Studies in heterogeneous catalysis and x-ray spectroscopy of water
||Studies in heterogeneous catalysis and x-ray spectroscopy of water|
||SNIC Small Storage|
||Lars G.M. Pettersson <email@example.com>|
||2020-07-01 – 2021-07-01|
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. We perform MD simulations in the supercooled regime to analyze the origin of the enhanced fluctuations. We will apply computed x-ray absorption (XAS) and emission (XES) spectra in conjunction with a fit to the O-O radial distribution function to determine structures that reproduce these data sets. We will then perform an extensive simulation of XES on water based on the determined structures. This will contribute strongly to finally determine the elusive structure of water. 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 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.