Highlights

Researchers at NCCR MARVEL have combined first principles calculations with soft X-ray angle-resolved photoemission spectroscopy to examine tungsten diphosphide’s electronic structure, characterizing its Weyl nodes for the very first time. In agreement with density functional theory calculations, the results revealed two pairs of Weyl nodes lying at different binding energies. The observation of the Weyl nodes, as well as the tilted cone-like dispersions in the vicinity of the nodal points, provides compelling evidence that the material is a robust type-II Weyl semimetal with broken Lorentz invariance. This is as MARVEL researchers predicted two years ago. The research has been published in Physical Review Letters as an Editor's Suggestion.

Researchers working within NCCR MARVEL have discovered a self-healing catalyst that can be used to release hydrogen through the hydrolytic dehydrogenation of ammonia borane. The catalyst, SION-X, is based on the abundant mineral Jacquesdietrichite, is sustainable, air stable and can be easily regenerated, stored and handled. These characteristics mean that it may offer significant advantages over existing catalysts used in the production of the clean and renewable energy carrier hydrogen. The research has been published in the Journal of Materials Chemistry A. 

EPFL chemical engineers led by Kyriakos Stylianou, experimental group leader in MARVEL Design and Discovery Project 4, have synthesized a biologically-derived metal-organic framework on which the hydrogen bonding that forms the DNA double helix can be mimicked and studied like never before. The paper, Nucleobase pairing and photodimerization in a biologically derived metal-organic framework nanoreactor, has been published in Nature Communications.

Scientists have known about the existence of the hydrated electron -- extra electrons solvated in liquid water -- for more than fifty years. They haven't been too sure of its structure though. MARVEL researchers at the University of Zurich, ETH and the Swiss National Supercomputing Center CSCS have now taken a huge step towards solving the mystery. Their paper, 'Dynamics of the Bulk Hydrated Electron from Many Body Wave Function Theory," has been published in Angewandte Chemie.

A study into the effects of high mechanical pressure on the polyiodide TEAI showed that it brings unusually high electrical conductivity starting from insulating state, suggesting that the material may be useful as a switchable semiconductor. This system could represent an alternative to gel electrolytes and ionic liquids in dye-synthesized solar cells. The paper, Pressure-induced Polymerization and Electrical Conductivity of a Polyiodide, has been published as a Very Important Paper in Angewandte Chemie.

Understanding how defects can affect ground-state properties, promote phase transitions, or enable entirely new functionalities in some strongly correlated oxides has become a subject of major interest in the field of design and discovery of novel functional materials. SrMnO3 (SMO) is a particularly interesting example, but better characterization is needed. MARVEL researchers have now a developed a method that may lead to more accurate predictions of the energetics of defects associated with in-gap states in semiconductors or insulators.

EPFL chemists have developed a new iron-nickel oxide catalyst for water splitting, the reaction that produces hydrogen fuel. The patent-pending catalyst shows significantly higher activity in the oxygen-evolution part of reaction than conventional nickel iron oxide catalysts. The work, now published in ACS Central Science, was supported by the density functional theory (DFT) computations of NCCR MARVEL's Clémence Corminboeuf and her postdoctoral student Michael Busch: their work underpinned the possible theoretical explanations.

Transforming emitted CO2 into valuable products has been proposed as a way of reducing the amount of this greenhouse gas released into the atmosphere—using it as a raw material could help both close the carbon cycle and reduce the consumption of petrochemicals. Dr. Kyriakos C. Stylianou of EPFL and NCCR MARVEL and EPFL's Professor Paul Dyson have developed a recyclable catalyst that can be used to produce valuable products. The research has been published in Angewandte Chemie.

NCCR MARVEL’s Michele Ceriotti and Clemence Corminboeuf have joined forces to develop an innovative machine learning model for the electron density. Knowledge of a system’s electron density gives access in principle to all its ground state properties. However, the computations needed to determine the electronic structure from first principles remain costly. A machine learning approach promises to lighten this computational burden significantly.

Topological materials – unusual materials whose surface properties are different from those in the bulk – have generated significant interest in recent years because of their unique characteristics. Topological insulators, for instance, are electrical insulators in the bulk, but conduct electricity on their surfaces or edges.

Researcher Kyriakos Stylianou from the lab of NCCR MARVEL's deputy director Berend Smit and colleagues have developed a portable and user-friendly device that can measure fluoride concentration accurately and reliably.

Researchers from the lab of NCCR MARVEL's deputy director Berend Smit and colleagues have developed a methodology for collecting the lessons learned from partially failed trials and incorrect hypotheses -- the experiments that didn't work. The research was published in Nature Communications.