Toward CO₂ Electroreduction under Controlled Mass Flow Conditions: A Combined Inverted RDE and Gas Chromatography Approach

Abstract

The use of rotating disk electrodes (RDEs) is probably the most convenient way of studying simple electrode reactions under well-defined transport conditions. Standard RDEs become, however, less expedient when the studied electrode process is a complex one, leading to the formation of various reaction products. In these cases, the accurate detection and quantification of the formed products are desirable. If the formed products are gaseous, then the usual way of quantifying them is the use of online gas chromatography (GC), a method that is not compatible with open RDE cells. In order to overcome these difficulties, we present here a sophisticated inverted RDE (iRDE) cell design. The design combines various advantages: it is amenable to the same mathematical treatment as standard (downward-facing) RDEs; it can be operated airtight and coupled to online GC; and due to its upward-facing design, the electrode surface is less prone to blockage by any formed gas bubbles. The iRDE&GC design is tested using simple model reactions and is demonstratively used for studying the electrochemical reduction of CO 2 , accompanied by parasitic hydrogen evolution, on a silver electrode.

Gastight rotating cylinder electrode: Toward decoupling mass transport and intrinsic kinetics in electrocatalysis

“…The cylinder electrode area in the RCE gastight cell is 15 times larger than those common to rotating disk electrodes (RDEs) (disk areas are typically around 0.2 cm 2 ) and because of its geometry, the RCE does not suffer from surface blockage from bubbles evolved in the process which has been a limiting factor for RDE systems. 5 The large geometric area to electrolyte volume in the gas-tight RCE cell results in detection limits for liquid products in the order of few μM in hour-long experiments and the on-line detection of gas products in the order of 1 ppm which are equivalent to partial current densities of less than 10 μA cm À2 . The gastight RCE system presented here offers access to the rigorous study of electrode kinetics even at low current densities in low roughness, idealized electrodes.…”

“…In order to gain insights into fundamental electrocatalytic reaction kinetics and to create a basis for the rational design of electrochemical reactors, we have developed a gastight rotating cylinder electrode (RCE) cell that allows the detection and quantification of gas and liquid products generated on RCEs under the conditions of well‐defined hydrodynamics (Figure 1). The cylinder electrode area in the RCE gastight cell is 15 times larger than those common to rotating disk electrodes (RDEs) (disk areas are typically around 0.2 cm 2 ) and because of its geometry, the RCE does not suffer from surface blockage from bubbles evolved in the process which has been a limiting factor for RDE systems 5 . The large geometric area to electrolyte volume in the gas‐tight RCE cell results in detection limits for liquid products in the order of few μM in hour‐long experiments and the on‐line detection of gas products in the order of 1 ppm which are equivalent to partial current densities of less than 10 μA cm −2 .…”

Efficiency and selectivity of CO2 reduction to CO on gold gas diffusion electrodes in acidic media

“…Because of the high activity of proton reduction at low overpotentials, the current efficiencies found for CO in acidic media are usually low, especially on electrodes with low roughness. In fact, only in a few works in the literature, CO 2 R has been investigated (at small scale) in acidic media 10,11,20,21 . Recent work from Bondue et al 10 has indicated that proton reduction can be fully suppressed in acidic media, as long as the rate of CO/OH − formation from CO 2 R is high enough to compensate the mass transfer of protons to the electrode surface.…”

Mitigating mass transport limitations: hierarchical nanoporous gold flow-through electrodes for electrochemical CO2 reduction

“…Clearly, more work is needed to understand the various effects of mass transport on ECR. Here, a recently developed inverse rotating disk electrode 21 that enables the use of gas chromatography may enable more detailed studies on the effect of mass transport. But regardless of these controversial results with regard of the effect of mass transport on ECR, it is generally accepted that the transport of the reactant CO 2 limits the ECR current density that can be achieved in liquid electrolytes.…”