hard X-ray photoelectron spectroscopy

BESSY II: How intrinsic oxygen shortens the lifespan of solid-state batteries

2026/05/082026/05/28

Although solid-state batteries (SSBs) demonstrate high performance and are intrinsically safe, their capacity currently declines rapidly. A team from the TU Wien, Humboldt-University Berlin and HZB has now analysed a TiS₂|Li₃YCl₆ solid-state half-cell in operando at BESSY II using a special sample environment that allows for non-destructive investigation under real operating conditions. Data obtained by combination of soft and hard X-ray photoelectron spectroscopy (XPS and HAXPES) revealed a new degradation mechanism that had not previously been identified in solid-state batteries. They have gained some surprising insights, particularly regarding the harmful role played by intrinsic oxygen. This study provides valuable information for improving design and handling of such batteries.

Solid-state batteries (SSBs) offer several advantages over conventional batteries, including higher energy and power densities, as well as greater safety, as they do not contain flammable liquid electrolytes. However, since lithium ions migrate between the working electrode and the counter-electrode during operation, the solid material can suffer by volume changes, which can lead to cracks. In order to maintain contact between electrodes and electrolyte, SSBs must be operated under high pressure. Volume changes, as well as degradation processes at the interfaces, often limit the lifespan of these batteries. Until now, it has been virtually impossible to observe these processes experimentally, particularly due to the high stacking pressure required during operation. However, Dr Elmar Kataev, a scientist at HZB, has now developed a sample environment that enables operando analysis of SSBs under high pressure using two-colour – soft and hard – X-ray photoelectron spectroscopy (XPS and HAXPES) at the SISSY endstation at BESSY II. These conditions of combining two different energies of X-rays (hard for bulk sensitivity and soft – for surface) hitting the same spot is exclusively available at EMIL beamline.

Read more on the HZB website

Image: A view of the operando cell in the sample chamber during the measurements at the SISSY Endstation.

Credit: © E. Kataev/HZB

Engineered wall paint could kill corona viruses

2023/03/082023/03/17

Investigation of aerosols on titanium dioxide shows promising routes to surface and air disinfection

Common wall paint could potentially be modified to kill the Corona virus and many other pathogens. This is an important finding of a study from a research team including DESY scientists on the virus-killing effect of titanium dioxide (TiO₂), a ubiquitous white pigment that is found in paints, plastic products and sunscreens. TiO₂ also has many other important applications relevant to environmental sustainability and renewable energy. The international team led by Heshmat Noei from the DESY NanoLab reports its results in the journal Applied Materials & Interfaces published by the American Chemical Society (ACS).

“Titanium dioxide is widely used as a pigment to whiten a wide range of products,” explains Noei. “But it is also a powerful catalyst in many applications such as air and water purification and self-cleaning materials. Therefore, we saw it as a promising candidate for a virus inactivating coating.” Teaming up with the group of virologist Ulrike Protzer and Greg Ebert from the research centre Helmholtz Munich and the Technische Universität München, the scientists tested titanium dioxide´s power against the corona virus. “We were the first to apply corona viruses on a titanium dioxide surface and investigate what happens,” says Noei.

Hard X-ray photoelectron spectroscopy at the PETRA III beamline P22 at DESY provides the necessary high chemical and elemental sensitivity to resolve subtle chemical changes. The research team investigated the contact process on the surface and was able to clarify that the amino acids of the corona virus spike protein attach to the titanium dioxide surface, trapping the virus and preventing it from binding to human cells. “We found that the virus adsorbs to the titanium dioxide surface and cannot detach again and will eventually be inactivated by dehydration and be denatured,” explains the paper´s main author Mona Kohantorabi from the DESY NanoLab. “Moreover, the titanium dioxide catalyses the inactivation of the virus by light. For our study we used ultraviolet light, which triggered the inactivation of the virus within 30 minutes, but we believe the catalyst can be further optimised to accelerate the inactivation and, more importantly, work under standard indoor lighting. We believe it could then be used as an antiviral coating for walls, windows and other surfaces for instance in hospitals, schools, airports, elderly homes and kindergardens.”

Read more on the DESY website

Image: An image taken with an atomic force microscope from the investigation: The SARS-CoV-2 particles (light) adsorb on the titanium dioxide surface. There, structural proteins are inactivated by denaturation and oxidation by light irradiation.

Credit: DESY Nanolab, Mona Kohantorabi

Solar hydrogen: Photoanodes made of α-SnWO4 promise high efficiencies

2021/01/262021/01/28

Photoanodes made of metal oxides are considered to be a viable solution for the production of hydrogen with sunlight. α-SnWO₄ has optimal electronic properties for photoelectrochemical water splitting with sunlight, but corrodes easily. Protective layers of nickel oxide prevent corrosion, but reduce the photovoltage and limit the efficiency. Now a team at HZB has investigated at BESSY II what happens at the interface between the photoanode and the protective layer. Combined with theoretical methods, the measurement data reveal the presence of an oxide layer that impairs the efficiency of the photoanode.

Hydrogen is an important factor in a sustainable energy system. The gas stores energy in chemical form and can be used in many ways: as a fuel, a feedstock for other fuels and chemicals or even to generate electricity in fuel cells. One solution to produce hydrogen in a climate-neutral way is the electrochemical splitting of water with the help of sunlight. This requires photoelectrodes that provide a photovoltage and photocurrent when exposed to light and at the same time do not corrode in water. Metal oxide compounds have promising prerequisites for this. For example, solar water splitting devices using bismuth vanadate (BiVO₄) photoelectrodes achieve already today ~8 % solar-to-hydrogen efficiency, which is close to the material’s theoretical maximum of 9 %.