Enabling real-time detection of electrochemical desorption phenomena with sub-monolayer sensitivity

Abstract Electrochemical reactions play an increasingly important role in sustainable energy conversion and chemical synthesis. Better understanding of catalytic mechanisms at electrode surfaces is thus important for the transition to a clean-energy economy, but is hindered by the difficulty of real-time detection of reaction products and intermediates during electrochemistry experiments. Herein, we present a new type of electrochemistry – mass spectrometry (EC-MS) based on a versatile gas inlet to vacuum fabricated onto a silicon microchip, and compare it to established techniques with focus on sensitivity, time response, and mass transport. The inlet system is able to capture reactant molecules directly from an electrode surface and pass them on to a mass spectrometer on a sub-second time scale with 100% collection efficiency for quantitative analysis with unprecedented sensitivity. The high sensitivity and fast time-response, coupled with well-characterized mass transport of both reactants and products in this setup enables sub-turnover resolution for analysis of electrochemical reactions. The technology and concepts presented here can serve as a platform to improve in-situ mass spectrometry in electrochemistry as well as other fields.