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A multivariate calibration method for mass spectrometry is presented that enables a quantitative analysis of gas mixtures containing interfering gases that contribute to the same mass-to-charge ratios at nominal resolution. Multiple calibration gas mixtures with linearly independent compositions are used in order to obtain the calibration constants for the contribution of each gas to each of the mass-to-charge ratio peaks. The method was successfully applied to the quantitative detection of CO in a mixture with CO2 and N2, which represents a difficulty commonly encountered in heterogeneous catalysis and electrocatalysis research. [ABSTRACT FROM AUTHOR]

Molecular dynamics (MD) simulations at a constant electric potential are an essential tool to study electrochemical processes, providing microscopic information on the structural, thermodynamic, and dynamical properties. Despite the numerous advances in the simulation of electrodes, they fail to accurately represent the electronic structure of materials such as graphite. In this work, a simple parameterization method that allows to tune the metallicity of the electrode based on a quantum chemistry calculation of the density of states (DOS) is introduced. As a first illustration, the interface between graphite electrodes and two different liquid electrolytes, an aqueous solution of NaCl and a pure ionic liquid, at different applied potentials are studied. It is shown that the simulations reproduce qualitatively the experimentally-measured capacitance; in particular, they yield a minimum of capacitance at the point of zero charge (PZC), which is due to the quantum capacitance (QC) contribution. An analysis of the structure of the adsorbed liquids allows to understand why the ionic liquid displays a lower capacitance despite its large ionic concentration. In addition to its relevance for the important class of carbonaceous electrodes, this method can be applied to any electrode materials (e.g. 2D materials, conducting polymers, etc), thus enabling molecular simulation studies of complex electrochemical devices in the future., (© 2024 The Author(s). Advanced Materials published by Wiley‐VCH GmbH.)

Carefully assessing the energetics along the pathway of the oxygen evolution reaction (OER), our computational study reveals that the "classical" OER mechanism on the (110) surface of iridium dioxide (IrO 2 ) must be reconsidered. We find that the OER follows a bi-nuclear mechanism with adjacent top surface oxygen atoms as fixed adsorption sites, whereas the iridium atoms underneath play an indirect role and maintain their saturated 6-fold oxygen coordination at all stages of the reaction. The oxygen molecule is formed, via an Ir-OOOO-Ir transition state, by association of the outer oxygen atoms of two adjacent Ir-OO surface entities, leaving two intact Ir-O entities at the surface behind. This is drastically different from the commonly considered mono-nuclear mechanism where the O 2 molecule evolves by splitting of the Ir-O bond in an Ir-OO entity. We regard the rather weak reducibility of crystalline IrO 2 as the reason for favoring the novel pathway, which allows the Ir-O bonds to remain stable and explains the outstanding stability of IrO 2 under OER conditions. The establishment of surface oxygen atoms as fixed electrocatalytically active sites on a transition-metal oxide represents a paradigm shift for the understanding of water oxidation electrocatalysis, and it reconciles the theoretical understanding of the OER mechanism on iridium oxide with recently reported experimental results from operando X-ray spectroscopy. The novel mechanism provides an efficient OER pathway on a weakly reducible oxide, defining a new strategy towards the design of advanced OER catalysts with combined activity and stability., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

A multivariate calibration method for mass spectrometry is presented that enables a quantitative analysis of gas mixtures containing interfering gases that contribute to the same mass-to-charge ratios at nominal resolution. Multiple calibration gas mixtures with linearly independent compositions are used in order to obtain the calibration constants for the contribution of each gas to each of the mass-to-charge ratio peaks. The method was successfully applied to the quantitative detection of CO in a mixture with CO 2 and N 2 , which represents a difficulty commonly encountered in heterogeneous catalysis and electrocatalysis research., (© 2018 John Wiley & Sons, Ltd.)