Studies in heterogeneous catalysis and x-ray spectroscopy of water
Title: Studies in heterogeneous catalysis and x-ray spectroscopy of water
SNIC Project: SNIC 2020/1-22
Project Type: SNIC Large Compute
Principal Investigator: Lars G.M. Pettersson <lgm@fysik.su.se>
Affiliation: Stockholms universitet
Duration: 2020-07-01 – 2021-07-01
Classification: 10304 10407 10302
Homepage: http://xsolasgroup.fysik.su.se/
Keywords:

Abstract

The research of the group is focused on fundamental problems in heterogeneous and electrochemical catalysis and the determination of the structure and origin of the anomalous properties of liquid water. We have developed a new picture of ambient water based on fluctuations between two types of local structures connected to the anomalous properties of water. These become enhanced upon supercooling where thermodynamic response functions seem to diverge at a temperature of 228 K, i.e. below the temperature of homogeneous ice nucleation. These techniques will also be used to investigate structure models from newly developed force-field descriptions of water where we are also actively developing the SCME-GAP force-field model. In a picture of water as locally fluctuating between more compact high-density and more open, tetrahedral conformations the question arises how gases dissolve in the liquid. Does O2 preferentially associate with the low-density regions and will this require special means for fish to extract it from the liquid? We work together with experimental colleagues in Japan on computing XES and RIXS of O2 and water and in fibrous structures modeling the interface between water and gills of fish. In heterogeneous catalysis we exploit new opportunities created by the ultrashort pulses from free-electron x-ray laser sources which enable following chemical reactions in real time. We compute structures, barriers and spectra to assist in the analysis of the experiments which have included CO desorption and oxidation on Ru(0001), as well as hydrogenation of CO on the way to synthetic fuels. We will continue by studying associative desorption of C+O as CO, N2 dissociation and the Haber-Bosch process to make ammonia as well as CO2 reduction both heterogeneously and electrocatalytically. The electrocatalytic CO2 reduction reaction shows high selectivity for ethylene when using specially prepared Cu nanocubes reduced from Cu2O. The origin of this selectivity and enhanced reactivity is still unknown. We have a new SSF funded project focusing on electrochemical generation of hydrogen from waste products, such as glycerol (from biodiesel production) and black liquor (from pulp production). Here our task is to computationally screen for good electrode materials towards both hydrogen production and value-added products that can be used as starting point for further chemical refining. In collaboration with the Swedish nuclear fuel and waste management company (SKB), we conduct studies on the atomic-scale mechanism of copper corrosion which provides insight needed for the design of a safe storage of spent nuclear fuel. This includes the study of the behavior of copper-based minerals in groundwater environments. In addition, we conduct fundamental studies of surface reactivity by a combination of local reactivity descriptors computed by DFT and machine learning algorithms.