Dynamic CO Electrolysis to Methanol on Pt(111) Surfaces Modified with a Pd Monolayer.

In this study, we focus on improving the activity of electrochemical carbon monoxide (CO) reduction toward methanol (CH3OH) on a model catalyst reported previously by our group: a platinum(111) single crystal modified with a palladium monolayer (PdML/Pt-(111)). Dynamic electrolysis with a square potential wave was applied at a negative potential of -0.8 V for CO, while the (more) positive potential was varied between -0.2 V and +0.8 V vs the Reversible Hydrogen Electrode (RHE) for different negative and positive pulse durations. We find a 7-fold increase (compared to static electrolysis) in Faradaic Efficiency (FE) for CO reduction toward methanol (12.6%) when the potential is pulsed between -0.8 and +0.4 V, with 1-s pulses, and an 11-fold increase when the potassium cation concentration in the electrolyte was raised to 1 M (20.1%). Additionally, a 5-fold improvement in the FECH3OH was found during dynamic carbon dioxide (CO2) electrolysis as well, when the potential is pulsed between -0.9 and +0.4 V. The surface of PdML/Pt-(111) was investigated postcatalysis using cyclic voltammetry (CV), Scanning Electron Microscopy (SEM), and Atomic Force Microscopy (AFM). The formation of bilayer islands and the exposure of the Pt single-crystal surface were found using all three techniques. We find that applying dynamic electrolysis conditions significantly enhances methanol production under all probed conditions. This finding could be extended to other electrocatalysts facilitating methanol formation from CO(2) for improved performance and minimization of the Hydrogen Evolution Reaction.