Flow Electrolyzer Mass Spectrometry with a Gas‐Diffusion Electrode Design

Abstract

Operando mass spectrometry is a powerful technique to probe reaction intermediates near the surface of catalyst in electrochemical systems. For electrochemical reactions involving gas reactants, conventional operando mass spectrometry struggles in detecting reaction intermediates because the batch‐type electrochemical reactor can only handle a very limited current density due to the low solubility of gas reactant(s). Herein, we developed a new technique, namely flow electrolyzer mass spectrometry (FEMS), by incorporating a gas‐diffusion electrode design, which enables the detection of reactive volatile or gaseous species at high operating current densities (>100 mA cm−2). We investigated the electrochemical carbon monoxide reduction reaction (eCORR) on polycrystalline copper and elucidated the oxygen incorporation mechanism in the acetaldehyde formation. Combining FEMS and isotopic labelling, we showed that the oxygen in the as‐formed acetaldehyde intermediate originates from the reactant CO, while ethanol and n‐propanol contained mainly solvent oxygen. The observation provides direct experimental evidence of an isotopic scrambling mechanism.

Boosting CO2 electroreduction towards C2+ products via CO* intermediate manipulation on copper-based catalysts

“…Thereby, in situ MS enables the prediction of the reaction pathways. Jiao et al 255 used an innovative electrochemical flow cell for the DEMS system to collect liquid and gaseous products through a porous PTFE membrane, enabling the quantitative analysis of the products, such as CO, CH 4 , C 2 H 4 , C 2 H 5 OH, CH 3 CHO, C 3 H 5 OH, C 3 H 6 O, and C 3 H 7 OH at a large current density (Fig. 24c).…”

Resolving local reaction environment toward an optimized CO2-to-CO conversion performance

“…[28][29][30] Electrochemical mass spectrometry is another powerful tool for real-time detection of volatile species generated at the dependence of either potential sweep 31,32 or electrolyte switching. 33,34 Taking Cu-catalyzed CO 2 RR as an example, Koper's group studied the possible intermediates for C 1 and C 2 pathways 35 and compared their structural sensitivity on probe-inlet online electrochemical mass spectroscopy (OLEMS) apparatus. 36 Later, a flow-cell design was proposed by Clark et al to overcome the mass transport limitation from the probe tip in OLEMS, 37 an even higher detection efficiency was achieved by direct sampling of volatile species from the catalyst coated pervaporation membrane to the mass spectrometer.…”

“…11 More recently, a novel design of electron ionization quadrupole mass spectrometer (EI-QMS) coupled with time-of-flight mass spectrometer (TOF-MS) system has been demonstrated, 38 the former is capable of detecting gaseous products while the latter is very efficient for nebulizing liquid product analysis in real-time. Thereafter, the transient information on the dynamic evolution of liquid products involving aldehydes and alcohols generated at Cu surfaces was clarified, 11,34,39 highlighting the importance of quantitative real-time measurements.…”

Insights into electrochemiluminescence dynamics by synchronizing real-time electrical, luminescence, and mass spectrometric measurements

“…16,17 Thus, the successful marriage of electrochemistry (EC) and MS may offer opportunities for gaining greater insight into electrochemical reactions, including ECL. [18][19][20] Among the endeavors devoted to connecting EC with MS, differential electrochemical mass spectrometry (DEMS) and ECelectrospray ionization mass spectrometry (ESI-MS) are the classic strategies for the detection of gaseous and liquid species, respectively. [20][21][22][23] However, the distance between the electrodeelectrolyte interface (EEI) and the MS inlet brings about a loss of information on eeting intermediates, and the applied high voltage for ionization may cause extra electrochemical changes.…”