TY  - JOUR
A1  - Thürmer, Stephan
A1  - Malerz, Sebastian
A1  - Trinter, Florian
A1  - Hergenhahn, Uwe
A1  - Lee, Chin
A1  - Neumark, Daniel M.
A1  - Meijer, Gerard
A1  - Winter, Bernd
A1  - Wilkinson, Iain
T1  - Accurate vertical ionization energy and work function determinations of liquid water and aqueous solutions
T2  - Chemical science
N2  - The absolute-scale electronic energetics of liquid water and aqueous solutions, both in the bulk and at associated interfaces, are the central determiners of water-based chemistry. However, such information is generally experimentally inaccessible. Here we demonstrate that a refined implementation of the liquid microjet photoelectron spectroscopy (PES) technique can be adopted to address this. Implementing concepts from condensed matter physics, we establish novel all-liquid-phase vacuum and equilibrated solution–metal-electrode Fermi level referencing procedures. This enables the precise and accurate determination of previously elusive water solvent and solute vertical ionization energies, VIEs. Notably, this includes quantification of solute-induced perturbations of water's electronic energetics and VIE definition on an absolute and universal chemical potential scale. Defining and applying these procedures over a broad range of ionization energies, we accurately and respectively determine the VIE and oxidative stability of liquid water as 11.33 ± 0.03 eV and 6.60 ± 0.08 eV with respect to its liquid-vacuum-interface potential and Fermi level. Combining our referencing schemes, we accurately determine the work function of liquid water as 4.73 ± 0.09 eV. Further, applying our novel approach to a pair of exemplary aqueous solutions, we extract absolute VIEs of aqueous iodide anions, reaffirm the robustness of liquid water's electronic structure to high bulk salt concentrations (2 M sodium iodide), and quantify reference-level dependent reductions of water's VIE and a 0.48 ± 0.13 eV contraction of the solution's work function upon partial hydration of a known surfactant (25 mM tetrabutylammonium iodide). Our combined experimental accomplishments mark a major advance in our ability to quantify electronic–structure interactions and chemical reactivity in liquid water, which now explicitly extends to the measurement of absolute-scale bulk and interfacial solution energetics, including those of relevance to aqueous electrochemical processes.
Y1  - 2021
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/63549
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-635495
SN  - 2041-6539
N1  - The data of relevance to this study have been deposited at the following DOI: 10.5281/zenodo.5036382.
N1  - S. T. acknowledges support from the JSPS KAKENHI Grant No. JP18K14178 and JP20K15229. S. M., U. H., and B. W. acknowledge support by the Deutsche Forschungsgemeinschaft (Wi 1327/5-1). F. T., G. M., and B. W. acknowledge support by the MaxWater initiative of the Max-Planck-Gesellschaft. B. W. acknowledges funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and investigation programme (grant agreement No. 883759). D. M. N. and C. L. were supported by the Director, Office of Basic Energy Science, Chemical Sciences Division of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231 and by the Alexander von Humboldt Foundation.
N1  - All publication charges for this article have been paid for by the Royal Society of Chemistry
VL  - 12.2021
IS  - 31
SP  - 10558
EP  - 10582
PB  - RSC
CY  - Cambridge
ER  -