Scientific Highlights

Decarbonization of the energy system across different sectors using power-to-X concepts relies heavily on the availability of low-cost hydrogen produced from renewable power by water electrolysis. Polymer electrolyte water electrolysis (PEWE) is a promising technology for hydrogen (and oxygen) production for distributed as a well as centralized operation. The total cost of hydrogen is dominated by the electricity cost. Therefore, increase of conversion efficiency is pivotal in improving the commercial viability of electrolytically produced hydrogen. In this study, we investigate the prospects of improving conversion efficiency by reducing the membrane thickness from 200 to 50 micron and increasing the cell temperature from 60 to 120°C.

Results are reported on B_S⁰ →μ⁺μ^- decays using 61 fb^-1 of proton-proton collision data obtained in 2011-2016 with the CMS experiment at the LHC (CERN). In the standard model (SM) of particle physics this decay can be precisely calculated with small theoretical uncertainties, making it an excellent probe for testing the limits of the SM. The branching fraction BF(B_S⁰ →μ⁺μ^-)=(2.9 ± 0.7) x 10^-9 is measured with a statistical significance of 5.6 standard deviations. In addition, the effective lifetime of this decay is measured as 𝜏_𝜇𝜇=1.70+0.61−0.44

ps. Both results are in good agreement with the SM prediction. In comparison to the previous analysis, a much improved muon identification algorithm significantly increased the purity and strongly reduced the background. As a consequence, the measurement of BF(B⁰ →μ⁺μ^-) < 3.6 x 10^-10 at 95% CL is no longer in tension to the SM, but fully compatible with it.

Silicon is a long-standing candidate for replacing graphite as the active material in negative electrodes for Li-ion batteries, due to its significantly higher specific capacity. However, Si suffers from rapid capacity loss, as a result of the large volume expansion and contraction during lithation and de-lithiation. As an alternative to pure Si electrodes, Si could be used as a capacity-enhancing additive to graphite electrodes.

In December 2020, the Swiss Academy of Sciences (SCNAT) published its white book on radiochemical education in Switzerland. The report was authored under the lead of Prof. Dr. Roger Alberto (University of Zurich), Dr. Mario Burgener (Spiez Laboratory), and Prof. em. Dr. Heinz W. Gäggeler (University of Bern/Paul Scherrer Institute) and comprises contributions from many experts on the topic from various institutions throughout Switzerland. The white book highlights the imminent loss of experts in the field of radiochemistry and provides solutions to counteract this development.

As of December 10, 2020, the ETH Zurich appointed PSI’s Prof. Dr. Patrick Steinegger as assistant professor of radiochemistry  (tenure track). Thus, the ETH domain took first counter  measures against the imminent loss of radiochemical expertise  in Switzerland, emphasized in the “Weissbuch Radiochemie  Schweiz” by the Swiss Academy of Sciences (SCNAT).  Furthermore, the December issue of CHIMIA (Swiss Chemical  Society) invited to present the diverse radiochemical activities  throughout the country.

PSI researchers have studied the how the electrolyte pH values influence the oxygen evolution reaction (OER) activity and stability of different promising perovskite oxide catalysts for application as anodic electrodes in alkaline water electrolyzers. The OER activity and stability decreased decreasing the electrolyte pH values. By combining electrochemical studies and operando X-ray absorption spectroscopy measurements, it has been suggested that different reaction mechanisms dominate in alkaline and near-neutral electrolyte pH region.