Pulsed electrolysis is widely explored as a dynamic operation strategy to enhance current efficiency, energy efficiency, and stability in electrochemical CO 2 reduction. Yet, its benefits for systems employing gas diffusion electrodes (GDEs) remain insufficiently understood. Here, we develop a time-dependent microkinetic-continuum model for CO 2 reduction on silver GDEs that resolves coupled mass-transport, concentration profiles, and surface coverages. A literature-based microkinetic scheme with parallel pathways to CO, H 2 , and HCOOH is embedded into a one-dimensional continuum GDE model that accounts for different electrolyte distributions within the catalyst layer. Using this framework, we assess the influence of pulse duration and catalyst-layer wetting state on partial current densities and current efficiency. Pulsed operation induces pronounced transient spikes in CO partial currents after potential switching. However, at equal average total current density, the time-averaged CO current efficiency remains below that of steady operation, as the off-time outweighs transient CO 2 replenishment, relaxation of ion concentrations, and surface coverages. Catalyst-layer wetting and electrolyte distribution exert a stronger influence on overall CO 2 utilization than pulsed operation, which primarily shifts the apparent polarization behavior and redistributes current among CO, H 2 , and HCOOH under transport-limited conditions without improving intrinsic CO 2 utilization in Ag-based GDE systems. These findings highlight that dynamic operation in GDEs should be evaluated in terms of overall CO 2 utilization at equal average total current density rather than through isolated selectivity gains.
Plischka et al. (Tue,) studied this question.
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