessly be translated into the structure of the...

Transfer-Free Synthesis of Atomically Precise Graphene Nanoribbons on Insulating Substrates

Mutlu Z
Llinas JP
Jacobse PH
Piskun I
Blackwell R
Crommie MF
Fischer FR
Bokor J
2021

The rational bottom-up synthesis of graphene nanoribbons (GNRs) provides atomically precise control of widths and edges that give rise to a wide range of electronic properties promising for electronic devices such as field-effect transistors (FETs). Since the bottom-up synthesis commonly takes place on catalytic metallic surfaces, the integration of GNRs into such devices requires their transfer onto insulating substrates, which remains one of the bottlenecks in the development of GNR-based electronics. Herein, we report on a method for the transfer-free placement of GNRs on...

Designing sub-20 nm self-assembled nanocarriers for small molecule delivery: Interplay among structural geometry, assembly energetics, and cargo release kinetics

Jung BT
Lim M
Jung K
Li M
Dong H
Dube N
Xu T
2021

Biological constraints in diseased tissues have motivated the need for small nanocarriers (10–30 nm) to achieve sufficient vascular extravasation and pervasive tumor penetration. This particle size limit is only an order of magnitude larger than small molecules, such that cargo loading is better described by co-assembly processes rather than simple encapsulation. Understanding the structural, kinetic, and energetic contributions of carrier-cargo co-assembly is thus critical to achieve molecular-level control towards predictable in vivo behavior. These...

Nanocomposites Based on Coil-Comb Diblock Copolymers

Huang J
Hall A
Jayapurna I
Algharbi S
Ginzburg V
Xu T
2021

The polymer chain architecture is an important factor determining the phase behavior of nanoparticle (NP) assembly in polymer matrices. Block copolymers (BCPs) containing a random copolymer (RCP) block present a convenient variation on traditional BCPs to tune the interaction parameters between the polymer blocks and the nanofillers as well as to evaluate the effect of the chain architecture on the NP arrangements within BCP microdomains. Here, we synthesized BCPs with a coil polystyrene (PS) block and a comb RCP block through reversible addition-fragmentation chain transfer...