| Popis: |
Across many scientific and industrial fields, it is a challenge to analyze chemical reaction products with high sensitivity and fast time-response. This is especially true in systems related to electrochemical energy conversion and storage, such as batteries and fuel cells, where accurate monitoring of fast and transient reaction phenomena often reveals key insights. Here, we present a unique analysis instrument using a microchip-based inlet system to couple a mass spectrometer directly to any liquid test environment, aqueous or non-aqueous, and exhibits a sensitivity up to 2-3 orders of magnitude than conventional differential electrochemical mass spectrometry (DEMS).(1–3) The instrument allows to measure the evolution of volatile products and consumption of reactants at electrode surfaces. Due to its extraordinary sensitivity, the system can measure all the individual volatile molecules desorbing from an electrode surface during a single electrochemical turnover. Product formation can be measured from total Faradaic currents of 1 mA all the way down to 200 nA, corresponding to approximately 0.2% of a monolayer (ML) desorbing from the electrode surface in 1s. These features enable time-resolved, fully quantitative measurements of transient phenomena during electrochemistry, providing fundamental insight in the electrochemical reaction mechanisms. Furthermore, an accurately calibrated on-chip gas system allows rapid gas switching between different gases, both inert and reactive. Due to the near-instantaneous equilibration between gas and electrolyte, the transient response of electrodes to rapid gas exposure changes can be measured. As direct evidence of the ultrahigh sensitivity, i n situ quantification the anodic desorption of less than ~1% of a ML of hydrogen on a Cu electrode in alkaline electrolyte (Fig. 1) is shown.(4) Finally, several examples of quantitative electrochemical measurements will be presented, including lattice oxygen contribution during OER on NiFeOxHy,(2) and hydrocarbon oxidation of propene on palladium. (3, 5) Fig.1 H2 desorption on Cu(pc) in 0.1 M KOH. (4) D. B. Trimarco et al., Electrochim. Acta. 268, 520–530 (2018). C. Roy et al., Nat. Catal. 1, 820–829 (2018). A. Winiwarter et al., Energy Environ. Sci. 12, 1055–1067 (2019). S. B. Scott et al., Catal. Sci. Technol. (2020). A. Winiwarter et al., ChemElectroChem, in press. Figure 1 |
