Vidres orgànics superestables

Els vidres estan presents en la nostra vida quotidiana, tant en aplicacions bàsiques com en sofisticades tecnologies. Però l'estudi dels vidres i el procés de vitrificació és encara de plena actualitat en el camp de la físico-química ja que presenta enigmes pendents de resolució. Investigadors del Grup de Nanomaterials i Microsistemes de la UAB han fet un nou pas per a respondre els interrogants que hi ha sobre la taula en descobrir algunes propietats dels vidres orgànics molt estables, materials de gran interès per les seves aplicacions tecnològiques.Los cristales están presentes en nuestra vida cotidiana, tanto en aplicaciones básicas como en sofisticadas tecnologías. Pero el estudio de los vidrios y el proceso de vitrificación es aún de plena actualidad en el campo de la físico-química ya que presenta enigmas pendientes de resolución. Investigadores del Grupo de Nanomateriales y Microsistemas de la UAB han dado un nuevo paso para responder a los interrogantes que hay sobre la mesa al descubrir algunas propiedades de los cristales orgánicos muy estables, materiales de gran interés por sus aplicaciones tecnológicas

Ultrafast Hole Spin Qubit with Gate-Tunable Spin-Orbit Switch

A key challenge in quantum computation is the implementation of fast and local qubit control while simultaneously maintaining coherence. Qubits based on hole spins offer, through their strong spin-orbit interaction, a way to implement fast quantum gates. Strikingly, for hole spins in one-dimensional germanium and silicon devices, the spin-orbit interaction has been predicted to be exceptionally strong yet highly tunable with gate voltages. Such electrical control would make it possible to switch on demand between qubit idling and manipulation modes. Here, we demonstrate ultrafast and universal quantum control of a hole spin qubit in a germanium/silicon core/shell nanowire, with Rabi frequencies of several hundreds of megahertz, corresponding to spin-flipping times as short as ~1 ns - a new record for a single-spin qubit. Next, we show a large degree of electrical control over the Rabi frequency, Zeeman energy, and coherence time - thus implementing a switch toggling from a rapid qubit manipulation mode to a more coherent idling mode. We identify an exceptionally strong but gate-tunable spin-orbit interaction as the underlying mechanism, with a short associated spin-orbit length that can be tuned over a large range down to 3 nm for holes of heavy-hole mass. Our work demonstrates a spin-orbit qubit switch and establishes hole spin qubits defined in one-dimensional germanium/silicon nanostructures as a fast and highly tunable platform for quantum computation

Lattice compression increases the activation barrier for phase segregation in mixed-halide perovskites

The bandgap tunability of mixed-halide perovskites makes them promising candidates for light emitting diodes and tandem solar cells. However, illuminating mixed-halide perovskites results in the formation of segregated phases enriched in a single-halide. This segregation occurs through ion migration, which is also observed in single-halide compositions, and whose control is thus essential to enhance the lifetime and stability. Using pressure-dependent transient absorption spectroscopy, we find that the formation rates of both iodide- and bromide-rich phases in MAPb(BrxI1-x)3 reduce by two orders of magnitude on increasing the pressure to 0.3 GPa. We explain this reduction from a compression-induced increase of the activation energy for halide migration, which is supported by first-principle calculations. A similar mechanism occurs when the unit cell volume is reduced by incorporating a smaller cation. These findings reveal that stability with respect to halide segregation can be achieved either physically through compressive stress or chemically through compositional engineering

Decoding reactive structures in dilute alloy catalysts

Rational catalyst design is crucial toward achieving more energy-efficient and sustainable catalytic processes. Understanding and modeling catalytic reaction pathways and kinetics require atomic level knowledge of the active sites. These structures often change dynamically during reactions and are difficult to decipher. A prototypical example is the hydrogen-deuterium exchange reaction catalyzed by dilute Pd-in-Au alloy nanoparticles. From a combination of catalytic activity measurements, machine learning-enabled spectroscopic analysis, and first-principles based kinetic modeling, we demonstrate that the active species are surface Pd ensembles containing only a few (from 1 to 3) Pd atoms. These species simultaneously explain the observed X-ray spectra and equate the experimental and theoretical values of the apparent activation energy. Remarkably, we find that the catalytic activity can be tuned on demand by controlling the size of the Pd ensembles through catalyst pretreatment. Our data-driven multimodal approach enables decoding of reactive structures in complex and dynamic alloy catalysts

Acknowledgment to Reviewers of Nanomaterials in 2021

Rigorous peer-reviews are the basis of high-quality academic publishing [...

Nanomaterials 2021 Best Paper Awards: Announcement and Interview with the Winner—Xin Huang

After an extensive voting period, we are proud to present the Best Paper Award to “Nanomaterials for the Removal of Heavy Metals from Wastewater [...

Acknowledgment to Reviewers of Nanomaterials in 2020

Peer review is the driving force of journal development, and reviewers are gatekeepers who ensure that Nanomaterials maintains its standards for the high quality of its published papers [...

Nanomaterials 2021 Best Paper Awards: Announcement and Interview with the Winner

After an extensive voting period, we are proud to present the Best Paper Award to “Carbon Dots and Graphene Quantum Dots in Electrochemical Biosensing [...

Acknowledgment to Reviewers of <i>Nanomaterials</i> in 2020

Peer review is the driving force of journal development, and reviewers are gatekeepers who ensure that Nanomaterials maintains its standards for the high quality of its published papers [...

Erratum: Mustafa, R.; Luo, Y.; Wu, Y.; Guo, R.; Shi, X. Dendrimer-Functionalized Laponite® Nanodisks as a Platform for Anticancer Drug Delivery. Nanomaterials 2015, 5, 1716–1731

It has been brought to our attention that Laponite® is a trademark of BYK Additives, however the trademark symbol is missing in [1].[...